    Subject: rec.audio FAQ (part 1 of 4)

Archive-name: AudioFAQ/part1
Last-modified: 1993/3/2
Version: 1.2

1.0 Contents:

    Part 1:
	1.0	Contents
	2.0	Organization
	3.0	Purpose
	4.0	Omissions
	5.0	Credits
	6.0	Errors and Corrections
	7.0	Disclaimer
	8.0	Copyright Notice
	9.0	Speakers
	10.0	Amplifiers
    Part 2:
	10.10	Amplifiers (continued)
	11.0	CD Players, CDs, Turntables, and LPs
	12.0	High Fidelity Systems
    Part 3:
	12.4	High Fidelity Systems (continued)
	13.0	Listening Rooms and Houses
	14.0	Recording
	15.0	Mail Order
	16.0	Wire
    Part 4:
	16.4	Wire (continued)
	17.0	The Press
	18.0	Retail
	19.0	Miscellaneous
	20.0	Net Protocol

2.0 Organization:

This FAQ is divided into a preamble and a list of subjects.  Each
subject is described by a list of questions and answers.  Some
questions have no answers yet.  That's life.

This FAQ is split into four individual postings.  This FAQ also
references a frequent posting of sources for audio via Mail Order.
That list is maintained by nau@SSESCO.com (William R. Nau).  Contact
Mr. Nau directly for information or corrections to that posting.
The list is also available via FTP in the pub/rec.audio directory
of SSESCO.com.

Lines beginning with "|" are new since the last version of the FAQ.

3.0 Purpose:

The purpose of this FAQ is to address frequently-asked questions as
a whole, so that rec.audio volume can be reduced.  Towards this end,
we assembled a list of common questions, and some general answers to
these questions.  Audio is part science and part art, so some of the
answers are objectively correct, while others try to open-mindedly
present both sides of a subject.

4.0 Omissions:

Many valuable things have been left out of the FAQ.  In part this is
because there is just too much to say about audio.  In part, this is
because the general reader doesn't need that much detail.  Also, some
things were omitted because they are too controversial or inflammatory.

5.0 Credits:

This FAQ is the work of many people.  Allow me to thank everyone who
helped now.  We appreciate all of your contributions.  However, all
blame and criticism should go to Bob Neidorff at neidorff@uicc.com.
Some of the contributors to this FAQ are listed below.  Others have
made great contributions, but are no less appreciated.

	andrew@research.att.com (Andrew Hume)
	jj@research.att.com (jj)
	neidorff@uicc.com (Bob Neidorff)
	Rick Oakley (no internet access)
	DPierce@world.std.com (Richard d Pierce)
	P.Smee@bristol.ac.uk (Paul Smee)
	gmw1@cunixa.cc.columbia.edu (Gabe M. Wiener)

6.0 Errors and Corrections:

Some errors are intentionally included in this FAQ.  (It's easier to say
that and later admit we were wrong, than to claim that this is a best
effort).  If you have a correction to the FAQ, additional information,
or a new topic for the FAQ, please send e-mail to neidorff@uicc.com
describing your thoughts in detail.  Please include your e-mail address
in your submission, so that we can stay in touch.  Every submission will
be considered for inclusion in the next release of the FAQ.  This FAQ
will be reposted every two months.

7.0 Disclaimer:

Everyone's human.  Nothing is perfect.  The people who wrote the
information here put varying amounts of research into their work.
To the best of my knowledge, no one made any contribution or
comment because of a vested interest.

Audio is a very lucrative and competitive industry, filled with
honest companies, aggressive marketing people, people who stretch the
truth very thin, excellent products, and lousy products.  We tried
hard to screen the hype from valuable data.  If we insulted, omitted,
or otherwise disturbed you, your company, your product, or something
you feel strongly about, please let me know.

The information here attempts to paraphrase a large portion of the
information exchanged on rec.audio.  At times, people will make
recommendations or suggestions to others on rec.audio.  Some of these
statements are included here because we have been asked to include
statements of that sort.  These statements, and everything in this
document is the opinions of various people.  Nothing here is intended
as recommendation or suggestion.

Further, no matter how it is worded, nothing here should be taken as
fact.  The authors take no responsibility for any use of this
information.

8.0 Copyright Notice:

The information contained here is collectively copyrighted by the
authors.  The right to reproduce this is hereby given, provided it is
copied intact, with the text of sections 1 through 8, inclusive.
However, the authors explicitly prohibit selling this document, any
of its parts, or any document which contains parts of this document.

9.0 Speakers:

9.1 What should I listen to when evaluating speakers?
	The most important thing is to listen to recordings that
	you *know*.  Any good salesman will play you recordings
	that highlight that particular speaker.  Do not be embarrassed
	about bringing a stack of CD's with you to the hi-fi shop.

	Do not spend your valuable listening time switching between a
	dozen pairs every 3 seconds.  If you are shopping at a quality
	store, the dealer will, from the description of your room, your
	size requirements, your musical tastes, and your budget, be able
	to show you a couple of pairs that will be close to what you
	want.  Spend several minutes listening to each.  When you think
	you're close, don't be embarrassed about spending half an hour
	or more listening to the speakers.  You're going to have them in
	your home for a lot longer, and many speakers will cause
	"listening fatigue" after a short time.  Make sure you really
	like them before you hand over money.

	One thing to try is well recorded "Spoken Word" records; most
	people have a very good ability to tell when a speaking voice
	sounds unnatural, even if they've never heard the person
	speaking live.  If you play an acoustic instrument, find
	something that features that instrument solo, or in a small
	group; make sure it really sounds like it should.  Almost
	everyone has heard a live piano.  Piano can be very revealing.

	Blues, jazz, folk, or 'easy listening' music with simple
	instruments and a female vocalist is also revealing.  Well done
	female singing voices provide a very good test of a system's
	response.  Try something simple and soft, which will let you
	hear any noises coming from the system; and something complex,
	with lots of instruments all happening at once, to make sure the
	system doesn't go muddy when things get complicated.  And, of
	course, try a few of your favorites, and see if you like what
	happens with them.

	If a sales person suggests some music to listen to, the odds are
	that it isn't the most revealing.  Sales people tend to suggest
	things which sound great.  Anything you own and like is good,
	because you know it and are happy to listen to it carefully.  No
	matter how good the recording, if you don't like Opera, you
	won't listen to it as carefully as your favorite, scratchy,
	1940's rhythm and blues.

	Most important is to listen to something you are familiar with.
	Even if a recording is flawed (and what ones aren't?), how is it
	different from your normal setup?  Some of the most important
	differences are "Gee, I never heard that instrument before!"

9.2 What should I listen for when evaluating speakers?
	When comparing two speakers side-by-side, doing an AB
	comparison, be extremely careful to match the levels before
	evaluating.  A slight level difference can make one speaker
	sound better, even though the difference may not be perceived
	as a level difference.  Some claim that you will be influenced
	by a difference of less than 1/2 dB!

	First and foremost, the sound should be natural.  If you listen
	to vocals, close your eyes and try to picture someone singing in
	the same room with you.  Does it sound realistic?  Likewise with
	instruments.  You selected recordings of instruments that you
	like and have heard live.  Do they sound like what you remember

	them sounding like live?

	Your very first impression should be something like "what nice
	sound".  If your initial gut reaction is "gosh, what a lot of
	detail", the system is likely to be heavy in the treble (often
	interpreted by beginners as "more detailed") and you'll probably
	find that annoying after a while.  If your first reaction is
	"hey, what powerful bass", then the system is probably
	bass-heavy, rather than ideal.  The most common mistake for
	beginners is to buy a system with REALLY powerful bass, because
	it sounds "impressive" at first.  After a while, though, you'll
	get tired of being thumped on the head by your music.

	Not to say that good bass and treble aren't important.  But your
	first realization should be that the music is all there, and
	that it comes together as good music, without one particular
	part trying to dominate it.  Sit back and listen to it for a
	bit.  You should be able to pick out the individual instruments
	if you want.  They shouldn't force themselves on you, and you
	should also be able to hear the music as a single piece, the sum
	of its parts, without feeling like each of the instruments is
	trying to grab your attention away from the others.

	You should check how things sound with the amp turned up, and
	also with it turned down to a fairly low volume level.  Some
	speakers which sound very nice at low levels begin to sound
	confused, like they can't cope, when turned up.  On the other
	hand, some sound nice loud, but sound thin and bodiless when you
	turn them down a bit.  With the spoken word or female vocalist,
	listen for "sibilance", a pronounced 'hiss' at the end of 's'
	and 'z' sounds.  It shouldn't be there.  Most planar speakers
	just can't play very loud.  Whatever you hear, do some
	auditioning at the maximum volume you anticpate ever wanting.

	It is acceptable and sometimes desirable to switch the stereo to
	mono to evaluate naturalness.  Mono is a good test of both the
	room and the speakers.  The image should be rock-solid dead
	center, and not move with signal or level.  If it isn't perfect
	mono, it will be nearly impossible to create a good stereo.

	A speaker in a large box is capable of producing low frequencies
	at higher volumes with more efficiency than a small box, but
	that doesn't mean that a small box can't have great bass, it
	just won't be as efficient and can't play as loud.

	Good speakers can "recreate a natural stereo sound stage",
	placing some instruments to the left of the left speaker, some
	sounds in the middle, and some to the right of the right
	speaker.  Poorer speakers make it harder to localize voices.

9.3 Why use a subwoofer?  Will it help?  One or two?
	One reason to get a subwoofer is to add bass to a feeble system.
	A second reason is to move the lowest frequencies to a separate
	driver, and thereby reduce a particular kind of distortion
	caused by the nonlinear mixing of different sounds, called
	"intermodulation distortion". A third is to increase the power
	handling ability of the system and the overall reliability.  All
	are valid reasons, but it isn't so simple.

	To improve the sound of a good speaker system, a subwoofer must
	"integrate smoothly" into the system, extending the bass without
	causing peaks or dips.  Many subwoofers have a crossover that
	goes between your amp and your main speaker which sends the lows
	to the subwoofer and sends the higher frequency signals to the
	main speakers.  This may damage the perfect sound of a good
	system, it may sound similar, or it may sound better.

	Most good small speaker systems have a bass peak at resonance,
	which attempts to compensate for the absence of lower bass.
	Like it or not, this is the only way to make a small system
	sound realistic. If the small system is done well, the
	improvement you will get from a subwoofer will be small, but
	still real and, to many, significant.

	Correctly done, a good subwoofer will enhance the sound of a
	good small-box system.  Done wrong or haphazardly, anything is
	possible.  Even a fine large speaker system might benefit from
	careful addition of a subwoofer.  However, the better the
	original system, the more likely it will be that a modest
	subwoofer will do more harm than good.

	Low frequencies travel less directionally than high frequencies,
	so many people say that only one subwoofer is required for good
	sound.  This is true to some extent, but not completely true.

	There are a few reasons for getting two subwoofers.  Some feel
	that you need two subwoofers to accurately reproduce the stereo
	image, no matter how little low-frequency stereo information
	there is.  Others feel that two subwoofers are much easier to
	set up in a room, less likely to excite standing waves in the
	room, and give smoother sound.

	A third reason is that two subwoofers can produce twice the
	sound of one.  Finally, even though subwoofers produce very low
	frequency sound and very low frequency sound is non-directional,
	subwoofers also have output at 100 Hz, and sound at 100 Hz is
	directional, so two subwoofers will give a slightly better
	stereo image than one.  Assuming, of course, that the two are
	separated by at least two feet.

	Finally, even though original source signals rarely contain any
	music with stereo components below 50Hz, there may be some noise
	component with low-frequency out-of-phase noise.  This unusual
	noise might add a sense of space to a recording if it is
	reproduced by a system in which the woofers are very far apart.

	It is still true that a single good subwoofer, correctly added
	to a system will help the sound but two will probably help more.

9.4 How do you connect a subwoofer to a stereo?
	Many subwoofers contain their own amplifier and crossover.
	For these, take the preamp output and feed it into the subwoofer
	amp input and also into the main amplifier.

	For other subwoofers, just run them in parallel with your main
	speakers, or combine them into your system with your own bass
	amplifier and crossover.

	Some A/V receivers contain a splitter specifically for use with
	subwoofers.  If you have one of these, you will either want a
	separate amplifier for your subwoofer or an amplified subwoofer.

	Consult the manual which comes with the subwoofer.

9.5 What do I need for surround sound?
	"Surround Sound" has referred to a number of different products
	over the years.  Many mass-fi receivers have "Surround Sound"
	buttons that do little more than muck up the imaging.

	In recent years the term "Surround Sound" has become synonymous
	with the surround systems produced by Dolby Laboratories.  Dolby
	Surround comes in several flavors, such as passive surround
	(which simply decodes the phase information and sends it to the
	rear speakers) and the more advanced system called Pro Logic.
	Pro Logic system uses computer circuitry to route directional
	information to the appropriate speakers.

	Generally, one needs at least two more speakers beyone the main
	stereo pair.  Advanced Pro Logic systems such as the Lexicon and
	Fosgate can accommodate several more speakers beyond the two
	additional ones (usually placed in the rear).  Often one can
	find Pro Logic systems with two front, two rear, two side, as
	well as a center channel speaker for dialogue.

9.6 I was just approached (accosted?) by a couple of kids driving a van
	that said they had some GREAT speakers to sell. They are
	overstocks, used by major recording studios and DJ's or even
	hot, and they normally sell for $1000/pr, but they'll let me
	have them for just $399. Am I getting ripped off?

	Yes, you most certainly are. The speakers these people sell are
	none of what they describe. They are never used in studios.
	There might be one or two DJ's out there that use them because
	they can't afford anything else.  They are not overstocks, and
	in all likelyhood, they are NOT HOT!.

	Are they good speakers? No, they're, at best, no better than the
	big boom boxes you find in $400 rack systems in department
	stores.  They are worth no more than what the kids paid for them
	($100/pr).

	The speakers go under names like "Acoustic Monitor DB IV",
	"Acoustic Linear," "Pro-Poly," "Audio Reference 4350" and so on.
	They all "feature" things like "liquid cooled 3" tweeter",
	poly-cone 12" woofer, fantastic (but impossible) frequency
	response, 98 db/watt sensitivity, and so on.

	These speaker are made by a couple of manufacturers with the
	intent of being sold exactly this way.  They cost the kids in
	the van about $100 a pair, and the kids are given minimal
	training about what kinds of stories to use, what parking lots
	are the most likely to generate sales (department store parking
	lots near colleges in September is a great time for these guys).
	Anything over and above the $100 dollars the kids paid is pure
	profit (except for gas money).

	Stay away, you're getting ripped off.

9.7 What speakers should I consider in the $XXX/pair price range?
	This is probably the most commonly asked question on rec.audio,
	and also the most impossible to answer.  The market keeps
	changing, everyone has different tastes, and no one has the time
	to listen to even 10% of the products available in any country.
	Also, many good products are only available in specific regions
	or countries.

	If you really want recommendations and are willing to listen to
	the opinions of others, check the past few issues of Stereophile
	Mag.  Although they are strongly biased towards very expensive
	gear and have their own particular other biases, they do steer

	you to some very good equipment in their frequently-updated list
	of "RECOMMENDED COMPONENTS".

9.8 Can you build better speakers than you can buy?
	Some people can build better than you can buy.  These people are
	either experts, golden ears, extremely well equipped, inspired,
	or a combination of the above.

	Some companies have plans available to entice you into buying
	their drivers: Audio Concepts, Audax, Dynaudio, Focal, KEF, and
	Scanspeak.  Your success rate with these plans will probably be
	very good IF your cabinetry skills are very good and IF you
	follow the plans precisely.  If you deviate (as everyone does),
	anything is possible.

	Stereophile has published three different plans designed by Dick
	Olsher which are similar two-way ported systems. A recent one of
	these was in Stereophile Nov '90, pages 94-127. Audio Magazine
	published a plan called "The Pitts" by Ken Kantor, in Audio, Nov
	'88 pages 65-71 continued in Dec '88 pages 73-77.  This plan is
	a two-way sealed box.

	I have built one published design and one manufacturer's design.
	I believe that both met my expectations.  They took me a long
	time to build, taught me a lot, were fun projects, and sounded
	good when finished.

	I also believe that a commercial system which cost what my parts
	cost will never sound anywhere near as good as the one I build.
	If you consider $2/hour for my time, however, building is
	financial suicide.

	Designing your own system is even more a can-of-worms, and
	should be left to those with either a strong stomach, a very
	forgiving ear, infinite resources, or excellent guidance.

9.9 Where can I read more about speaker building?
	Speaker Builder Magazine
		Audio Amateur Publications
		PO Box 494
		Peterborough NH  03458 USA
		603-924-9464
	The Loudspeaker Design Cookbook, Fourth Edition
		by Vance Dickason (C) 1991
		ISBN 0-9624191-7-6
		$29.95 + $2.00 S&H from
		Old Colony Sound Lab
		PO Box 243
		Peterborough NH  03458-0243 USA
		603-924-9464
	High Performance Loudspeakers by Martin Colloms
	Synergetic Audio Concepts Classes and Newsletters
		Syn-Aud-Con teaches classes on Audio and Acoustics
		12370 W. Co. Rd. 100 N.
		Norman IN  47264 USA
		812-995-8212
9.10 Where can I buy speaker drivers?
	A & S Speakers (Broad line)
		3170 23rd Street
		San Francisco CA  94110 USA
		415-641-4573
	Audio Concepts (Their own kits plus drivers)
		901 South 4th Street	
		LaCrosse WI  54602 USA
		800-346-9183
	Phil Baker (Surplus cabinets only)
		546 Boston Avenue
		Medford MA  02155
	Carbonneau
		609 Myrtle NW
		Grand Rapids MI  49504 USA
		616-456-9528
	Drexler Audio Systems (Bandor Speaker Distributor)
		14 Rose Lane
		Rosemont PA  19010
	Gold Sound (Broad line including pro speakers)
		PO Box 141
		Englewood CO  80151 USA
		303-789-5310
	Madisound (Broad line)
		8608 University Green
		Box 4283
		Madison WI  53711 USA
		608-831-3433
	McGee Electronics (Polydax, Pyle, Motorola, EV, MTX)
		1901 McGee Street
		Kansas City MO  64108-1891 USA
		913-491-5287 or 800-876-2433
	Meniscus
		2442 28th Street SW Ste D
		Wyoming MI  49509 USA
		616-534-9121
	Parts Express
		340 East First Street
		Dayton OH  45402-1257 USA
		513-222-0173
	Solen Electronique (Airborne, Audax, Ceratech, Dynaudio, Eton,
		Lpg, Morel, Peerless, Scan-Speak, Seas, Solen, Vifa)
		4470 Avenue Thibault
		St.-Hubert, QC  J3Y 7T9 Canada
		Voice 514-656-2759
		FAX 514 443-4949
	Speakers Etc.
		1828 West Peoria Avenue
		Phoneix AZ  85029 USA
		602-944-1878
	SRS Enterprises (Pyle, Pioneer)
		318 South Wahsatch Avenue
		Colorado Springs CO  80903 USA
		719-475-2545
	Transducer Technology (Cabasse, Accuton, Vieta,
			Audiom by Focal, Stage, Tekton)
		4320 Spring Valley Road
		Dallas TX  75244
		214-991-6994
	Zalytron (Broad line including kits)
		469 Jericho Turnpike
		Mineola NY  11501 USA
		516-747-3515

9.11 Where can I buy loudspeaker kits?
	Audio Concepts, Inc. (Wide range of kits.  Catalog available)
		901 South Fourth Street
		La Crosse WI  54601 USA
		608-784-4570
	Fried Products (Parts kits starting $550.  Catalog available)
		(Emphasizes high-end transmission line speakers)
		(Parts kits have plan, crossover, and driver)
		Conshocken Road
		Conshocken PA  19428 USA
		215-277-9004
	Mahogany Sound (Parts kits and Woodstyle kits)
		(Parts kits have plan, crossover, and driver)
		(Woodstyle kits also have 3/4" MDF veneered boxes)
		(Prices $150/pair to $500/pair.  Catalog available)
		(Two way, three way & subwoofer kits)
		2610 Schillingers Rd #488
		Mobile AL  36695 USA
		205-633-2054
	Also see above, under suppliers for speaker drivers.

9.12 How can I improve the sound of my speakers?
	The best way to change the sound of your speakers is to change
	where you put them.  Ideally, the speakers should be located at
	ear level, in front of you, squared off between you.  It's then
	a matter of fiddling with a) the angles, b) the distance apart,
	c) the distance from you, and d) the distance from the wall.
	Just moving the speakers around in the room or putting them onto
	stands can make a major difference. For more on speaker
	placement, see 13.1 below.

	Other than that, speaker modifications can be a can of worms, or
	can produce very subtle changes, which you might prefer.  For
	example, you might improve a speaker by adding some cross braces
	of 1"x1" wood from left to right and from front to back.  This
	will stiffen the cabinet and reduce speaker cabinet wall
	vibrations, which probably hurt sound quality.  Alas, this will
	be most effective with lower-cost and poorly built speakers.

	Along similar lines, some claim success putting lead wire or
	epoxy putty on thin parts of the speaker to damp out resonances.
	You can try doing this to the thinner parts of the speaker
	"basket" or frame, or to the front "baffle" or supporting panel.

	Still another "tweak" is to add sound deadening felt pads to the
	inside walls of the speaker.  Instead of felt pads some advocate
	sand-filled latex coatings on the inside walls of speakers.
	Others advocate ceramic tiles held in place with "thinset".
	Still others rave about commercial products like AC Glop,
	Acoustic Magic, and Bostik Sheet.  However, the people who rave
	about these products tend to be the same people who sell them.

	Any change along the lines of adding felt, cross-bracing, or
	putty will have subtle effects on the sound.

	For the brave at heart, you can replace old or cheap drivers
	with better ones, but the results of this one change can be very
	dissatisfying if you happen to get the wrong type of driver for
	that application, and may never sound right, even if you use a
	similar driver. Speaker system design is still somewhat of a
	science and somewhat of an art.  Throwing paint on a canvas
	often makes a mess.

	Whatever change you try, don't "burn your bridge" home.  Be sure
	that you can undo whatever change you did, just in case.  Many
	tweaks to good speakers, no matter how well thought through,
	will correct for one flaw, but create others, or correct a flaw
	that the designer had cleverly used to his advantage.

9.13 How can I replace/re-cone my old speakers?

	The best chance of success is to buy an identical replacement
	speaker driver from the manufacturer of the system.

	Second choice is to buy the exact same driver from a
	distributor.  This is sometimes difficult because it is hard to
	learn exactly what driver the manufacturer used.  In addition,
	EVEN IF the manufacturer used stock speakers, they might have
	used matched pairs or selected speakers by hand for an exact set
	of specific characteristics.

	There are companies that rebuild drivers, but they charge quite
	a bit.  I have heard $75 per driver. This is rarely done for
	anything but very expensive commercial drivers.  Speaker
	manufacturers will often sell owners the materials that they
	need to repair a speaker.  If you are handy with delicate
	things, it is worth a try.

	In addition to speaker manufacturers, there are companies which
	sells rebuild kits for approximately $30 per pair, containing
	new foam, a special glue, and instructions.  If you have a blown
	or distorted voice coil, this still won't help. A few netters
	have used rebuild kits from this company successfully. Contact:
		Stepp Audio Technologies
		PO Box 1088
		Flat Rock NC  38731 USA
		800-747-3692

|	Another vendor of speaker repair parts is:
		Simply Speakers
		P. O. Box 22673
		St. Petersburg FL  33742 USA
		800-767-4041 or 813-571-1245

	Some speaker manufacturers have very good warranties.
	Electro-Voice warranties all professional products for life.
	KEF has a similarly broad warranty on their speakers.  Contact
	the manufacturer first.

9.14 What computer programs can I use to design speakers?
	There are many useful programs available, but none are complete
	without a good knowledge of speaker design. Further, you will
	NEED to supplement any program with hand tweaking for the best
	sound.  Finally, no simulation program is ever useful without
	good model parameters, and the parameters which manufacturers
	give you are often imperfect, so many good designers strongly
	recommend your own lab measurements.  The Loudspeaker Design
	Cookbook (see 9.9) tells you how to measure a speaker, and also
	enough theory to feel confident with a good program.

	You can get a lot done with a simple spreadsheet and the
	equations in a book like The Loudspeaker Design Cookbook.

	Active Filter Designer by Fernando Garcia Ciesca
		$17.50.  Crossover design.
	BoxModel by Robert Bullock
		$50.00.  Sealed, vented, and passive radiator
		modeling below 400Hz.
	CACD by Scientific Design Software
		Crossover optimizer.
	CALSOD by Witold Waldman
		$65 basic model, $300 complete.
		Crossover optimizer.
	Crossover Design by G. R. Koonce
	Driver Eval by G. R. Koonce
		$25 for both.  Simple programs do what they say.
	Filter Designer 1 by SpeakEasy
		$195 Crossover design program
	Loudspeaker by Maximum Effort Software
		$65 Box design for many different enclosures
		plus crossover network design
	LEAP by Audio Teknology
		$295 to $895 depending on options.
		Complete multi-way design program.
	Low Frequency Designer by SpeakEasy
		$195 Design many different box types.
	LMP by Ralph Gonzales/Sitting Duck Software
		$49.50 Crossover characteristic display
	MacSpeakerz by True Image
		$249 Apple Macintosh box and crossover design
	ModelONE by TDR
		$288 Does auto sound design knowing the
		patterns of various car interiors
	Perfect Box (Shareware, $40 registration in US funds)
		Warren A. Merkel; 2851 Newcomb Ct; Orlando, FL 32826
		MS-DOS executable.  Simulation of low-frequency
		speaker performance (10Hz-200Hz).
		available by ftp from: wuarchive.wust1.edu
		directory /usenet/comp.binaries.ibm.pc/volume12/perf
	PXO by Robert Bullock
		$50 simple crossover design program
	Speak by DLC Designs
		$395 Does box design and crossover design
	Speaker Designer by Stuart Bonney
		$19.50 Low-frequency box design.
	Two-Way Active Crossover Design by Gary Galo
		$20 Simple crossover component calculation
	XOPT by Peter Schuck
		$199 Complete filter design; rumored to have bugs

9.15 Can I magnetically shield my speakers for use near a TV?
	You probably will need to buy speakers that are made with an
	integral magnetic shield.  Magnetic shielding is usually done
	by either shielding the speaker magnet or by cancellation of the
	magnetic field very close to the magnet, or by both.  Shielded
	speakers are NOT built by lining the enclosure with metal.
	While it sounds like a good idea, it doesn't work.

	A common magnet shield is a mild steel cup around the magnet.
	This is the cheapest shield, and is usually fairly ineffective.
	It also will interfere with the speaker's critical magnet gap,
	so this type of shield can hurt speaker performance by shorting
	the magnetic field and reducing the magnetic flux density in the
	gap, which can reduce efficiency and affect the speaker's low
	frequency performance.

	Cancellation is done using a reverse-polarized magnet glued to
	the back of the main magnet.  If done right, it can almost
	completely cancel the rear stray field.  In some cases it can
	also increase the magnetic flux density in the gap, which may
	or may not be desirable.

9.16 What are all of these abbreviations people use for speakers?
	Most of these parameters are well documented in the Loudspeaker
	Design Cookbook. (see 9.9)  In summary:

	Fs    Driver free air resonance, in Hz.  This is the point at
		which driver impedance is maximum.
	Fc    System resonance (usually for sealed box systems), in Hz
	Fb    Enclosure resonance (usually for reflex systems), in Hz
	F3    -3 dB cutoff frequency, in Hz
	
	Vas   "Equivalent volume of compliance", this is a volume of
		air whose compliance is the same as a driver's
		acoustical compliance Cms (q.v.), in cubic meters
	
	D     Effective diameter of driver, in meters
	Sd    Effective piston radiating area of driver in square meters
	Xmax  Maximum peak linear excursion of driver, in meters
	Vd    Maximum linear volume of displacement of the driver
		(product of Sd times Xmax), in cubic meters.
	
	Re    Driver DC resistance (voice coil, mainly), in ohms
	Rg    Amplifier source resistance (includes leads, crossover,
		etc.), in ohms
	
	Qms   The driver's Q at resonance (Fs), due to mechanical
		losses; dimensionless
	Qes   The driver's Q at resonance (Fs), due to electrical
		losses; dimensionless
	Qts   The driver's Q at resonance (Fs), due to all losses;
		 dimensionless
	Qmc   The system's Q at resonance (Fc), due to mechanical
		losses; dimensionless
	Qec   The system's Q at resonance (Fc), due to electrical
		losses; dimensionless
	Qtc   The system's Q at resonance (Fc), due to all losses;
		dimensionless
	
	n0    The reference efficiency of the system (eta sub 0)
		dimensionless, usually expressed as %
	
	Cms   The driver's mechanical compliance (reciprocal of
		stiffness), in m/N
	Mms   The driver's effective mechanical mass (including air
		load), in kg
	Rms   The driver's mechanical losses, in kg/s
	
	Cas   Acoustical equivalent of Cms
	Mas   Acoustical equivalent of Mms
	Ras   Acoustical equivalent of Rms
	
	Cmes  The electrical capacitive equivalent of Mms, in farads
	Lces  The electrical inductive equivalent of Cms, in henries
	Res   The electrical resistave equivalent of Rms, in ohms
	
	B     Magnetic flux density in gap, in Tesla
	l     length of wire immersed in magnetic field, in meters
	Bl    Electro-magnetic force factor, can be expressed in
		Tesla-meters or, preferably, in meters/Newton
	
	Pa    Acoustical power
	Pe    Electrical power
	
	c     propogation velocity of sound at STP, approx. 342 m/s
	p     (rho) density of air at STP 1.18 kg/m^3

10.0 Amplifiers
	Note: A receiver contains an amplifier, so the following
|	questions apply to both receivers and amplifiers.  In the
|	following text, "amp" and "amplifier" are used synonymously.


10.1 What is Biamping? Biwiring?
	Most speakers are connected to an amplifier by one pair
	of terminals on each speaker. Within these speakers, a
	crossover distributes the signal (modified appropriately)
	to each of the drivers in the speaker.

	Some speakers are set up to be either biwired or biamped. A
	much smaller number allows triwiring and triamping.  The same
	principles apply but use three sets of wires or three amplifiers
	instead of two.  Most speakers that support biamping/biwiring
	have two pairs of terminals and some mechanism for shorting
	the two pairs together when used in the normal way. This
	mechanism is most likely a switch or a bus bar. To help
	the descriptions below, I will refer to these two pairs as
	LO and HI  (because normally one pair connects to the woofer
	and the other pair connects to the tweeter/midrange).

	Biwiring means that a speaker is driven by two pairs of wires
	from the same amplifier output. One cable pair connects HI to
	the amp, and the other cable pair connects LO to the same amp
	output that you connected the HI cable to.  Biwiring is
	controversial; some folks hear a difference, some do not. The
	most plausible explanation involves magnetic induction of noise
	in the relatively low current HI cable from the relatively high
	current signal in the LO cable.  Accordingly, Vandersteen
	recommends the two cable pairs for a channel be separated by at
	least a few inches. In any case, the effect appears to be small.

	Biamping means that the two pairs of terminals on a speaker are
	connected to distinct amplifier outputs. Assuming you have two
	stereo amplifiers, you have two choices: either an amp per
	channel, or an amp per driver. For the amp per channel, you
	connect each terminal pair to a different channel on the amp
	(for example, the left output connects to HI and the right side
	to LO). In the other configuration, one amp connects to the LO
	terminals, and the other amp is connected to the HI terminals.

	The point of biamping is that most of the power required to
	drive the speakers is used for low frequencies. Bimaping allows
	you to use amps specialized for each of these uses, such
	as a big solid-state amplifier for the LO drivers and higher
	quality (but lower power) amp for the higher frequencies.
	When you have two identical stereo amps, some folks
	recommend distributing the low-frequency load by using an amp
	per channel.  In any case, whenever you use two different
	amplifiers, be careful to match levels between them.

	Biamping also allows you to use high-quality electronic
	crossovers and drive the speaker's drivers (the voice coils)
	directly, without the series resistance and non-linear
	inductance of a passive crossover.  Biamping which uses the
	speaker's crossover is therefore much less desirable.  Replacing
	a good speaker's crossover with an electronic crossover has
	advantages, but involves some very critical tradeoffs and tuning
	which is best left to those well-equipped or experienced.
	
	See also section 16.0 below, on wire and connectors in general.

10.2 Can amplifier X drive 2 ohm or 4 ohm speakers?
	Almost any amplifier can drive almost any load if you don't turn
	the volume up too high.  Tube amplifiers are one exception.
	Some amps clip if you play them too loud.  This is bad and
	damages speakers.  Other amplifiers shutdown if they are asked
	to play too loud.  Many will overheat, with bad consequences.
	However, in almost all cases, it takes seriously loud sound or
	low speaker resistance (less than 4 ohms) to do damage.  Running
	two sets of 8 ohm speakers at once with common amplifiers
	represents a 4 ohm load.  Four sets of 8 ohm speakers makes a 2
	ohm load.  Two sets of 4 ohm speakers also makes a 2 ohm load.
	If you stay sober and don't turn it up past the point where it
	distorts, you are PROBABLY safe with most amplifiers and most
	loads.  See 10.3 for more information.

10.3 How do I drive more than two speakers with one stereo amplifier?
	One amp can drive many speakers.  However, there are two limits
	to this practice.  The first is that you can overheat or damage
	an amplifier if you drive too low of an impedance to loud
	listening levels.  Avoid loading any amplifier with a lower
	impedance than recommended.  Adding two speakers to one amp
	output loads that output with half the impedance of one speaker.
	(See also 10.2 above)

	The second is that with tube amplifiers, which are uncommon in
	today's common system, it is important that the speaker
	impedance and the amplifier output impedance be well matched.

	When driving two or more speakers from one amp output, always
	wire them in parallel, rather than series.  Series connection,
	while safe in terms of impedance levels, can hurt sound quality
	by raising the impedance that the speakers themselves see.

	Many amplifiers have connectors for two pairs of speakers.  In
	general, these amplifiers also have a speaker selector switch.
	These amplifiers almost exclusively connect the speakers in
	parallel when both are selected.  It is common for these
	amplifiers to specify 8 ohm speakers only.  The reason that they
	specify 8 ohm speakers is because the amplifier is built to
	drive either 4 or 8 ohms, and two sets of 8 ohm speakers loads
	the amplifier as if it were one set of 4 ohm speakers.  It is
	probably perfectly safe to connect one set of 4 ohm speakers to
	an amplifier with two sets of outputs, provided that you NEVER
	use the second set for any set of speakers.

10.4 How big an amplifier do I need?
	Unfortunately, amplifier power ratings and speaker power ratings
	are almost always misleading.  Sometimes, they are factually
	wrong.  Speaker ratings are almost useless in evaluating needs.

	More importantly, human hearing is sensitive to the log of the
	power coming out of the speaker.  This means that the perceived
	difference between an 80 watt amplifier and a 100 watt
	amplifier, all else equal, is very small. (under 1 dB!)

	There is a wide variation in the "efficiency" and "sensitivity"
	of the various speakers available.  I have seen good speakers
	with under 80 dB per watt efficiency and have also seen good
	speakers with over 96 dB per watt efficiency, measured one meter
	from the speaker.  This difference of 16 dB represents a factor
	of 40 difference in power requirement!

	So the first step in determining amplifier requirements is to
	estimate relative speaker efficiency.  Other factors include how
	loud you will want to listen, how large your room is, and how
	many speakers you will drive with one amplifier.  This
	information will give you a rough starting point.  For an
	example, a typical home speaker will produce 88 dB at 1 watt.
	In an average room, a person with average tastes will be happy
	with this speaker and a good 20 watt per channel amplifier.
	Someone who listens to loud music or wants very clean
	reproduction of the dynamics of music will want more power.
	Someone with less efficient speakers or a large room will also
	want more power.

	Past that point, you will have to use your ears.  As with all
	other decisions, your best bet is to get some candidates, borrow
	them from a friendly dealer, take them home, and listen to them
	at your normal and loudest listening level.  See if they play
	cleanly when cranked up as loud as you will ever go, into your
	speakers in your room.  Of course, it is also important to be
	sure that the amp sounds clean at lower listening levels.

10.5 Do all amplifiers with the same specifications sound alike?
	Some say that they do.  Some say that they don't.  Some
	demonstrated that many amplifier differences can be traced to
	very slight frequency response difference.  Let your own ears
	guide you.  If you want to compare amplifiers, you can do it
	best in a controlled environment, such as your home, with your
	music and your speakers.  Also be very careful to match levels
	precisely.  All you need to match levels of amplifiers is a high
	input-impedance digital voltmeter set to AC volts and a test
	recording or signal generator.

10.6 Is this amplifier too big for that set of speakers?
	There is no such thing as an amplifier that is too big.  Small
	amplifiers are more likely to damage speakers than large ones,
	because small amplifiers are more likely to clip than larger
	ones, at the same listening level.  I have never heard of
	speakers being damaged by an overly large amplifier.  I have
	heard of 100 watt speakers being damaged by a 20 watt
	amplifier, however, in really abusive hands.

10.7 Where can I get a cheap low-power amplifier?
	There are very few available.  One source is to buy a cheap boom
	box and only use the amplifier.  Another source is Radio Shack.
	A third alternative is to buy a car stereo booster and get a 12V
	power supply for it.  Finally, you can build an amp pretty
	easily if you are handy, but it probably won't be that cheap.
	Mark V Electronics, for example, sells 20 watt amp kits for
	under $30 and 80 watt amp kits for under $150.  (See 10.14,
	10.15, and 10.16.)

10.8 Is the stuff sold by Carver really awesome?
	Some people really like it.  Others believe that it doesn't
	perform up to specifications.  Still others believe that it
	isn't all that it is hyped up to be. One of Carver's claims to
	fame is lots of watts per pound of weight.  As with almost
	everything else, the best policy is to listen for yourself and
	see what you think.

10.9 What is a preamplifier?
	A preamplifier is an amplifying electronic circuit which can be
	connected to a low output level device such as a phono cartridge
	or a microphone, and produce a larger electrical voltage at a
	lower impedance, with the correct frequency response.  Phono
	cartridges need both amplification and frequency response
	equalization.  Microphones only need amplification.

	In most audio applications, the term 'preamplifier' is actually
	a misnomer and refers to a device more properly called a

	'control amplifier'.  Its purpose is to provide features such as
	input selection, level control, tape loops, and sometimes, a
	minimal amount of line-stage gain.  These units are not
	preamplifiers in the most technical sense of the word, yet
	everyone calls them that.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: neidorff@uicc.com
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
=========================================================================
    Subject: rec.audio FAQ (part 2 of 4)

Archive-name: AudioFAQ/part2
Last-modified: 1993/3/8
Version: 1.2

10.10 What is a passive preamplifier?
	A passive preamplifier is a control unit without any
	amplification at all. It is a classic oxymoron, because it has
	no capability to increase the gain of the signal.  It is only
	used with line level sources that need no gain beyond unity.

10.11 Do I need a preamp?
	If you have a turntable, you MUST have a (real) preamp, or
	something with a phono preamp section.

	If you don't have a turntable, then the only value in a
	preamplifier is to select the signal source (tuner, CD player,
	etc) and adjust the volume.  If you only listen to CD's, skip
	the preamp entirely.  Get a CD player with a level control and
	connect it straight to a power amplifier.

	If you have a receiver, then the odds are that you already have
	all of the functions of a preamp.

10.12 Should I leave equipment on all of the time or turn it on and off?
	Some gear draws significant electricity, so you will waste money
	and fossile fuel if you leave it on all of the time.  As an
	example, a common amplifier consumes 40 watts at idle.  High-end
	gear uses far more electricity, but ignoring that, 40 watts x
	168 hours x 52 weeks x US $0.0001 per watt hour (rough estimate)
	is $35/year.  Now add a CD player, a preamp, and a tuner, and it
	really adds up.

	High-end enthusiasts claim that equipment needs to warm up to
	sound its best.  If you care about the best sound, give your
	equipment at least 20 minutes to warm up before serious
	listening.  Warm up will allow the inside temperature to
	stabilize, minimizing offsets, bring bias currents up to their
	proper values, and bringing gain up to operating level.

	Either way, good gear will last a very long time.  Tubes are
	known to have a finite life, but good tube designs run tubes
	very conservatively, giving them life exceeding 10 years of
	continuous service.  Some amplifiers run tubes harder to get
	more power out, and thereby may be more economical to turn off
	between use.

	Filter capacitors will fail after enough time at temperature
	with voltage applied.  They will last longer if turned off
	between use.  However, like tubes, filter caps can last tens of
	years of continuous use, as can power transformers,
	semiconductors, and the like.

	Filter capacitors have a funny problem that justified a simple
	break-in or reforming when they are restarted after many years
	of rest.  It involves bringing up the power line voltage slowly
	with a variable transformer.  For tips on reforming capacitors,
	consult "The Radio Amateur's Handbook", by the ARRL.

	Semiconductors seem to fail more often because of bad surges and
	abuse than age.  Leaving gear off may be best for semiconductors
	and other surge-sensitive gear if you expect power line surges,
	as come from an electrical storm or operation of large motors.

	Fuses seem to age with temperature and get noisy, but they are
	so inexpensive that it should not bias your decision.  However,
	some are inconvenient to change, and may require opening the
	case and even voiding the warranty.

10.13 What about swapping op-amps?
	Many amplifiers, receivers, preamplifiers, CD players, and
	mixers use integrated circuits (ICs) called operational
	amplifiers (op amps) as audio amplifiers.  The first op amps had
	a reputation for poor sound quality, especially if misused.
	Some engineers with a strong background in ICs and op amps
	learned that they could improve sound if they replaced slow,
	noisy, low slew-rate, or otherwise bad op amps with better ones.
	Some less informed people tried doing the same thing and made
	the sound worse.

	One pitfall with op amp swapping is that some op amps are more
	prone to unwanted oscillation than others.  The faster the op
	amp, the more likely it will cause an unwanted oscillation,
	which will really damage the sound.  For that reason, Joe may
	succeed in replacing 741 op amps with 5534 op amps in his gear,
	and you may fail in your gear.  It is dependent on the
	individual design, layout, etc.

	As technology and IC design expertise marches on, audio op amps
	are getting better and swapping is getting less and less useful.
	New op amps continue to appear that displace yesterday's best,
	but sound surprisingly similar to straight wire.

	All of that said, some of the better op amps for audio as of
	today include (* means very highly recommended):
		Single		Dual
		AD847		AD827
		AD797*
		NE5534		NE5532
		OP-27		AD712
		LT1115*		LM833
		AD811		NE5535
		AD841		AD842
		HA5112*		OPA2604*
		LT1057		OP249*
		LT1028

	With op amp part numbers, there is a lot of room for confusion.
	Here is a guide to the numbers that is often accurate but
	sometimes wrong:

	Op amp part numbers start with a manufacturer's prefix:
		Analog Devices uses AD
		Burr Brown uses OPA
		Linear Technology uses LT
		Motorola uses MC
		National uses LF and LM
		PMI uses OP
		Signetics uses NE and SE
		TI uses TL
	This can be confused because if TI copies a Signetics op amp,
	they may assume the Signetics prefix, or they may use their own.
	Fortunately, if the part numbers are the same, the circuitry is
	almost exactly the same as is the performance. (Note: almost)

	The next thing in the part number is two, three or four or five
	digits.  This is invariably the key to the part. There are some
	op amps with different numbers that are electrically the same,
	but if the numbers are the same, the parts are almost surely the
	same.  For example, an LM357N and an LM357J are electrically
	identical and will sound the same.

	Next is a letter or two indicating the op amp package and
	possibly how it has been tested and what tests it passed.
	Unfortunately, manufacturers haven't standardized these letters.
	Fortunately, you almost never care.  If it is a dual-inline
	(DIP) package and you are replacing a DIP, you shouldn't have to
	worry whether or not it is ceramic or molded.  Likewise, you
	rarely care if it has 100uV offset or 4mV offset for audio.
	Finally, you don't care if it wasn't tested at elevated
	temperatures because you will use it in your house, inside well
	ventilated gear.

	So in general, an NE5532J is a TL5532N, and an AD827JN will
	sound the same as an AD827LD.  If you aren't sure about some
	detail, call or write the IC maker and ask for a data sheet on
	the parts in question.  They will always send data sheets for
	free, and these data sheets contain details on the various part
	numbers, internal circuitry, and electrical characteristics.

10.14 Where can I buy electronic parts to make an amplifier?
	There are many commercial parts distributors that sell only to
	Corporations.  Their prices are often list, their supply is
	often good, and their service varies.  Common ones are Arrow
	Electronics, Gerber Electronics, Hamilton Avnet, and Schweber
	Electronics.  See your local phone book.

	There are also distributors that cater to smaller buyers  These
	typically have only one office.  Some have lousy selections but
	great prices.  In the following list, (+) means that the dealer
	has a good reputation, (?) means that the dealer has
	insufficient reputation, and (X) means that some have reported
	problems with this dealer. (C) means they have a catalog.

	All Electronics Corporation (Surplus, Tools, Parts) (?) (C)
		PO Box 567
		Van Nuys CA  90408 USA
		800-826-5432
		818-904-0524
	Allied Electronics (Full Line of Parts) (+) (C)
		800-433-5700
	Antique Electronics Supply (Tubes, capacitors, etc) (?)
		688 First St
		Tempe AZ  85281 USA
		602-894-9503
	DigiKey Corporation (Full Line of Parts) (+) (C)
		701 Brooks Avenue South
		PO Box 677
		Thief River Falls MN  56701-0677 USA
		800-344-4539
	Maplin (European Parts) (?) (C)
		+44 702 554161 (For Orders Only)
		+44 702-552911 (Customer Service)
	Marchand Electronics (?) (Crossover kits)
		1334 Robin Hood Lane
		Webster NY  14580 USA
		716-872-5578
	MCM Electronics (Speakers, A/V Repair Parts, Etc) (+) (C)
		650 Congress Park Dr
		Centerville Ohio 45459-4072 USA
		513-434-0031

	MesaBoogie (Tubes, instrument speakers) (?)
		707-778-8823
	Mouser Electronics (Full Line of Parts) (+) (C)
		PO Box 699
		Mansfield TX  76063-0699 USA
		800-346-6873
		817-483-4422
	Newark Electronics (Full Line of Parts) (+) (C)
	Parts Express (Speakers, Cables, Connectors) (+) (C)
		340 East First Street
		Dayton OH  45402-1257 USA
		513-222-0173
	Radio Shack (Parts, Low-End Audio) (+) (C)
	Old Colony Sound (Audio parts and audio kits) (+) (C)
		PO Box 243
		Peterborough NH  03458-0243 USA
		603-924-9464
	Michael Percy (Connectors, MIT, Wonder Caps, Buf-03) (+)
		PO Box 526
		Inverness CA 94936 USA
		415-669-7181 Voice
		415-669-7558 FAX
	Tanner Electronics (Surplus Parts) (+)
		214-242-8702
	Triode Electronics (Tubes, transformers, boxes) (?)
		2010 Roscoe Street
		Chicago IL  60618
		312-871-7459
	Welborne Labs (Connectors, Linear Tech ICs, Wima Caps) (?)
		6836 South Universtiy Blvd. #70
		Littleton CO  80122 USA
		303-470-6585 Voice
		303-791-7856 FAX

10.15 Where can I buy audio amplifier kits?
	Alas, Heath is no longer making Heathkits. Alternatives:
	Audio Synthesis (Many kits from Ben Duncan designs) (?)
		99 Lapwind Lane
		Manchester M20 0UT, UK
		061-434-0126 Voice
		060-225-8431 FAX
	Old Colony Sound (+) (See 10.14)
	Hart Electronics (UK) (?)
	Hafler (+)
	Crimson (UK) (?)
	Mark V Electronics (?)
		8019 E Slauson Ave
		Montebello CA  90640 USA
		800-423-3483
		213-888-8988
	Sonic Frontiers Inc (Tube amp and preamp kits) (?)
		760 Pacific Road Unit #19
		Oakville, Ontario Canada L6L 6M5

10.16 Where can I read more about building amplifiers, preamps, etc.?
	Analog Devices Audio/Video Reference Manual
	Audio Amateur Magazine
		Audio Amateur Publications
		PO Box 494
		Peterborough NH  03458 USA
		603-924-9464
	Audio IC Op-Amp Applications, by Walter Jung
		OpAmp Technical Books
		213-464-4322
	Electronic Music Circuits, by Barry Klein
		Howard D Sams & Co ISBN 0-672-21833-X
|	Electronics Australia (Magazine with audio projects)
|		AUD47 per year 12 issues, often discounted
|		PO Box 199
|		Alexandria, Austrailia
|		+612 353 9944 or +612 353 6666
	Elektor Electronics (How it works and you-build articles)
		(no longer published in US. Still available in Europe)
		PO Box 1414
		Dorchester DT2 8YH, UK
	Enhanced Sound: 22 Electronic Projects for the Audiophile
		(Some basic projects and some "how it works")
		by Richard Kaufman
		Tab Books #3071/McGraw Hill
		ISBN 0-8306-9317-3
	Glass Audio Magazine
		Audio Amateur Publications
		PO Box 494
		Peterborough NH  03458 USA
		603-924-9464
	IC Op-Amp Cookbook by Walter Jung
		OpAmp Technical Books
		213-464-4322
	Journal of the Audio Engineering Society (Theory & Experiment)
		Audio Engineering Society
		60 East 42nd Street
		New York City NY  10165-0075 USA
		212-661-2355
	Popular Electronics					
	Radio-Electronics
	Radiotron Designer's Handbook, Fourth Edition (old, tube info)
	The Technique of Electronic Music, by Thomas H Wells
		Schirmer Books ISBN 0-02-872830-0
	Vacuum Tube Amplifiers, MIT Radiation Lab series
	Wireless World

10.17 What is Amplifier Class A?  What is Class B?  What is Class AB?
	What is Class C?  What is Class D?

	All of these terms refer to the operating characteristics
	of the output stages of amplifiers.

	Briefly, Class A amps sound the best, cost the most, and are the
	least practical. They waste power and return very clean signals.
	Class AB amps dominate the market and can rival the best Class A
	amps in sound quality.  They use far less power than Class A,
	and can be cheaper, smaller, cooler, and lighter.  Class D amps
	are only used for special applications like bass-guitar amps and
	subwoofer amps.  They are even smaller than Class AB amps and
	more efficient, yet are often limited in bandwidth to under
	20kHz (less than full-range audio). Class B and Class C amps are
	not useful for audio.
	
	In the following discussion, we will assume transistor output
	stages, with one transistor per function.  In some amplifiers,
	the output devices are tubes.  Most amplifiers use more than one
	transistor or tube per function in the output stage to increase
	the power level.
	
	Class A refers to an output stage with bias current greater than
	the maximum output current, so that all output transistors are
	always conducting current.  The biggest advantage of Class A
	operation is that it is most linear, in other words, it has the
	lowest distortion.
	
	The biggest disadvantage of Class A is that it is least
	efficient, in other words, it takes a very large Class A
	amplifier to deliver 50 watts, and that amplifier uses
	lots of electricity and gets very hot.
	
	Some high-end amplifiers today are Class A, but traditional
	Class A only accounts for perhaps 10% of the small high-end
	market and none of the middle or lower-end market.
	
	Class B amps have output stages which have zero idle bias
	current.  Typically, a Class B audio amplifier has zero bias
	current in a very small part of the power cycle, to avoid
	nonlinearities.  Class B amplifiers have a significant advantage
	over Class A in efficiency because they use almost no
	electricity with small signals.
	
	Class B amplifiers also have a major disadvantage: very audible
	distortion with small signals.  This distortion can be so bad
	that it is objectionable even with large signals.  This
	distortion is called crossover distortion, because it occurs at
	the point when the output stage crosses between sourcing and
	sinking current.  There are almost no Class B amplifiers on the
	market today, at any price.
	
	Class C amplifiers are similar to Class B in that the output
	stage has zero idle bias current.  However, Class C amplifiers
	have a region of zero idle current which is more than 50% of
	the total supply voltage.  The disadvantages of Class B
	amplifiers are even more evident in Class C amplifiers, so
	Class C is likewise not practical for audio amps.
	
	Class A amplifiers often consist of a driven transistor
	connected from output to positive power supply and a constant
	current transistor connected from output to negative power
	supply.  The signal to the driven transistor modulates the
	output voltage and the output current.  With no input signal,
	the constant bias current flows directly from the positive
	supply to the negative supply, resulting in no output current,
	yet lots of power consumed.
	
	Class B amplifiers consist of a driven transistor connected
	from output to positive power supply and another driven
	transistor connected from output to negative power supply.
	The signal drives one transistor on while the other is off,
	so in a Class B amp, no power is wasted going from the
	positive supply straight to the negative supply.
	
	Class AB amplifiers are almost the same as Class B amplifiers
	in that they have two driven transistors.  However, Class
	AB amplifiers differ from Class B amplifiers in that they
	have a small idle current flowing from positive supply to
	negative supply even when there is no input signal.  This idle
	current slightly increases power consumption, but does not
	increase it anywhere near as much as Class A.  This idle current
	also corrects almost all of the nonlinearity associated with
	crossover distortion.  These amplifiers are called Class AB
	rather than Class A because with large signals, they behave like
	Class B amplifiers, but with small signals, they behave like
	Class A amplifiers.  Most amplifiers on the market are Class AB.
	

	Some good amplifiers today use variations on the above themes.
	For example, some "Class A" amplifiers have both transistors
	driven, yet also have both transistors always on.  A specific
	example of this kind of amplifier is the "Stasis" (TM) amplifier
	topology promoted by Threshold, and used in a few different
	high-end amplifiers.  Stasis (TM) amplifiers are indeed
	Class A, but are not the same as a classic Class A amplifier.
	
	Class D amplifiers use pulse modulation techniques to achieve
	even higher efficiency than Class B amplifiers.  As Class B
	amplifiers used linear regulating transistors to modulate output
	current and voltage, they could never be more efficient than
	50%.  Class D amplifiers use transistors that are either on or
	off, and almost never in-between, so they waste the least amount
	of power.
	
	Obviously, then, Class D amplifiers are more efficient than
	Class A, Class AB, or Class B.  Some Class D amplifiers have
	>80% efficiency at full power.  Class D amplifiers can also have
	low distortion, although not as good as Class AB or Class A.
	
	Class D amplifiers are great for efficiency.  However they are
	awful for other reasons.  It is essential that any Class D amp
	be followed by a passive low-pass filter to remove switching
	noise.  This filter adds phase shift and distortion.  It also
	limits the high frequency performance of the amplifier, such
	that Class D amplifiers rarely have good treble.  The best
	application today for Class D amplifiers is subwoofers.
	
	To make a very good full range Class D amplifier, the switching
	frequency must be well above 40kHz.  Also, the amplifier must be
	followed by a very good low-pass filter that will remove all of
	the switching noise without causing power loss, phase-shift, or
	distortion.  Unfortunately, high switching frequency also means
	significant switching power dissipation.  It also means that the
	chances of radiated noise (which might get into a tuner or phono
	cartridge) is much higher.

11.0 CD Players, CDs, Turntables, and LPs

11.1 What should I listen for when evaluating a turntable or CD player?
	For tape decks and turntables, the major specific problems are
	caused by speed variations (wow and flutter).  A good specific
	check for this is Richard Strauss' 'Also Sprach Zarathustra'
	(also known as the theme from 2001), which has a long, low,
	sustained organ note which comes in well before the main theme
	starts, and is held through the entire first movement.
	Concentrate on that, and make sure it doesn't wobble or warble.
	There's also a good bit for that at the beginning of Pink
	Floyd's 'The Wall', but it doesn't go on as long and so means
	you've got less time to think about it.  Tape decks are
	also prone to losing high-frequency notes, so pick something
	you like which has a lot of treble, and make sure it is clear.

	The sound of a turntable is largely bound up in the kind of
	cartridge mounted on it.  Make sure to listen to a table with
	a cartridge similar to what you're buying, and not one in a
	different price bracket.  If possible, audition the turntable
	with the exact same arm and cartridge, so that you will
	experience potential cartridge/arm interactions, too.  Some
	excellent cartridges work better with one excellent arm than
	another excellent arm.  Treat the tonearm/cartridge pair as a
	coupled system, rather than independent components.

	For CD players, try some piano music.  See if the high notes
	sound tinny.  Also, try something which has some soft parts --
	not the same as turning the volume down.  The distortion
	specification for CD players (as for other devices) is measured
	at a high output level, but in fact in CD players (unlike
	others) it's actually likely to be worse in soft passages of
	music.  This is purely a function of the arithmetic involved.
	Most classical orchestral recordings will contain a suitable
	soft passage.  Most rock music won't.

	The distortion in a CD player, if you want to call it that, is
	a function of the granulation noise, or time-delay pre-echo that
	can come out of the filtering.  To listen for this, use material
	that is rich in high-order harmonics.  Brass music is great for
	this.  Unfortunately, you can't reliably predict how a CD player
	will sound by looking at specifications, features, or the
	technology it uses.  If you want to know how a player will
	sound, you have to listen to it.

11.2 Are some discs better than others?
	Some recordings are better than others.  Some artists are better
	than others.  Some recording engineers are better than others.
	Some microphones are better than others.  Some music is better
	than others.

	Ignoring the above, there is some difference between discs.
	Some of the very earliest discs were badly made and deteriorated
	with time.  The technical problems that caused those problems
	have been solved.  They included ink from the top bleeding into
	the disc, separation of the disc into two thin halfs, and
	oxidation of the metal inside.  Also, some discs were made which
	have aluminum going all the way to the edge of the disk, so are
	more prone to oxidation

	Some "gold" discs are available which are advertised to have
	better life and quality than common "aluminum" discs.  These
	sell for an extra US $20 or more per disc over the cost of the
	same music on a common disc.  Studies have shown that there is
	an advantage to glass-encased, gold platters for archiving
	computer data that is not error tolerant and will need to be
	stored for many tens of years.  I have yet to see a similar
	comparison which justified any extra effort for storing audio
	recordings for 50 years.  Part of the reason for this is that
	audio recordings contain error correction codes.  Another reason
	is that audio recorders can effectively reconstruct badly
	damaged audio data, even if there is data completely missing.

	Some discs seem to have pinholes in the aluminum, which are
	visible when the disc is held up to a strong light.  However,
	these discs play fine and last very well, so the effect of these
	pinholes is probably nil.  Some have performed studies counting
	errors on various discs with various players.  They found that,
	in general, the error count was consistent from one player to
	another.  Also, in general, most discs have a low, consistent
	error rate which is perfectly correctable using the redundant
	data stored on the disc.  This study did find that one group of
	discs had a higher error rate than all of the rest.  This group
	was the promotional discs, also called "music samplers" given
	away by music companies to introduce you to their family of
	artists and performers.  Despite these higher error counts,
	these discs still played fine.

	If there is no abusive handling involved, I have rarely heard of
	a disc that degraded with time.  Of the few that have existed,
	they tended to be from one of the bad batches mentioned earlier.

	There is no doubt that some discs are mastered better than
	others.  Some are badly mixed.  Some are so badly recorded that
	there is noticeable clipping.  Some are made from damaged master
	recordings.  CD technology is no guarantee of good music or of a
	good recording.

11.3 Are CDs better than LPs?
	Some excellent recordings are mastered digitally, and sound
	great on LPs.  This suggests that there is nothing inherently
	bad about digital.

	Some find that LPs sound better than CDs.  Advocates of LPs
	claim that the digital to analog (D/A) converter in home CD
	players isn't up to the quality of the information on the disc.
	They also claim that the analog electronics in a home CD player
	can be poor.

	Some believe that CDs do not sound like LPs because the CD does
	not have the frequency response errors, the distortion, or the
	stereo separation problems of LPs.

	In general, though, there are good and bad CD players, just as
	there are good and bad turntables, cartridges, and tone arms.
	Any ultimate comparison would require ultimate equipment, which
	is unaffordable.  In moderately priced systems, there will be
	some signal damage from the turntable system and some signal
	damage from the CD player.

	LP lovers often learn the nuances of cartridge selection, record
	care, and even turntable and tonearm adjustment.  They have
	found that the turntable will sound different if the arm height
	is adjusted, if the cartridge angles are changed, and if the
	tonearm wire is moved.  CDs do not offer as many avenues for the
	home experimenter.

	However, Audio Amateur Magazine has published modification
	projects for CD players; particularly for Magnavox 560 and
	similar European players.  Audio Magazine has also published
	such articles.

11.4 What turntable should I buy?
	Despite improvements in motor technology, most great turntables
	use belt drive.  Rubber roller (idler) drive sounds the worst.

	Select a turntable with a very heavy platter for the least wow
	and flutter.  Give the platter a rap with your knuckle.  It
	should not "ring" like a cymbal. It should feel and sound dead.

	Also look for a turntable that has good isolation from base to
	stylus.  With the amp on and the turntable selected, but with
	the turntable motor off, put an old record on the turntable,
	lower the stylus onto the record, and then tap the edge of the
	base.  Not too hard, you don't want to send the arm flying.  At
	worst, you should hear (through the speakers) a quick 'thump'
	followed by silence; if you're lucky, you'll hear nothing at
	all.  If the sound continues beyond a quick 'thump', the
	mechanical isolation is not great, and you might want to look at
	some other make.  To perform this test with some turntables, it
	will be necessary to unplug the turntable power cord.


	If the turntable has a tonearm, try to evaluate the arm, too.
	A good arm should be adjustable in height. A good arm should
	allow cartridge adjustments. A good arm should accommodate a
	wide range of cartridges.  Despite this, some arms work better
	with high compliance cartridges, while others are at their best
	with low compliance.  Ask.

	The original AR Turntable was very well received when it was
	first made, and the current AR Turntable is still very respected
	for its price ($450 + arm).  Turntables made by Denon, Linn,
	Rega, Sota, and VPI are also recommended, but can cost more.

11.5 What phono cartridge should I buy for my older turntable?
	The $30 Grado ZTE+1 is a great value for any home user but a
	purist.  For the purist, there are still many choices, both
	moving coil and moving magnet.  Each sounds slightly different,
	and has its individual strengths.  The Sumiko Blue Point has
	been recommended at $125 along with the $125 Denon DL-160 and
	the $150 Shure V15 type V-MR.

11.6 Will phono cartridges still be around ten years from now?
	Most likely, there will still be cartridges available, but not
	in the variety available ten years ago.  They will become
	"Special Order" in some stores and unheard of in others.

	"Pro" or "DJ" cartridges will stay available in good supply,
	"Audiophile" cartridges will stay available and very expensive,
	"Mid-line" cartridges will become very scarce, and a few
	"Budget" cartridges will remain available in copious supply.
	At the same time, some makers will drop their cartridge lines
	completely.

11.7 Will LPs still be around ten years from now?
	There is a strong movement of collectors and purists who will
	keep their collections and buy good used discs.  Count on these
	people to keep the used disc market hot for 25 years longer.

	As for new music, almost none is being pressed today, and the
	art of cutting a master is being lost.  Some rejoice in its
	demise and others are in mourning.

	LP sales have increased recently in Japan and in the UK. Polydor
	is now re-releasing older recordings on vinyl, and will continue
	to press them as long as it is profitable.  Likewise, there are
	several re-releasing projects in Japan.  Some are for Jazz
	collectors and others are for pure analog as well as classical
	music lovers.  They are selling the LPs by subscription, with
	shipments every 2 or 3 months.  Each release includes about 20
	titles.  Japan has released over 100 LPs this way last year.

11.8 What about CD green pens?
	In a nutshell, save your money.

	A CD player "reads" information on the disc with a laser light
	beam.  Some believe that if you put a green stripe on the very
	perimeter of the disc, then the light beam will not reflect
	around inside the disc and will more clearly pick up the data.

	Scientific studies of the data coming off of the disc have
	failed to show any difference between a virgin disc and a green
	painted disc.  I have not heard of double blind listening
	comparisons that have proved that there are people who can hear
	the difference, although many have performed uncontrolled tests
	with positive results.

11.9 What about CD stabilizer rings?
	In a nutshell, save your money.

	The data coming off of the disc is a serial string of ones and
	zeros.  If this bit stream has jitter, then it may reach the D/A
	converter out of sync.  If this happens, then the actual analog
	signal recreated will have jitter, and won't be perfectly true.
	The vendors of stabilizer rings say that using these rings will
	reduce jitter and make a more perfect signal.  Vendors also
	claim that the rings can increase the mass of a disc, making it
	spin more smoothly, and reducing transient load on the power
	supply from the motor.

	Some players will not play discs that have stabilizer rings on
	them.  The clamp can't handle the thickness.  Other players play
	ringed discs, but do not play them well, because the disc motor
	was not built for the added load.

	With those exceptions, scientific studies of the data coming off
	of the disc have failed to show any improvement going from a
	virgin to a ringed disc.  I have not heard of double blind
	comparisons that prove that people hear the difference, either.

11.10 What about CD spray treatments (ArmorAll et al)?
	In a nutshell, save your money.

	Current wisdom is to avoid any disc coating or spray.  Some will
	definitely damage the disc.

	There are many theories on what ArmorAll can do to a disc.  One
	is that it reduces static which will attract the delicate head
	of the laser detector to the disc.  Another theory is that the
	cleaner will fill voids in the disc with silicone, thereby
	making it easier to read by reducing diffraction effects.

	Scientific studies of the data coming off of the disc have
	failed to show any difference between a virgin disc and a
	treated disc.  I have not heard of double blind listening
	comparisons that have proved that there are people who can hear
	the difference.

	One of the strongest proponents of ArmorAll issued a "recall" on
	his advice.  He now warns that ArmorAll can damage the disc.  He
	also advises that you can clean ArmorAll off treated discs with
	Dawn dish detergent.

11.11 Are 1-bit CD players better than multi-bit players?
	In a nutshell, they are virtually the same.

	There are some excellent sounding 1-bit players and some
	excellent sounding multi-bit players.  Some feel that the 1-bit
	technology has more future because it can be improved with the
	rapidly improving digital technology, while the multi-bit
	players improve with slowly improving analog technology.
	Multi-bit also has its advocates.

	All of the various D/A converters try to do the same thing, and
	try to achieve the exact same ideal performance.  How well they
	succeed is more a function of their skill and the quality of the
	parts that they buy than the technique that they use.  In other
	words, the architecture of a D/A converter is less important
	than the quality of its implementation.

11.12 Are three lasers better than one in CD players?
	Some players have one beam, some three.  All use one laser diode
	to generate the beam.  Three-beam is just a different method for
	doing track alignment.  Neither is better than the other.

	There are good 1-beam players and good 3-beam players.
	Manufacturers want advertising claims and "More Beams Is Better"
	sounded good to some marketing people.  Trust your ears.

11.13 Is the BMG 8-for-1 deal good?
	Yes.  You have to put up with their frequent mailings. You can
	elect the "POSITIVE OPTION" and not have to answer each mailing
	to avoid an order.  You should expect to pay approximately $2.00
	per disc for shipping and handling in the US and more elsewhere,
	but even at that price and assuming that you will buy one of
	their discs for $16.00, you still do well.  Assuming, of course,
	that you want at least eight of the discs that they are offering
	for sale.  Some states requires sales tax on BMG sales, and some
	states tax "free" discs, but the tax still is small compared to
	the discount from retail.

	BMG does not have a great selection and tends to sell very
	common titles.  Some rumored that BMG discs are inferior to the
	discs sold in normal retail chains.  This has not been
	substantiated.  In fact, BMG distributes their discs through
	retail chains, as well as through the mail, so you may get a BMG
	disc either way.

11.14 What should I do if there is a problem dealing with BMG?
	The number to reach BMG is 317-542-0414.  Their people have been
	very cooperative with me and others.  It is always good policy
	to confirm any phone call with a letter, restating the problem
	and the resolution you were promised over the phone.  It is good
	practice to write down the name of the person you speak with.

	If BMG sends you something that you didn't order, DON'T OPEN THE
	PACKAGE.  Write REFUSED on the package and put it back in the
	mailbox.  They will accept the return and credit your account
	for any charges.

11.15 How do I get out of the BMG racket?
	If you have taken any discs from BMG, you must either return
	what you have ordered or fulfill the terms of your original
	agreement.  This often means buying one disc at full price and
	paying for the shipping on all discs you ordered and received.

	Once you have done this, you can quit the club at any time.
	Take your next order form and mark it with a bold marker in
	large letters "CANCEL MEMBERSHIP" and mail it to: BMG COMPACT
	DISC CLUB, PO BOX 91413, INDIANAPOLIS, IN  46291 USA.  It may
	take a month to fully take effect, but they will honor your
	request.  While waiting for the cancel order to take effect, be
	sure to return all future order forms marked the same way.
	Otherwise, you may wind up with unwanted discs.

11.16 How do I get the most out of BMG?
	Only buy one disc at full price, fulfilling your obligation.
	Request the "POSITIVE OPTION" so that you save on postage.  Only
	buy from special fliers.  Every month, except November and
	December, they send out a "Two for half price then one free"
	flier.  They have almost all of the stuff in the regular fliers.
	They even offer "Buy one get two free" sometimes.  Wait for

	those special deals.  You can even order discs from an October
	catalog using the order form that came in the February catalog.

11.17 What is a 1-bit (Mash, Bitstream) D/A converter (CD player).

11.18 What is the best under-$200 CD player?
	Once, Magnavox (and the identical Philips) CD players were known
	for poor reliability.  They are much better today.  Some believe
	that for sound, an under-$200 Magnavox is as good as any in its
	price range.  Be sure to listen for yourself before you buy.

11.19 What is the best under-$500 CD player?
	Some recommend the Rotel 855 and 955.

11.20 What's wrong with the CD longbox?
	Some CDs are sold shrink wrapped in a square plastic storage box
	known as the jewel box.  This is the ideal packaging for CDs.
	The shrink lets you know that the disc is new and unopened.
	Other than that, the packaging is minimal.

	Unfortunately, most CDs are sold in a cardboard box that is more
	than 2X the size of the jewel box.  This "long box" is
	ecologically wasteful and useless.  It rarely contains
	additional information about the disc or the artists.  Its
	primary purpose is to discourage theft in retail stores, but it
	is even poor at that.  These boxes are BAD.

	A few stores use a reusable plastic long box.  When you buy a
	disc in one of these boxes, you take the disc and jewel box with
	you and leave the plastic long box with the cashier for reuse.
	Not perfect, but a good compromise.

11.21 How can I promote better CD packaging?
	Vote with your money.  Don't buy CDs packaged in the long box.
	If you go to a store and they have CDs in the long box, tell the
	owner that you never buy CDs in the long box.  Then find stores
	which don't use the disposable long box.

11.22 How can I clean a dirty CD?
	Use a drop of dish detergent and lots of clean water.  Do not
	rub.  Never rub or wipe in a circle.  Rinse the disc in running
	clear water, shake off most remaining drops, and lightly pat dry
	with a soft, clean cloth.

11.23 Can you repair a damaged CD?
	If the disc is lightly scratched on the bottom, then you can
	polish out the scratch and probably repair the disc perfectly.
	If there are lots of scratches or deep scratches, or there is
	damage on the top, you may be facing a lost cause.  The music
	information is immediately under the label.  If you scratched
	the reflective layer, the disc is normally unrecoverable.

	Before trying any repair, try washing the disc with clear water
	and a bit of liquid dish detergent.  Do not scrub or rub hard.
	Rinse the disc with clear water and shake off as much water as
	you can.  Finally, wipe the last few drops off with a soft,
	clean cloth, in a radial direction.

	SMALL scratches can be removed with a scrufty T-shirt and
	toothpaste, such as Tom's Toothpaste.

	You may wish to try a thin coating of Johnson's Klear floor wax
	on the bottom of the CD.  Often it will cover the scratches
	enough to allow playing.  The refractive index is pretty close
	to polycarbonate, so filled scratches will be nearly invisible.

	Noteworthy Music (800-648-7972) sells CD repair kits (#CDR 200,
	$11.99, one shipping unit).  They seem to work as advertised,
	although getting the disc to the point where you can't see any
	sign of the scratch does take real care and persistence.

	You can buy professional plastic polishing compounds at many
	hobby shops.  The ones used for polishing acrylics, plexiglas,
	etc. work.  Ordinary lapidary jeweler's polishes also work.
	You'll need a rough polish to remove the scratches, then tin
	oxide to polish to a mirror finish.  Telescope lens kits also
	work.  Finally, T-Cut, a car paintwork polish, works well for
	big scratches.

11.24 Can I add digital output to a non-digital-out CD player?
	Some Magnavox CD players using the Philips chip set can be
	modified.  Look for a SAA7220 IC.  If it has one, then it can be
	modified.  If you have experience modifying electronic
	equipment, follow this procedure:

	Take pin 14 of the SAA7220 IC and remove whatever terminating
	resistor is on it.  Connect it through a 560 ohm resistor to the
	input of a wide band pulse transformer.  Tie the other end of
	the primary of the transformer to ground.  Pulse Engineering
	PE65612, Schott Corp 6712540, and Scientific Conversions
	SC916-01 all will work.  Bypass the primary through a 620 ohm
	resistor.  Connect the output of the transformer to an RCA jack.
	Do not ground either side of the RCA jack. This output is now
	S/PDIF compatible. (Thanks for the tip to Positive Feedback)

11.25 What can I get in the way of a CD test disc?
	Many use the Hi-Fi News & Record Review test discs.  So far,
	these have received only positive comments.

	Chesky produces 2 test discs.  The first, "Chesky Jazz Sampler
	Volume I" contains some excellent imaging test signals (called
	LEDR), some well-recorded acoustic jazz, and other test signals.
	The second, "Chesky Jazz Sampler Volume II" has similar music &
	different tests.

	Stereophile produces two test discs.  The first seems of limited
	value.  The second just came out.

	Denon also produces two test discs.  The first, "Digital Audio
	Check" is more useful for home use.  The second, "Audio
	Technical" is more for repair shops and test-disc addicts.

11.26 How do the letters ADD on my CD relate to sound quality?
	The simple answer to this question is that there is no relation
	between the three letter code and sound quality.  Those three
	letters refer to the recording and mastering tools used in
	making the CD.

	The first letter refers to the recording process.  For example,
	a disc labeled ADD was ANALOG recorded, where a disc labeled
	DDD was DIGITALLY recorded.  Analog recording means that some
	form of conventional analog tape recorder was used, whether it
	be a two-track home-quality recorder or a very expensive
	wide-tape, high-speed, multi-track recorder.  Digital recording
	could be as simple as a two-track DAT recorder, or can be a
	much fancier multi-track digital recorder.

	The second letter refers to the "mastering" process.  Mastering
	refers to the processing which takes the initial analog or
	digital recording and mixes it down to two-track stereo,
	edits out flaws, equalizes for different sound, adjusts levels,
	and otherwise changes the signal.  All of this can be done with
	digital signal processors, and it can also be done with analog
	signal processors.  There are good machines available for this
	which are analog and good machines which are digital.

	The third letter refers to the final product, which for a CD is
	always a digital product.  I have seen discs that are labelled
|	as AAD, ADD, DAD, and DDD.
|
|	Future releases may not have this three letter code on them
|	because they don't tell you anything that is significant. Also,
|	some codes have been used incorrectly on some discs, which
|	makes the information that much more meaningless.

12.0 High Fidelity Systems
	People frequently use the term "Stereo" to refer to a sound
	reproduction system.  To be more accurate, we will use the term
	High Fidelity System to refer to a pile of equipment including
	at least one source, at least one amplifier, and at least one
	speaker.  Common sources are turntables, CD players, tape
	players, tuners, and receivers.

12.1 What is a receiver?
	A receiver is a tuner, power amplifier, and preamp combined.  A
	common receiver has inputs for a turntable, a CD player, a tape
	deck, and perhaps one or two other sources.  It has selector
	switch(s), tone controls, and a volume control.  A receiver may
	have outputs for two speakers, or for more.

12.2 What is a tuner?
	A tuner is a radio receiver which can not directly connect to
	speakers.  Sometimes, the radio in a tuner is higher quality
	than the radio in a receiver.  A tuner may or may not receive
	the AM broadcast band, but 99.999% will receive the FM broadcast
	band.  Some also receive short wave bands, frequencies used
	principally by non-US stations.

12.3 How should I go about selecting a system?
	If you're looking to buy something, the first step is to figure
	out what you can spend.  If you're looking for a whole system,
	this gets tricky, because you have to allocate amounts for the
	different components.  The most popular current rule-of-thumb
	for a single source system (speakers, amp, 1 something-player)
	is to divide the money about equally among the three parts.  If
	you want several players, you'll have to decide whether they are
	all equally important, and so deserve the same amount of money;
	or whether some are less important, in which case you can spend
	less on them and put the savings elsewhere.

	This rule isn't hard-and-fast.  It's just meant as a starting
	point so you don't have to listen to every possible combination
	of equipment.  If you are building around a CD player, you might
	spend a bit less on the player and a bit more on the speakers.
	If you are buying turntable (or something else which plays by
	physical contact) on the other hand, it might be good idea to
	put a bit extra into the player.  The reason for this is that if
	you skimp on the turntable, then when you come to buy a better
	one you may find that your records have been worn out by the
	cheap player.  If you skimp on the speakers, on the other hand,

	then when you can afford better speakers the music will still be
	there on your records.

	See also 9.1, 9.2, and 11.1 for information on what to listen
	to and what to listen for when evaluating speakers, turntables,
	CD players, tape recorders, and systems in general.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: neidorff@uicc.com
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
=========================================================================
    Subject: rec.audio FAQ (part 3 of 4)

Archive-name: AudioFAQ/part3
Last-modified: 1993/3/8
Version: 1.2

12.4 How can I improve the sound of my stereo?
	The cheapest improvement you can make, and perhaps the most
	effective, is to position your speakers carefully and correctly.
	See 9.4, above.  This will improve the frequency response
	flatness, making it easier to hear every instrument and voice.
	Setting speaker position correctly can also improve the
	three-dimensional recreation of a stereo image.

12.5 Do I want a combo system or separate components?
	Combo systems used to be cheap jokes; that's not always true
	now.  Some sound very nice; there are even some made by
	"audiophile" companies, and they sound even nicer.  They've got
	lots of advantages.  They take up less space.  The controls tend
	to be well-integrated, especially if they are remote-controlled.
	Therefore, they are easy to operate; this can be a major plus if
	some of the people who'll use it are afraid of, or not very good
	at, technology.  Also easy to set up, and don't leave millions
	of wires dangling all over everywhere.

	If you do go for a combo, get a brand name; either an audiophile
	company, or a good "consumer electronics" company.  Brand-X
	combos are generally overpriced and unpleasant.  If possible,
	buy it where you can listen to it first, such as a "real" hi-fi
	shop.  Mid-range hi-fi shops sell combos, as a way of
	introducing beginners to quality sound.

	In most good combos, the speakers are the weak link.  If you do
	go for a combo, you can almost always improve the sound
	drastically by buying a set of better speakers.  Better speakers
	start in the $100-$200 price range.  Some of the best combos
	come without speakers, forcing you to do this.  A good combo
	with replacement speakers will give you very pleasant music.

	Sounds good, you say, so why do people bother with components?
	Well, you can get better sound with a component system -- but
	usually at the expense of convenience and size.  A good
	component system will normally require a mixture of boxes from
	different makers to get the best results, so you've got to spend
	more time listening to things.  However, if you listen to your
	music seriously, then the performance of a component system is
	the reward for that extra work.

	Components are harder to set up and operate.  However, as noted,
	you can get better sound.  You also get more flexibility.  If,
	for example, you decide you want a better CD player, you just
	replace the CD player.  With a combo system, you've got to
	replace the whole system.  If your component tape deck breaks,
	you can remove it from the system and take it in for repair or
	replacement. With a combo, the whole system has to go in for
	repair or be replaced.

	When you want to add some new recording medium to your system
	(laserdisc, VCR, DAT, DCC, MD, ...), if you've got components
	you just go buy the appropriate box.  Many combo systems do not
	have places (or many places) to attach extra bits, so again you
	could be looking at replacing the whole thing.  With a component
	system, you can add a turntable; most modern combos can't cope
	with turntables any more.  Do you have a record collection?

	If you're really not sure, components are the safer bet; if
	you're going to make a mistake, that's probably the better way
	to be wrong.  But, if you're sure that a combo would be best
	for your needs, it can be a totally reasonable choice.

	Now, some people may be tempted by one-maker 'component sets',
	particularly the modern, miniature ones.  They tend to be
	equivalent to combos.  Most use non-standard connections, rather
	than the normal twin phono plug, so that it's likely you can't
	swap or add components anyway.  Even where they use standard
	interconnects, they may rely on non-standard interconnections
	for control purposes.  In a few cases, they also rely on sharing
	power, with a power supply in only one of the boxes and the rest
	taking low-voltage connections from that.  And, no one maker
	makes the best everything.  By default, assume that they will
	have the same disadvantages (and most of the same advantages) as
	combos.  If it's important for it to work with "standard"
	components from other makers, be sure to ask before you buy.

	And, if you're in doubt, go for separate components.

12.6 How can I get better FM radio reception?
	A. Use a (better) antenna. (See 12.7 and 12.8 below)
	B. Use a (more) directional antenna. (See 12.7 and 12.8 below)
	C. Aim your directional antenna.  Rhombics are ungainly to move,
		but Yagis and dipoles are small enough to point right at
		the station.  With the dipole, to tune in a station to
		the East, run the antenna North-South.  With a Yagi,
		point the individual elements North-South with the
		smallest element on the East end.

12.7 How good are these compact FM antennas?
	For receiving, small is ugly.  The bigger the antenna (all else
	equal) the better.  Of course, all else is never equal, but
	these fancy, expensive mini antennas tend to be awful.  Some
	compensate for their small receiving structure with a small
	antenna signal amplifier.  However, the quality of that
	amplifier is often no better than the quality of the amplifier
	in your tuner or receiver, so the antenna just gives you a
	stronger signal, complete with stronger noise.

	All of that said, some compact FM antennas can work better than
	a simple dipole in some situations.  They tend to have an
	internal amplifier, which helps with weak signals.  Some are
	directional.  Some aren't.  If possible, be sure that whatever
	you buy can be returned for a refund if it doesn't work out well
	for you.

12.8 What makes the best FM radio antenna?
	Although there is no "best" antenna for everyone, one of the
	most directional is the "rhombic".  Being very directional, this
	antenna can select one weak station out of many strong ones, or
	one group of stations originating from a general direction.
	This antenna is very long, and made up of four pieces of wire
	with feedline at one end for antenna connections and a resistor
	at the other for termination.  Rhombics for FM broadcast band
	use are at least 15 feet (4.5 meters) long, but can be made
	fairly narrow, less than 3 feet (1 meter) wide.  A more narrow
	antenna will be more directional. A longer antenna will give a
	stronger signal.

	Another very directional antenna is the "yagi", which looks just
	like a common TV antenna.  You can even use a common TV antenna
	as a very good FM antenna.  The FM and TV bands are very close
	together.  It has the advantages of being cheap, directional,
	and easy to rotate.

	One of the simplest and easiest to make antennas is the folded
	dipole, made from 300 ohm twin lead.  It is approx. 58" long.
	This antenna is surprisingly good for receiving signals in a
	moderately strong signal area.  Folded dipoles come with many
	tuners and receivers as a standard accessory.  They are also
	available for approximately $2 at audio and department stores.
	
	Whatever antenna you have, you can often get it to work better
	for specific stations by moving it.  In the case of the folded
	dipole, sometimes it works better vertically, and other times it
	works best horizontally.  Sometimes, you can get that one
	elusive station to come in perfectly if you bend the two ends of
	it at funny angles.  Don't be afraid to experiment.  One
	warning.  As atmospheric conditions change, the best antenna
	placement may also change.

	An excellent reference book on antennas is printed by the
|	American Radio Relay League (ARRL).  It is called The ARRL
|	Antenna Book.  Currently in its 16th edition, it is a 736
|	page large, illustrated paperback.  It costs $20 plus s/h.
	It has fairly complete antenna theory, practical information
	such as charts, drawings, comparisons, and tips on construction
	and adjustment.  The ARRL is founded and chartered as a
	non-profit organization to better amateur radio, and antennas
	are a vital part of amateur radio.
		American Radio Relay League
		225 Main Street
		Newington CT 06111 USA
|		203-666-1541

	Also useful:
		Practical Antenna Handbook by Joseph J. Carr
		Tab Books #3270/McGraw Hill - ISBN 0-8306-3270-3

12.9 What about power line conditioners?
	Each home and each outlet has slightly different power line
	impedance and power line noise.  Each amplifier is effected by
	power line impedance and power line noise differently.  Power
	line conditioners try to reduce this line noise.  Some also
	change the power line impedance in a way which is supposed to be
	better.  We will leave it to your ears to decide if these
	devices help the sound of your system enough to justify their
	expense.

12.10 How can I reduce vibration sensitivity?

12.11 What equipment can I buy that is 100% made in the USA?
	There are many lines of equipment that are carefully hand
	crafted in the USA.  Unfortunately, these systems are usually
	the high-end ones.  Some US companies also make gear in the
|	far east. When in doubt, ask. Some US audio manufacturers are:
|		Adcom (some made in Japan)
|		Audio by Van Alstine
|		Audio Research
|		California Audio Labs (CAL)
|		Carver
|		Jeff Rowland
|		Krell
|		Mark Levinson
|		McCormack

|		McIntosh
|		Parasound
|		Proceed
|		PS Audio
|		Spectral
|		Waida

13.0 Listening Rooms and Houses

13.1 How should I place speakers in my room?  What size room is best?
	You are after two important, distinct goals: flat frequency
	response and good three-dimensional image.  At your disposal is
	the room size, the room shape, speaker height, speaker
	placement, listening position, and room treatments.  Even though
	good speakers are essential to good sound, room effects are also
	extremely important.  In many cases, the differences in room
	effects will be more noticeable than spending twice as much on
	speakers!

	For smoothest bass response, a listening room should be as large
	as possible, have dimensions as unrelated as possible, and
	should be optimally damped.  Although nothing is ever ideal,
	there are a few room dimension ratios that are better for
	listening rooms:
		Height		Width		Length
		1		1.14		1.39
		1		1.28		1.54
		1		1.6		2.33
	If your room isn't shaped like that, don't worry.  These
	effects are not major.

	Also for smooth bass response, woofers should be at distances
	from the nearest three room boundaries that are as different as
	possible.  In some cases, the line dividing the listening room
	into left and right halves must be considered a room boundary.
	Also, for smooth bass response, the listener's ears should be
	at distances from the nearest three room boundaries that are
	as different as possible.

	All of this is essential because a wall near a speaker boosts
	the bass from that speaker at some frequencies.  If a speaker
	is the same distance from three walls, then some frequencies
	will be emphasized much more than others, rather than slightly
	more.

	For best three-dimensional image, a listening room should have
	good symmetry about the plane between the two speakers.  This
	means that if one speaker is in a corner, the other speaker
	must be in a corner.  If this symmetry is not right, the first
	reflection from the wall behind one speaker will be different
	from the first reflection from the wall behind the other speaker
	and critical parts of the stereo signal will be damaged.

	Also, no large object should block the path from speakers to
	listener or from speaker to speaker.  Speakers should be
	elevated so that tweeters are at listener ear height.  The
	distance between speakers should be no greater than the distance
	from each speaker to the listener.  Finally, the tweeters should
	be aimed at the listeners.

	A normal box-shaped listening room with bare walls will have
	"slap echo" which will reduce intelligibility.  A good cure is
	randomly-placed wall hangings consisting of small rugs spaced
	an inch or so away from the wall to increase sound absorption.
	Another cure is convex-shaped art objects on the walls to
	disperse harmful reflections.  If money is available, commercial
	room treatments such as "Tube Traps" and "RPG Diffusers" are
	also valuable, but many of the benefits of these exotic devices
	are available with simpler techniques.

	As a general rule, in a good room, speakers and listener can be
	close to room boundaries with minimal adverse effects.  In a bad
	room, a good strategy is to place both speakers and listener as
	far away from room boundaries as possible.

	An excellent starting point for speaker placement is to measure
	the listening room diagonal dimensions.  Divide that measurement
	by three.  Put each speaker that distance from a corner, on the
	room diagonals.

		I-----------------------------------I
		I                                   I
		I                 L                 I
		I                                   I
		I        S                 S        I
		I                                   I
		I-----------------------------------I

	Place your listening position midway between the two speakers
	and approximately half way from the speakers to the wall.  Be
	sure that there is nothing in the "triangle" formed by the
	listening position and the speakers.

	Try this and then move things 12" (30cm) at a time to see if
	you can improve the sound.  Your ears will be a better guide
	than any commonly-available instruments.  To keep track of
	what you are doing, take notes.  To remember exactly where
	you put the speaker on the floor, a practical trick is to
	mark the floor with a sewing needle and thread.

13.2 How do I wire a house for sound?
	A fundamental principle of physics is that the farther a signal
	travels, the more the signal will be degraded.  Translate this
	to mean that the shorter the wire, the better.  Understanding
	this, the idea of running speaker cable between  every room of
	the house isn't as attractive as it first seems.	

	If you still decide to wire your house for sound, you should do
	it at the same time you're wiring for telephone and electricity.
	It is possible to wire a house after the walls are closed, but
	it becomes very difficult.

	It is economical to use common house wire (Romex, UF, NM, etc)
	for speaker wire in the walls, but this may violate building
	codes.  Check with an electrician or inspector first.  It will
	also confuse future electricians, so label the wire clearly, all
	along its length.

	If you want to make your house like a recording studio, it is
	best to use the techniques of recording studios.  When studios
	run long lengths of sound cable from one room to another, they
	drive the cable with 600 ohm line amplifiers.  They also use
	shielded, twisted-pair cable.  They only connect the shield at
	one end of the cable.  Finally, they use balanced inputs at the
	other end of the cable.

13.3 Where can I read more about listening room construction and tuning?
	"Building a Recording Studio" by Jeff Cooper
		Mix Bookshelf
	"Handbook for Sound Engineers"
	"The Master Handbook of Acoustics" by F Alton Everest
	"Sound Engineering 2nd Edition" by Don and Carolyn Davis;
		Howard W. Sams & Co. (C) 1990
	"Good Sound" by Laura Dearborn
		Introductory, but clear and accurate
	"Sound Recording Handbook" by John M. Woram
		Howard W. Sams & Co. #22583
		Excellent General Reference
	"Audio Technology Fundamentals" by Alan A. Cohen
		Howard W. Sams & Co. #22678
		Overview of Audio Theory
	"Introduction to Professional Recording Techniques"
		by Bruce Bartlett
		Howard W. Sams & Co. #22574
	"Modern Recording Techniques" by Hubar and Runstein
		Howard W. Sams & Co. #22682
	"Sound Studio Production Techniques"
		by Dennis N. Nardantonio
		Tab Books

14.0 Recording
	There are more different recording systems available today than
	ever before.  Digital and analog are both available to the
	consumer.  With the advent of consumer digital recorders, used
	pro analog recorders are becoming available for surprisingly low
	prices.  Now may be the time for you to buy a microphone and
	recorder and make your first!

14.1 What is DAT?  What is its status today?
	DAT (Digital Audio Tape) is currently the standard professional
	digital format for 2-track digital recording.  DAT had a
	short-lived consumer presence, but never "made it".  As digital
	recorders have no tolerance for clipping, using a DAT recorder
	takes a slightly different knack.  The results can be worth it,
	however, as DAT format offers the same resolution and dynamic
	range as CDs.  DATs record for up to 2 hours on a tape, and can
	run at three different sampling rates:  32 kHz, 44.1 kHz
	(for CD), and 48 kHz (the DAT standard).

14.2 What is DCC?  What is its status today?
	DCC is Philips' attempt to modernize the regular cassette.  DCC
	decks can play analog cassettes, and can record new Digital
	Compact Cassettes.  They use stationary heads (DATs use rotary
	heads as do VCR's), and although they are digital, they use
	lossy compression to fit all the data on the cassette.  Although
	DCC sound quality is far better than the 1960 standard cassette,
	the DCC does not have the sound quality present in DAT or CD.
	DCC may be a good choice for consumers who want to assemble mix
	tapes for cars or walkmans, but is not suitable for any
	professional applications.  As of December 1992, DCC is very
	new, DCC equipment is very expensive, and the ultimate future of
	DCC is not assured.

14.3 What about writable compact discs?  What is the status today?
	Recordable CD's are available, but are very expensive.  Blank
	discs sell for approximately $35 each, and the recorders start
	at around $6,000.  These units are mostly used by recording
	studios and other audio professionals.

14.4 What is the best cassette deck under $200?


14.5 What is the best cassette deck under $400?

14.6 What is PASC?  Can I hear the effects?

14.7 What is SCMS?  Can I hear the effects?
	SCMS (Serial Copy Management System) is a copy-protection system
	intended to stop rampant piracy of commercial recordings to
	digital tape.  SCMS allows the home taper to copy from a CD to a
	digital tape, but prevents anyone from digitally copying that
	new digital tape.

	You CANNOT hear SCMS.

14.8 How can I bypass SCMS?
	There are professional devices used by engineers to manipulate
	the digital bitstream, but they cost several hundred dollars and
	are not cost effective for consumers.  If you need to make
	perfect digital copies of digital copies, buy a professional
	digital recorder.  Pro models do not have SCMS, are more durable
	than consumer recorders, and may have better quality electronics
	than consumer models.

14.9 What's this about a tax on DAT?
	Every digital audio tape recorder and every blank digital tape
	sold in the USA is priced to include a "premium" or "tax".  This
	tax is collected by the US Copyright Office and distributed to
	the recording artists and record companies that own the
	copyrights to commercial music.  These fees are supposed to
	repay them for lost royalties.

	Many believe that this "tax" is illegal, because it represents
	an assumption that the buyer will use the recorder and tape to
	violate	a copyright, and not to record their own works.  A
	founding principle of the USA legal system is that everyone is
	assumed innocent until proven guilty.

	If you believe that this law is unjust, write your elected
	representatives.

14.10 Is it legal to copy an LP, CD, or pre-recorded tape?
	In the US today, it may be legal to copy LP's, CD's, etc. for
	your own private use (such as to copy a CD to play on your
	walkman).  UK law specifically prohibits this, but it is almost
	never enforced.  It is definitely not legal in the US, UK, or
	almost anywhere else, to copy these sources for commercial
	purposes, or to give the copies to others.

	It is as of yet unclear whether you own the rights to sell
	or give away a copy of a recording if you made the copy on media
	which was sold with an included digital audio tax.

14.11 How do I clean and demagnetize tape heads?
	First, a caution: DAT recorder tape heads are VERY fragile.
	Before cleaning the heads on a DAT recorder, get specific
	recommendations from a very knowledgeable source that is
	intimately familiar with DAT head cleaning.  In the internet,
	a good source is the DAT-Heads-Digest FAQ.  For more information
	on DAT-Heads-Digest, see section 20.2, below.

	To clean tape heads, use pure isopropyl alcohol and lint-free
	swabs.  Wipe the metal parts of the transport with alcohol
	(DON'T wipe the rollers!) and allow them to dry.  Throw the swab
	away after use.  Be exceedingly careful when cleaning the heads
	on a DAT.  DAT heads are notoriously easy to misalign by
	incorrect cleaning.

	Practical tape head demagnetizers are available for under $10.
	Try to find one with a plastic coated tip.  If you can't find
	one which is plastic coated. you can slip a drinking straw or
	plastic tube over the tip for the same effect.  This plastic
	will prevent the demagnetizer from scratching the head.

	Before plugging in the demagnetizer, remove all tapes from your
	working area and unplug the recorder.  Hold the demagnetizer
	away from the recorder as you plug it in.  Slowly bring the tip
	of the demagnetizer up to the tape head and slide it back and
	forth across each tape head for five one-second strokes.  Then
	pull it away from the head slowly and go on to the next.  After
	demagnetizing the heads, use the tip on each metal tape guide
	with a similar five strokes.  Last, slowly pull the demagnetizer
	far away from the recorder and unplug it.  Recording engineers
	use a demagnetizer before each recording session.

14.12 How do I adjust a tape recorder for best results?
	Adjusting a tape machine for best results usually requires
	special equipment and test tapes.  Unless you know what you're
	doing, leave it for a pro.  If you are serious about doing it,
	buy the service manual for your particular tape recorder.  It
	will list a detailed procedure, as well as describe the correct
	test tape and tools.

	As for setting of record levels, it is best to experiment with
	different levels on different tape brands.  Different
	formulation will reach saturation for different levels.
	Generally speaking, the transients on a Chrome tape should peak
	at about +6 dB above 0, though some formulations can take
	significantly hotter signals.

14.13 Where can I get new pinch rollers or drive belts?
		Projector-Recorder Belt Company
		Whitewater WI USA
		800-558-9572

14.14 What is a good rubber (pinch) roller cleaner?
	Teac RC-1 available from
		J&R Music World
		59-50 Queens-Midtown Expressway
		Maspeth NY 11378-9896 USA
		800-221-8180 or 718-417-3737
	Tascam Rubber Cleaner RC-2 available from:
		Tape Warehouse
		Chamblee GA
		1-404-458-1679

14.15 How can I program a recorder to tape a radio broadcast?
	Radio Shack and Panasonic make a clock/radio/cassette that can
	be set to record at a specific time.  Radio Shack also sells 120
	minute cassettes, which can be used for 60 minutes per side.
	The recorders are not high quality, and the long tapes are
	fragile, but it works.

	You can buy "appliance timers" at hardware stores that will
	start and stop an appliance at a specific time.  Radio Shack
	sells fancier versions of the same thing for more money. Gadget
	freaks love "X-10" control systems.  These can be configured to
	do the same thing.  All require a recorder that can be left in
	RECORD mode.  Such recorders are identified by a "TIMER" switch
	on the front panel.  Many cassette decks have a TIMER switch for
	use with timers.

	Memorex sells a "CP-8 Universal Remote" with a built-in timer.
	Available for approximately $90.00 from either:
		Crutchfield
		1 Crutchfield Park
		Charlottesville VA  22906 USA
		800-955-3000 or 804-973-1811
			or
		J&R Music World
		59-50 Queens-Midtown Expressway
		Maspeth NY 11378-9896 USA
		800-221-8180 or 718-417-3737

	This can be set to start a recorder at a particular time.  As
	the recorder will be started from a remote control rather than
	by the power line voltage, no timer switch is required. Radio
	Shack has a very similar product available for $99.95, may be
	less on sale.

	Damark also sells a learning remote with a built in on/off
	timer and sleep timer. It can learn 17 commands per device on a
	total of 5 devices and should be great for taping a few shows.
	They also sell a 8 device remote with timer.  As Damark sells
	closeouts, these items may not be available in the future.
		Damark
		7101 Winnetka Avenue North
		PO Box 29900
		Minneapolis MN  55429-0900 USA
		800-729-9000 or 612-531-0066

	Use a VCR for audio-only recording.  Hook the audio in to the
	output of a radio, tuner, or receiver.  You may also have to
	connect some video signal to the VCR so that the sync circuits
	work correctly.

14.16 Will CrO2 or Metal tapes damage a deck made for normal tape?
	No.  They will work fine.  They are no more abrasive than common
	tape and may actually be less abrasive than very cheap tapes.
	Recorders which are designed for CrO2 or Metal tape have
	different bias settings and equalization settings to take best
	advantage of the greater headroom and to give flat response with
	these different types of tape.  However, they use similar if not
	identical heads as less expensive tape recorders.  Almost all
	tapes are in some way lubricated, and these lubricants minimize
	wear and squeaking.

14.17 Why do my old tapes squeak in my car cassette deck?
	One problem that will cause this is "binder ooze".  The binder
	is the glue which holds the oxide particles to the backing.
	With time, this binder can ooze forward and actually get past
	the oxide particles, so that there is sticky stuff on the
	surface of the tape.  When this sticky stuff goes past the
	heads, it can cause a slight stick, which will sound like a
	squeak.  You won't feel it with your fingers, but it is there.
	If you have a prized tape with this problem, consider baking
	the tape in a home oven at a very low temperature, like 150F.
	This might cure the problem by drying out the binder.

14.18 Is VHS Hi-Fi sound perfect?  Is Beta Hi-Fi sound perfect?
	The HiFi recording format is subject to two different problems:

	Head-switching noise and compression errors.

	To get perfect reproduction, the FM subcarrier waveform being
	played back by one audio head must perfectly match the waveform
	from the other head at the point of head switching if a glitch
	is to be avoided.  If you record and then play the tape on the
	same VCR under exactly the same conditions, you have a
	reasonable chance of this working.  But if the tape stretches
	just a bit, or you play it on another VCR whose heads are not in
	exactly the same position, or the tracking is off, the waveforms
	will no longer match exactly, and you will get a glitch in the
	recovered waveform every time the heads switch.  This sounds
	like a 60 Hz buzz in the audio, which is often audible through
	headphones even if not through speakers.

	The same glitch will occur in the video waveform too, but since
	head switching always happens during vertical retrace, you won't
	see it.

	The wonderful signal to noise ratio of VHS HiFi is achieved
	through the use of compression before recording and expansion
	after playback.  The actual signal to noise ratio of the tape
	itself is about 35 dB and a 2.5:1 compressor is used to
	"squeeze" things to fit.  Like all companders, this produces
	audible errors at certain places on certain signals, such as
	noise "tails" immediately after the end of particularly loud
	passages.

	Worse, compressors often have problems simply getting levels
	right.  That is, if you record a series of tones, starting at
	-90 dB and working up in 1 dB increments to 0 dB, and then play
	them back, you will almost invariably have level errors.  The
	trend from soft to loud will be there but the steps won't be
	accurate.  Two or three of your tones might come out at
	essentially the same level, then the next one takes a big jump
	to catch up or even overshoot.

	For music, the result will be that the relative levels of some
	instruments, passages, etc. will not be accurate.

	This doesn't matter as much for movies, which tend to have
	steady volume level.  Also, movie enjoyment is rarely hurt by
	these level errors.  VHS and Beta HiFi is fine for reproduction
	of movie and tv soundtracks.  They are also perfectly fine for
	non-critical audio applications.  But VHS and Beta HiFi are not
	serious competitors to DAT, CD, open-reel analog tape, or even a
	high quality cassette deck.

14.19 How do HiFi VCRs compare to cassette recorders?  DAT recorders?
	VHS HiFi and Beta HiFi are analog recording formats which use
	modulation techniques to record a video signal and a stereo
	audio signal on a videocassette.  The audio capabilities
	typically surpass that of the "linear" audio tracks found on all
	video recorders, thus the "HiFi" designation.  "HiFi" is
	essential for getting good sound quality on your video
	recordings and out of pre-recorded videos.

	HiFi is also touted as an excellent audio recorder for
	audio-only (no picture) applications.  On paper, the
	specifications are typically superior to analog cassette but
	inferior to DAT.  In reality, the quality of HiFi video
	recorders is better than low quality cassette recorders but not
	as good as high quality cassette recorders when they are used
	with noise reduction systems.  In no case can a HiFi video
	recorder compare to DAT.  It suffers from generational loss and
	audible noise.
	
	Many people use VHS HiFi for recording radio broadcasts, since
	VCRs often have built-in timers and can record for up to 9
	hours.  If you use a HiFi video recorder to record from an
	audio-only source, beware that some decks will not function
	properly without a video signal for synchronization.  If you are
	interested in very good quality sound, use a deck with manual
	level control.

14.20 What is the difference between VHS HiFi and Beta HiFi?
	VHS HiFi uses "depth modulation"; Beta HiFi uses "frequency
	modulation".

14.21 Is there any good reason to buy a HiFi VCR for common TV shows?
	If you do not own a stereo TV, the purchase of a HiFi VCR will
	give you the capability to listen to stereo TV broadcasts to
	your system.

| 14.22 What is the best cassette tape?
|	One simple answer to this question is that the best tape is the
|	tape which was used to align your tape recorder.  A second
|	simple answer is that more expensive tapes are frequently
|	better in terms of quality of the backing, durability of the
|	oxide, accuracy of the shell and guides, and life.
|
|	Background: When you make a tape recorder, you build electronic
|	circuits which have specific, non-flat frequency response.  These
|	circuits correct for the non-flat response of the tape heads,
|	the recording process, and the tape.  These circuits can be
|	adjusted after the recorder is made, but adjustment is tricky,
|	and may or may not be successful with every tape made.  The
|	designer of the tape recorder picked one tape as their standard
|	when they did the design, and built that recorder to work well
|	with that particular tape.  It may work better with a different
|	tape, but it won't necessarily sound the best with what one
|	person calls the best sounding tape.
|
|	From a review of frequently given answers to this question,
|	it is obvious that almost every brand of tape has its advocates.
|	Many brands also have their detractors.  Maxell and TDK tend to
|	have a strong following, but that is in part because they own a
|	large share of the US tape distribution market.
|
| 14.23 What is the best Reel-to-Reel tape?
|	See 14.22.  Just as cassette tape recorders are set up
|	specifically for one type of tape, reel-to-reel tape recorders
|	are equalized and biased so that they are best with one specific
|	brand and model of tape.  Just as more expensive cassette tapes
|	will last longer and have less noise than cheaper ones, you can
|	expect fewer dropouts, better quality control, and lower noise
|	from more expensive reel-to-reel tapes.
|
|	The major brands in reel-to-reel tape include Ampex, Scotch
|	(3M), AGFA/BASF, and Maxell.
|
| 14.24 What is Type I, Type II, Type III, and Type IV cassette tape?

15.0 Mail Order
	Mail order is appealing.  The general hope is that by using mail
	order, you avoid pushy sales people, you pay fixed, discounted
	prices, and you have written catalog descriptions to help you
	select your purchase.  In practice, most mail order today is
	"phone order", in that the company completes the deal with a
	phone call.  Many of the "mail order" companies don't even have
	price lists or catalogs.  They are just retailers that are
	willing to sell over the phone and ship the merchandise to
	you.  In some cases, retail store sales are better deals than
	mail order.  Don't expect the lowest price from the first place
	you call.  Also, don't expect excellent service from everyone,
	and especially not from the company with the lowest price.

15.1 Who sells brand XXX equipment mail-order?
	Consult the frequent rec.audio mail-order survey published by
	nau@SSESCO.com (William R. Nau) or contact William Nau directly.
|	This survey is also available via FTP in the pub/rec.audio
|	directory of SSESCO.com.  If you have any mail order
|	experiences to share, please send them directly to William Nau.

15.2 Is the stuff sold by DAK really awesome?  Damark?
	DAK buys in large quantities.  They buy what they think
	they can sell.  They buy close-outs as well as new first-line
	merchandise.  They honestly represent their merchandise with
	specifications.  They offer more information on their product,
	if possible, on the phone through their toll free number.
	I know of many people who have bought from DAK and been
	happy. I personally have bought from DAK and been happy.

	Regarding Damark, opinions of people on the net are similar.
	The products are as described, they deliver what they
	say they will, and will take back or replace unsatisfactory
	merchandise.  I have not heard any unsatisfied Damark customers.

	On the other side, the catalog writers at DAK use some very
	flowery language which is intended to lead you to believe
	that they are selling gold for copper prices. In this sense,
	the words in their catalog may be deceptive.

	The DAK people have a good sense of "what the market will bear".
	They price their products to sell, but not to give away money.
	Mail order prices tend to be 10% to 20% less than discount,
	which is 10% to 20% less than retail. DAK has to compete with
	other mail order dealers, such as Damark, but they send out SO
	MANY CATALOGS that they really don't have to cut prices too far
	to sell.

	DAK has recently gone through hard financial times.  This puts
	buyers in some slight risk, because if they go out of business,
	you may get easy warranty service on their products.  I say
	easy because most DAK products are covered by a manufacturer's
	warranty, and you can often get service from the manufacturer
	as well as from DAK.  I believe that DAK is over their slump,
	but I am not sure.  For more on warranties, see 19.1, below.

15.3 Is the stuff sold by Cambridge Sound Works really awesome?

15.4 What should I watch out for when buying mail order?
	Many of the cautions mentioned in warranties (19.1) apply.
	Look for a store which has been around a long time. Look for
	friends which have dealt with the store and been satisfied.
	Look for a store which does not lie or stretch the truth.

15.5 What is gray market?
	See warranties (19.1), below.


15.6 Are there any good mail-order sources for recordings?
	Noteworthy has a good reputation among net readers as a supplier
	of CDs.  They have a range of discs available centered firmly on
	the mainstream, and are reasonable in price.  Shipping is $3.75
	for 1-5 CDs.  They offer over 14,000 different CD titles.  Their
	offerings are all from US labels.  They give a free catalog and
	also have modem software and catalog on floppy discs for $9.95.
		Noteworthy Music, Inc
		17 Airport Road
		Nashua NH  03063 USA
		800-648-7972 Voice
		603-881-5729 Voice
		603-883-9220 FAX
	
	BMG and Columbia also sell CDs mail-order, but have a smaller
	list of offerings and higher prices. However, BMG and Columbia
	have interesting deals to entice new customers.  Read the fine
	print before you sign to be sure that they are right for you.
	BMG and Columbia both have promotional offerings to "members"
	which allow you to buy two or three discs for the price
	of one.  These can be very good deals, if you want what they
	have.  Look at their advertisements in common magazines and
	Sunday newspapers for a better idea of what they carry.  They
	list much of their line in their ad.  Don't expect much more.
	
	Bose Express also sells CDs.  Their reputation so far is very
	knowledgable people, a large collection, and high prices.
|	Their catalog costs $6.00.
|		Bose Express Music
|		The Mountain
|		Framingham MA  01701 USA
|		800-451-2673 or 508-879-1916 Ext. 2008
|
|	Tower Records has a mail order department which also sells CDs.
|	Their classical catalog costs $13.45.  Their other catalog costs
|	$10.45.  Tower is a large retail chain.  Many have bought from
|	their retail outlets happily, but no one has expressed any
|	comments on their mail order service yet.  Contact:
|		Tower Records Mail Order Department
|		692 Broadway
|		New York City, NY 10012  USA
|		800-648-4844 or 800-522-5445

	Another source is Music New Hampshire; 800-234-8458.  They sell
	many $3.79 post-paid sampler CDs and also many independent label
	single-artist discs.  Most single artist discs are $15.00 each.
	Shipping is $3 for 1-3 discs and $5 for 4-up.  Their stuff is
	mostly obscure artists.  They have Rock, Jazz, Classical, Folk,
	Country, and Children's offerings.  Affiliated with CD Review.
		Music New Hampshire - Wayne Green Inc
		70 Route 202N
		Peterborough NH  03458-1107 USA

	If you like the idea of buying CDs by Modem, consider
		The Compact Disc Connection
		1016 East El Camino #322
		Sunnyvale CA  94087 USA
		Voice 408-733-0801
		Modem 212-532-4045 New York City NY
		      312-477-3518 Chicago IL
		      408-730-9015 Sunnyvale CA
		      510-843-1259 Berkeley CA
	They have a collection of over 58,000 CD titles.  People have
	said that their service is excellent.  Prices are fairly good.
	Shipping is $3.50 for orders under $100.00 and free for larger
	orders.  They do not stock anything, but deliver from the
	warehouses of their suppliers.  This means that some items may
	be back ordered or completely discontinued while remaining in
	their on-line data base.  They advertise 94.2% of orders in
|	1992 shipped, though not necessarily immediately.  If you have
|	a modem and enjoy browsing a data base, their data base is a
|	a very enjoyable experience.  However, the phone bill can be
|	quite prohibitive to those calling from out-of-town.

	There have been a couple of music (cd/lp) mailorder lists
	compiled on the net - one older list can be found via anonymous
	ftp to ftp.uwp.edu in the file: /pub/music/misc.mailorder.rmm
	Someone is revising this file and it should be updated or found
	in a new file name there in the future.

	Another list contains vendors that specialize in progrssive
	rock, electronic and experimental music, is maintained by
	Malcolm Humes and posted sporadically to alt.music.progressive,
	rec.music.misc, & rec.music.info.  This also can be ftp'd from
	ft.uwp.edu, in the file: /pub/music/misc/mailorder.progressive

|	Federal Music and Video markets "Discount Coupon Books"
|	featuring two-for-one CDs and Tape deals.  They require payment
|	with the order, which many consider risky.  One company that
|	distributes these coupon books for Federal Music is Reed Music.
|	The price from Federal or Reed Music with the two-for-one deal
|	is comparable to the price from Noteworthy.  So far, no net
|	user has yet related any positive or negative experience with
|	Reed Music or Federal Music and Video.  Federal Music and Video
|	has been in business since 1985, so is probably legit. However,
|	in that they require payment in advance it is probably safer to
|	avoid them completely and use a discounter like Noteworthy.

	When considering mail purchases of CDs, consider shipping costs.
	It is common for people to charge between $1 and $3 per disk for
	"shipping and handling".  This makes mail order less attractive,
	but may be equally balanced by a lack of sales tax.

16.0 Wire
	More than any other topic, speaker cables and equipment
	interconnects seem to use up rec.audio bandwidth echoing the
	same theoretical arguments, testimonials, and opinions.
	Controversy can be stimulating, educational, and also amusing.
	Please try to keep postings aimed at one of those three goals,
	and avoid the insults and emotion.  Also, try to avoid
	echoing a common position or principle, as described below.

16.1 Do speaker cables matter?
	To avoid confusion and repetition, here is some terminology.
	Cables are connectors attached to wires. Wires generally
	have multiple conductors optionally surrounded by a shield and
	outer insulating covering. Cables can introduce noise into the
	signal, act as a filter (and thus change the frequency response
	of the system), and provide nonlinearities from improper
	(intermittent/loose) connections to or between the connectors.

	It is quite scientifically conceivable that some cables do cause
	a difference in sound, because of the differences in DC
	resistance, interconductor capacitance, and connector attachment
	alone.  The effects of exotic conductor weaving and materials
	are not so well established.  In general, these effects (once we
	eliminate DC resistance), seem to be small. However, if your
	system is at least fairly good, then some folks have observed
	(although not in an experimental, double-blind sense)
	significant differences in system performance with different
	cables. The effects are said to be quite system specific; the
	only real guideline is to try them and see which ones seem to
	sound better in your system.

	Roughly speaking, the price ranges for speaker cables is low
	(under $1/ft), medium (under $6-8/ft), and high (up to $100/ft
	and more). Try to arrange it so you can trial such cables; at
	several hundred dollars per set, experiments can be expensive.

	In any system or experiment, it is essential that the
	differences between cables be separated from the differences
	between connectors.

	You should have an EXTREMELY solid connection between cable and
	speaker.  Speakers operate at very low impedances, so that bad
	connections will create significant artifacts or signal losses
	at any power level.  For example, if the connection has a linear
	resistance of just 1 ohm, the speaker damping factor will be
	dramatically reduced, making bass muddy.  If the connection
	contains imperfect metal oxides, then a slightly rectifying
	junction will block the signal, producing compression,
	distortion, and other non-linear effects.

16.2 What speaker cables are available and how good are they?
	There is a wide range of speaker wire available, ranging from
	30ga zip cord (~$.10/ft) to exotic wires costing over $300/ft.
	The material used ranges from copper to oxygen-free copper (OFC)
	to silver. (There are a bunch of others as well.)

16.3 What can I use for budget speaker cables?
	First, a few words on terminology.  Wire is sized by AWG or BS
	gauge number.  Larger numbers represent smaller wire.  AWG 40
	(also called 40 gauge) is as fine as human hair.  AWG 12 is 2mm
	or .081" diameter.  Some wire is classified as solid, because it
	contains one strand per conductor.  Other wire is called
	stranded, because it consists of many strands per conductor.
	Stranded wire is far more flexible than solid wire.  Most wire
	is made from drawn copper.  Some wire is sold that is claimed to
	be made with a process that produces oxygen-free copper.
	Oxygen-free copper has a different metallurgical structure than
	common copper and may or may not conduct current better.

	Some critical listeners have reported excellent sound from large
	diameter solid copper wire, such as home wiring "Romex 12-2".
	At least one expert has said that common 18-gauge solid copper
	hook-up wire sold by Radio Shack also works very well.  Also
	recommended on a budget is Sound King wire, a 12 gauge oxygen
	free copper stranded cable.  This is available from MCM
	Electronics for $.39/ft.

	The scientific literature indicates that small gauge wire
	generally sounds worse than large gauge.  Resistance-related
	effects of the cable can be eliminated by using at least 12
	gauge wire, particularly for long runs.  Of course, shorter runs
	are always preferred, because they come much closer to the ideal
	zero-length wire, with no resistance, no capacitance, no
	inductance, and no change in signal.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: neidorff@uicc.com
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410

=========================================================================
    Subject: rec.audio FAQ (part 4 of 4)

Archive-name: AudioFAQ/part4
Last-modified: 1993/3/8
Version: 1.2

16.4 What can I use for budget speaker connectors?
	The worst connectors are push-down, or spring terminals.  Screw
	terminals with solid copper wire are much better.  Gold-plated
	binding posts and gold spade lugs are inexpensive by audiophile
	standards and are extremely stable.  Binding posts with spade
	lugs can be tightened to get a very good mechanical joint, and
	may offer the lowest electrical resistance of any connector.

	Gold plated banana plugs and jacks are very good speaker
	terminals.  Good ones are more expensive than gold spade lugs,
	however, they also provide a bigger area of contact, and are
	more convenient when you must frequently reconfigure the system.
	Banana plugs should be periodically monitored for corrosion and
	loss of spring tension.  Monster offers a banana-plug connector
	with an expanding center pin that forms an even better
	connection than common gold banana plugs.  At approximately $25
	per pair, the Monster banana plugs aren't a budget connector.

	All else equal, connectors with gold surfaces are better than
	connectors with any other surface.  This is for two reasons.
	First, gold is extremely inert, meaning that unless gold is
	exposed to very harsh chemicals or harsh vapors, it will not
	corrode or oxidize.  It will remain a pure, low-resistance
	conductor.  Second, gold is quite soft, so that if a gold-plated
	connector is squeezed between two metal surfaces, it will deform
	slightly to fill scratches and voids, giving a very broad,
	low-resistance contact area.

	Corrosion of connectors is often a problem.  Gold-plated
	terminals and connectors somewhat avoid this problem; problems
	with other connectors can be mitigated by unplugging and
	replugging the connector on a regular basis, cleaning the
	contact areas with a pencil eraser, or by using a contact
	enhancer such as Cramolin or Tweek.  When you use a contact
	enhancer, be very sure to follow the directions, and avoid
	spreading enhancer about your equipment.

16.5 What about interconnects, such as the cable between tuner and amp?
	Line-level interconnects conduct smaller signals than speaker
	cables; the typical signal ranges from -2V to +2V (the CD
	output standard) with currents in the microamps (the
	corresponding values for speaker cables attached to a largish
	power amp might be -70V to +70V and currents of many amps).
	Line-level interconnects can be divided into single-ended (or
	unbalanced), and balanced interconnects.  Home audio is almost
	always single-ended interconnects.

	Single-ended interconnects almost always use a form of the RCA
	connector (or phono plug). RCA plugs form fair to poor
	connections that degrade with time as corrosion works into the
	metal-metal contact and as the spring tension of the connectors
	relax.  Gold-plating reduces the effect of corrosion and locking
	RCA connectors solve most of the mechanical problems.  However,
	these premium phono connectors are rare and expensive.  For
	example, a gold-plated Vampire locking RCA plug costs
	approximately $23/pair.  If RCA connectors weren't a de facto
	standard, we'd recommend against them.

	Unbalanced interconnect wires vary in geometry, material and
	price.  Cheaper wires have a single conductor (normally
	stranded) and a shield and cost $.20-$2/ft. Medium (complexity
	and price) wires have two conductors (often arranged as a
	twisted pair) surrounded by a shield and cost from about
	$3-$20/ft.  Exotic wires have all sorts of geometries and
	materials (such as stranded silver conductors, or ribbon cable
	braided around a core, or in one extreme case, a tube filled
	with mercury!).  Prices may be as high as $200-$300/ft.

	Balanced interconnects have three conductors: two for the signal
	one for ground, and additionally a shield.  The standard
	connector for balanced cable is the ITT/Cannon XLR connector,
	which is quite good mechanically (they lock).  Equivalent
	connectors are also available from Switchcraft, Neutrik, and
	other vendors.  If you have to run cables longer than 12 feet or
	4 meters, the greater noise immunity of balanced interconnects
	is often a good idea. For this reason, balanced connectors are
	standard equipment in professional installations such as
	studios, public address systems, and broadcast stations.  There
	is not much variation in balanced cables.  The three brands
	mentioned above are known to be rugged, high quality and
	moderately priced. Slightly weaker imported connectors are
	available, but they aren't dramatically cheaper.

	For most systems, the most important aspect of a cable are
	the mechanical reliability of the connectors; in particular,
	the joint between connector and wire, and the joint between
	connector and socket. Typically, interconnect cables are
	short.  It is worth getting just the right length; cables
	often come in .5 meter increments.  With quite good systems,
	some people observe differences in sound between various
	interconnects. This is quite system-specific and the same
	advice as given above applies: try several brands.  Most
	good dealers will loan interconnects for home evaluation.

	In cables where the shield does not carry the signal or ground,
	the shield is normally only connected to ground at one end.
	In systems where there are significant differences between
	ground levels on various components, it may make a difference
	which way such cables are connected.  Typically, the end where
	the shield is grounded should be at the source of the signal.
	Often, such cable has arrows on it pointing in the direction of
	the signal flow.  In any case, try both orientations.

	There are many objective reasons why cables might cause
	differences in sound by interacting with the drivers in the
	signal sources as well as by providing non-linear effects in the
	RCA connector.  Most of these effects are again related to
	interconductor capacitance and resistance, and the quality of
	the shielding provided by the "shield" conductor.  In balanced
	cables the quality of the "twisted pair" inside the shield is
	also important.  One might note that a shield protects from only
	capacitively coupled interference, and not from any magnetic
	field interference.  The twisted pair in a balanced line provide
	some magnetic rejection, as does steel conduit.  However, steel
	conduit has other characteristics which make it undesirable for
	audio in general.

16.6 What about Phono Interconnects:
	Phono interconnects are part of the link between a cartridge on
	a turntable and a preamp (or head amp or receiver). They are a
	special case of line-level interconnects because the signal is
	much lower, typically 1 to 50 millivolts.  They are also
	intended to operate into a higher impedance, typically 47K ohms,
	and form part of the capacitive load for the cartridge.

	The low signal levels mean that the shielding of the cable, and
	the presence of a separate drain/shield are more important, as
	is a good ground.  A separate solid ground should come along
	with the cable as a separate lead co-routed with the cable.

	In addition, the low signal levels make a good solid connection
	to and through the connectors MUCH more important, because of
	the greater sensitivity to low-level nonlinearities.

	Wire capacitance is often ignored in line-level interconnects;
	however, in a phono interconnect, it may constitute half of the
	total capacitive load of the cartridge. Obviously, then, two
	cables with significantly different capacitances should sound
	differently.  In this sense, the "right" cable for one cartridge
	may be too low or high in capacitance for another cartridge.
	
	For low-impedance cartridges (most moving coil cartridges),
	the wire must have low resistance to prevent cartridge unloading
	and frequency-dependent signal loss. In addition, as the
	signal levels are quite low, shielding is important.

	Unfortunately, copper shields do not block stray magnetic
	fields, so in the case of phono cables, careful routing may be
	even more effective at reducing hum than special wire.

16.7 Is there really a difference in digital interconnects?
	There are now three kinds of digital interconnects that connect
	transports to D/A converters: coax, plastic fiber (Toslink) and
	glass fiber (AT&T ST).  In theory, these should sound EXACTLY
	the same (bits are bits).  However, this assumes good circuit
	design (in particular, the clock recovery circuits of the DAC,
	and careful consideration of electronic noise) which may be
	compromised because of cost considerations or ignorance.  Note:
	different signaling schemes are used on plastic and glass fiber.

	In any case, some people claim to hear a difference; of those
	who do, most seem to prefer the glass fiber.  However, the
	technology of fast digital data transmission in consumer
	electronics is evolving very quickly now.  Any specific
	recommendation should be treated with suspicion until the
	industry matures.

16.8 Can I make very good interconnects myself?
	Yes.  You will need to be the judge of whether or not they
	are as good as $100 interconnects, but it is easy to make
	interconnects that are better than the $2.00 set which comes
	with new equipment.

	There are two necessary ingredients: two-conductor shielded
	cable and RCA connectors.  There is a lot of debate over what
	is the best cable, but in general, the lower the capacitance
	per foot, the better.  Choice of insulation is harder.  There
	may be an advantage to polypropylene or teflon over polyester
	or rubber, but even that is debatable.  If you are buying wire
	from an electronics distributor, some have successfully used
	Belden 1192A microphone cable.  It is rubber insulated, so very
	flexible.  Another recommended cable is Belden 8451.  This is
	a polypropylene cable with foil shield.  Finally, consider
	Belden 89182.  This is foamed teflon insulated, so very low
	capacitance, and foil shielded.  If you plan to make a long
	cable, this low capacitance cable may be the best choice.


	There is also a variety of RCA connectors available.  A good
	connector would be gold plated and machined to tight tolerances.
	A poorer connector will not fit as well, will make poorer
	contact as the connecting surface oxides, and will lose its
	springiness with use.

	When wiring the cable to the connector, use one wire for signal,
	(the tip of the RCA connector) and one wire for ground (the
	shell or outer conductor of the RCA connector).

	Some cables use a foil shield which is difficult to solder.
	These cables typically have a drain wire parallel to the foil
	which can be used for soldering.  Others use a braided shield.

	Regardless of which type of wire you have, connect the shield
	or the shield drain wire to ground on only ONE SIDE.  This will
	stop noise picked up by the shield from causing ground noise.

	It can be a fiddly job soldering RCA connectors.  Before you use
	your new cables, check with an ohmmeter or a continuity tester
	to make sure that you have not accidentally sorted the signal
	and ground leads together, either with a stray drop of solder or
	a loose wire strand.

17.0 The Press

17.1 Which magazine should I read?
	Which ever one you like.  None are absolutely objective.
	Here's a list of some common ones:

		Audio Magazine (US $24/year 12 issues.  Mid-fi)
			PO Box 53548
			Boulder CO  80321-2548 USA
			800-274-8808, 303-447-9330
		Audio Critic (US $24/yr 4 issues) (High-end)
			PO Box 978
			Quakertown PA  18951 USA
			215-538-9555
		Audiophile (High-end, High-$$$ Buying Guide,
				Blind reviews)
			Haymarket Trade & Leisure Publications Ltd
			38-42 Hampton Road
			Teddington, Middlesex, TW11 0JE,  UK
			+44 81 943 5000
			US Inquiries should go to:
				Eric Walter Associates
				Box 188
				Berkeley Hts NJ  07922 USA
				201-665-7811
		Car Audio and Electronics ($19.95/year 12 issues)
			Avcom Publishing Ltd
			21700 Oxnard Street
			Suite 1600
			Woodland Hills CA  91367 USA
			818-593-3900
		CD Review (Music Reviews; all tastes, only CDs.)
			$19.97 per year 12 issues
			PO Box 588
			Mount Morris IL  61054 USA
		Hi-Fi Choice (Mid-end. Comparative reviews with graphs,
				tables, and subjective commentary;
				'Buying Guide' section)
			Dennis Publishing Ltd.
			14 Rathbone Place
			London, W1P 1DE, UK
			+44 71 631 1433
		Hi-Fi News and Record Review (Mid-end. Good new record
				reviews)
			Subscriptions Department
			Link House Magazines Ltd
			1st Floor
			Stephenson House, Brunel Centre
			Bletchley, Milton Keynes MK2 2EW, UK
		HiFi Heretic
			PO Box 2019
			Yorba Linda CA  92686 USA
		Hi-Fi World  (Friendly, lower-mid-end magazine)
			(reviews and "how things work" articles)
			Audio Publishing Ltd
			64 Castellain Rd
			Maida Vale
			London  W9 1EX, UK
			+44 71 266 0461
		In Terms Of Music  (Emphasizes music reviews, new)
			PO Box 268590
			Chicago, IL 60626  USA
			312-262-5918
		International Audio Review
			2449 Dwight Way
			Berkeley CA  94704 USA
		Positive Feedback (Technical articles by big-names)
			Oregon Triode Society
			4106 N.E. Glisan
			Portland OR 97232 USA
		Stereophile (US $35/yr 12 issues) (High-end)
			208 Delgado
			Santa Fe NM  87501 USA
			800-435-0715 or 505-982-2366
		Stereo Review (US $6.97/yr 12 issues.  Lower end/mass
				market)
			PO Box 52033
			Boulder CO  80323-2033 USA
		The Absolute Sound (US $46/yr 8 issues) (High-end)
			Box 6547
			Syracuse NY  13217 USA
			800-825-0061
		The $ensible Sound (Mid and High-end)
			403 Darwin Avenue
			Snyder NY  14226 USA
			716-681-3513
		What Hi-Fi  (Mid-end; comparative, subjective reviews)
				(contains it's own buyer's guide with
				recommendations)
			Haymarket Trade & Leisure Publications Ltd
			38-42 Hampton Road
			Teddington, Middlesex, TW11 0JE, UK
			+44 81 943 5000
			US Enquiries should go to:
				Eric Walter Associates
				Box 188
				Berkeley Heights NJ  07922 USA
				201-665-7811

17.2 Which reviews are better?
	Some reviews are so colorful and exciting, that they make great
	journalism and fun reading.  Lets ignore these for now,
	even though they have their place.
	
	Beware of reviews from magazines that advertise the same
	product.  The likelihood of bias is too high. Unfortunately,
	that rules out 99% of the reviews in magazines.

	Stereo Review has a bad reputation for loving everything
	made by every advertiser.  Even high-end journals such
	as Stereophile and The Absolute Sound can be influenced.

	A classic example of misleading reviews occurs with equipment
	submitted to a magazine for review.  The manufacturer may send
	the editors a carefully built, adjusted piece for review.  The
	magazine will honestly rave about it. The manufacturer will then
	send the design off-shore for more economical manufacture and
	assembly, and the quality will suffer.  Lower quality components
	will be substituted for prime parts.  Adjustments will be made
	to wider tolerances or will not be made at all.  The design may
	be completely changed to make it more manufacturable.  You will
	unknowingly get a completely different piece than reviewed.

	Home auditions with one or two candidates from each of a few
	dealers are your best guide to be sure that you get what you
	want and pay for.

17.3 Is Consumer Reports right?
	Consumer Reports is the most objective testing lab we have ever
	found.  Unfortunately, they are also the world's least
	specialized testing lab.  They market their testing to the
	average consumer.  The average consumer will not hear some of
	the subtle differences which audiophiles hear.  For that reason,
	Consumer Reports ignores issues that others feel vital.

	Consumer Reports also insists on basing their audio testing
	predominantly on lab measurements.  Although lab measurements do
	tell many differences between devices, interpreting lab
	measurements for best sound is difficult or impossible.  For
	example, it is very hard to compare two speaker frequency
	response curves and tell which will sound better.  Some $3000
	speaker frequency response curves look worse than some $600
	speaker curves, even when tested in the same setup.  On the
	other side of the issue, Consumer Reports has improved its test
	methods, and will continue to improve.  Expect the accuracy of
	their reviews to improve with time.

	The Consumer Reports frequency-of-repair data base is larger
	than any similar data base published and can be trusted as well
	as any statistic.

18.0 Retail

18.1 Should I use an up-scale retail store?
	This is probably the best place to listen to gear in a
	controlled environment, next to your home.  This is the best
	place to find expensive, high quality gear.  This is the place
	which is most likely to have a good policy on home trials and a
	liberal return/upgrade policy.  This is also likely to be the
	most expensive place to shop.  One exception to this is that
	these stores have the ability to sell demos, returns, and
	discontinued gear at very advantageous prices.

	Some up-scale dealers will negotiate price on large systems or
	expensive purchases.  It never hurts to ask.


	There are definitely better and worse local hi-fi stores.  If
	you find a really good one, it is probably worth the extra money
	to buy from them, rather than from discounters.  A really good
	store will not push you to buy what they want to sell.  A really
	good store will allow you to take your time with your decision.
	A really good store will not distort the truth in describing
	equipment.  A really good store will help you get the most out
	of your purchase by showing you how to set it up.  They will
	tell you what placement works best for the speakers.  (Don't
	believe them if they tell you to put them anywhere.)  A really
	good store also selects their lines carefully.  They don't want
	dissatisfied customers or warranty returns any more than you do.

	Due to the nature of the customer, a hi-fi store in a shopping
	mall is likely to use high-pressure sales techniques.  They know
	that the majority of their customers are distracted easily by
	299 other stores.  Most of their sales go to customers that come
	in for 3 minutes, select something, and leave.  There are
	exceptions to this, of course, but if there was a good
	generalization, it would be to look elsewhere.  There are stores
	in large buildings, small buildings, private homes, shopping
	plazas, and every other conceivable venue.  Search from among
	these to find one that meets your needs and fits your style.

18.2 Should I use a discount store?
	If you need to listen carefully before making up your mind,
	discount stores can be very frustrating.  If you know exactly
	what you want, then this can be a great place to save money.
	Don't expect knowledgeable sales help or after-sale support.  Be
	sure to ask about the warranty  (see 19.1 below on warranties).

18.3 Is it right to negotiate price?
	Most people feel that it is fair to negotiate.  Some feel that
	it is fair to lie in negotiating, as the sales people frequently
	lie to you also.  Others think that lying to get a lower price
	is an immoral practice.  It may even be illegal, an act of
	fraud.

	Some people feel that if you negotiate over price, you encourage
	stores to mark prices artificially high, so that the stores have
	room to negotiate.  Others feel that in negotiating, you are
	asking the store to accept a lower profit, or asking the sales
	person to take a lower commission and are directly hurting them.

18.4 How can I negotiate price effectively?
	A great source of information on this topic is available from
	books on buying a new or used car.  However, some very helpful
	general tips include:
		Know the competition and the dealer.
		Know the gear.
		Know the prices available elsewhere.
		Believe in your research, not their words.
		Stand your ground.
		Be nice to the people but hard on the deal.
		Be prepared to walk away if they won't agree.
		Expect their lines and prepare responses in advance.
			For example, expect the dealer to claim that the
			Nakamichi deck is the best cassette deck on the
			market.  Be ready with a reply such as at that
			price, you can buy a DAT machine which has
			better frequency response, lower signal to noise
			ratio, etc.

18.5 It sounded great in the store.  Is it great?
	Never let anyone else pick stereo for you.  Especially not
	speakers.  They all sound different, and you don't need a golden
	ear to hear the differences.  Listen for yourself and ignore
	what the sales people say.

	If you are still unsure, ask the sales people to let you take
	the gear home for a home trial in exchange for a large deposit.
	Home auditioning takes 99% of the risk out of store auditions.

18.6 Do sales people try to trick the customer?
	Some do and some don't.  Some will treat unpleasant customers
	badly and treat friendly people well.  Most sales people aren't
	wealthy.  They sell stereo to make a living.  If they can sell
	you a more expensive piece of equipment or a piece of equipment
	with a higher profit, they will make more money.  Usually, this
	figures into everything they say.  Some sales people claim to be
	altruistic.

	Some sales people really are open and honest.  They may starve
	with this approach, or they may have a nice enough personality,
	a good enough product line, a good enough store behind them, or
	enough technical background to overcome this "limitation".

18.7 How can sales people trick the customer?
	Often, a customer will trick him or herself without help.  We
	are often swayed by appearance, sales literature, position of
	the equipment in the show room, and our own desire to buy what
	others will like.

	Some times, the sales person will actively try to push a
	particular piece of equipment by demonstrating it against
	another piece of equipment which is inferior or defective.

	Some sales people will demonstrate a set of speakers while
	simultaneously driving a subwoofer, even though they are not
	telling you this.  With the subwoofer, it probably will sound
	better.

	Some sales people will demonstrate one set of speakers louder
	than others.  Louder almost always sounds better.

	Most stereo buyers go into the store, spend a few minutes
	selecting what they want, lay down big bucks, and leave.  They
	don't need to be tricked.  They don't listen carefully.  They
	trust the sales person's choice as best in their price range.
	For non-technical reasons, these people are the most likely to
	be satisfied with their purchase.

18.8 What should I ask the sales person?
	What do you want to know?  Seriously, the best questions are
	those which the sales person can answer without distorting the
	truth.  Don't ask a sales person to compare their brand to a
	brand they don't sell.  Don't ask "how good is the ...".  Ask
	questions of fact.

	Here are some questions you may want to ask:
		If I don't like it can I return it for a full refund?
		Can I try this out at my home in exchange for a deposit?
		What does the warranty cover?  For how long?
		What do I need to know to set this up for best sound?
		Do I get a manufacturer's warranty with this?
		Where do I take this to get it repaired under warranty?
		Where do I take this to get it repaired out of warranty?

18.9 How do I impress the sales person?
	Why would you want to?  You have money and he doesn't.

18.10 How do I get the best service from a sales person?
	Be honest with the sales person.  Set some reasonable request
	and ask them to meet it.  For example, say that you will buy
	this if you can try it at home first and listen to it
	side-by-side with a piece from another store.  Alternately, say
	that you saw the same thing at store Z for $xx less, but you
	will buy it from the guy if he will match the price.

19.0 Miscellaneous

19.1 What do I need to know about warranties?
	Warranties have a few basic components.  The first is the term
	of the warranty.  The second is what is covered.  The third is
	who supports the warranty. The fourth is what restrictions.

	Term is fairly self evident.  What is covered is more detailed.
	In audio electronics, typically everything is covered with a
	"parts and labor" warranty.  Often mechanical components such as
	tape heads are covered by different terms, such as shorter terms
	on labor and longer terms on parts.  Likewise, speaker
	warranties vary widely, from unconditional with no term limit to
	a basic 30 days parts and labor.

	Some warranties come from the manufacturer.  Others come from
	the dealer.  Still other warranty support is available with
	certain premium charge cards.

	A common restriction on some warranties is that the equipment is
	not covered unless it is sold by an authorized dealer.  A few
	dealers have lied about being authorized dealers.  Equipment
	sold by an unauthorized dealer is almost always sold completely
	legally.  This unauthorized dealer may, in fact, be fully
	authorized to sell, but not authorized to sell manufacturer's
	warranties.  In buying gear this way, dealers can get it
	cheaper, and provide the service themselves.  This kind of gear,
	with a full warranty from the dealer is referred to as gray
	market equipment.  Manufacturers discourage buying from these
	gray market dealers, but the risks are fairly low.  If the
	dealer is local and well established, the risks are minimal.

	If you buy equipment mail-order, a dealer warranty may be a pain
	in the neck, especially if you have to ship the gear to the
	dealer more than once to get it fixed correctly.  Then again,
	some factory service requires shipping gear far away at your
	expense, too.

	Frequently, home audio equipment is sold with a warranty
	restriction that if the gear is used commercially or in any
	profit-making enterprise, then the warranty is void. This is to
	protect the manufacturer from having to frequently repair
	equipment meant for light service.  Professional audio equipment
	often comes with very liberal warranty terms, such as lifetime
	parts and labor.  Professional gear takes heavy use and severe
	wear from constant transportation.  It is expected to be able to
	take this abuse.

	All gear, electronic and mechanical, is known to have three
	principal failure modes: abuse, infant failure, and end-of-life

	failure.  In addition, a few of the failures occur at random.

	Infant failure occurs in the first fifty hours of use, and is
	the principal responsibility of warranties. Infant failure is
	frequently caused by defective parts or a design defect.

	Abuse failure is that caused by a person who pulls a cable too
	hard, bangs the equipment on the table, pushes the controls too
	firmly or too fast, or does anything else which the manufacturer
	did  not expect. These are the gray areas of warranties.  They
	do not represent a manufacturing defect in the manufacturer's
	eyes, but they do leave you with a broken device.  To get
	the best chance of coverage against this kind of failure, select
	a brand or a dealer with a very liberal warranty policy.

	End-of-life failures are rarely covered by warranty.  Tape heads
	have a finite, calculable life, as do rubber rollers, speakers,
	cables, batteries, bearings, and motors.  The life of some of
	these components can be extended by intelligent care.  For
	example, the life of common rechargeable batteries can be
	extended by good recharging practice.  Likewise, some cleaners
	can dry out rubber, and will lead to premature failure. Don't
	expect warranty support for any of these problems, and if you
	get it, feel lucky.

19.2 What is blind testing?  Non-blind?  Double-blind?  ABX?

19.3 Where can I get a service manual for brand XXX?
	The most reliable source of supply is the manufacturer's sales
	office in your country.

19.4 Where can I get good repairs on brand XXX?

19.5 How can I take 115V gear over to a 230V country or vice versa?
	Some equipment is available with an international power supply,
	which can be rewired by any serviceman to either power line
	voltage.  If you expect to be moving abroad, look for this kind
	of equipment.  Often, the same model is available both as US
	only and as International. Some equipment will be rewirable and
	won't say it.

	If you know that your gear is limited to one power line voltage,
	you can order a new power transformer for that receiver, CD
	player, amplifier, or tuner which will be wound differently.
	Contact the manufacturer's local service center.  This can be
	very expensive.  A new  transformer for a 40 watt receiver would
	wholesale for under $25 but cost $75 from a service center.

	Another alternative is to buy a power transformer that will
	convert 115V to 230V and vice versa.  Here are some common
	models and their list prices.  Note that the power ratings are
	total line current multiplied by line voltage (2A at 115V is 230
	watts).  Larger transformers are available for more money.  Some
	of the costlier transformers are constructed with plugs and
	jacks for immediate use.  Those marked * have wire leads and
	need safe connections to be used.

	Before spending money, check into other things about audio in
	the new country.  Broadcast frequencies are slightly different
	in some countries than in others, so a receiver or tuner bought
	in one country may not be able to receive some or all of the
	stations in another country.  The US separates the AM broadcast
	band frequencies by 10kHz while the UK uses 9kHz.  Similarly,
	the US separates FM stations by 200kHz, where the UK has
	stations on a 50kHz spacing pattern.  It MAY be very simple to
	modify a receiver from US to UK spacings, but may not.

	Step Down (230V in, 115V Out)
		MagneTek/Triad	N1X*	50 Watts	$11.83
		Stancor		P-8620*	50 Watts	$14.16
		MagneTek/Triad	N3M	85 Watts	$29.95
		Stancor		P-8630	85 Watts	$43.65
		MagneTek/Triad	N6U*	200 Watts	$25.72
		Stancor		P-8632	200 Watts	$51.80
		MagneTek/Triad	N5M	250 Watts	$42.60

	Step Up (115V In, 230V Out)
		Stancor		P-8637	85 Watts	$43.10
		MagneTek/Triad	N150MG	150 Watts	$49.46
		MagneTek/Triad	N250MG	250 Watts	$54.69
		Stancor		P-8639	300 Watts	$55.51

	The Stancor and MagneTek Triad lines are carried by
	large electronic distributors.

19.6 Are there really good deals in country XXX?

19.7 How do I find out how much an XXX is worth?
	There is a "Blue Book" for used audio equipment called
	"Orion Blue Book-Audio".  This guide lists both a
	wholesale and a retail value for most audio gear.
		Orion Research Corporation
		1315 Main Avenue Suite 230
		Durango CO  81301 USA
		303-247-8855
	Last I knew a guide costs $150. Each Nov, a new book is printed.
	After August, the old book is discounted. Some rec.audio readers
	have the Orion Blue Book and will look up gear for others.

19.8 Do people really hear those differences?
	Who knows?  They sure think that they do.

19.9 Why do people disagree on what is the best sound?
	There are at least three different measures of what is "Perfect
	Sound".  All three have advocates, and all three are right, in
	their own way.  In general, whether they admit it or not, most
	listeners fit into one of these three preference groups:

	1.	It must sound like live music.  These people know what
		voices sound like in person, they know what instruments
		sound like without any amplification, and they have
		heard orchestras perform unaided by sound systems.  They
		want to accurately reproduce that sound.

	2.	It must sound like the recording engineer wanted it to
		sound.  The recording engineer listened with extremely
		good equipment to the sound coming out of the
		microphones, and mixed them together for what he, at
		that time, felt was artistically correct.  It may not
		have been the same as live, but it was exactly what he
		wanted.  In the extreme, people like John Fogerty used
		to audition his final recording mix in his truck to see
		how it would sound through a common, lousy stereo.

	3.	It must give me the most pleasure.  No matter how good
		or bad live sounds, no matter what the recording
		engineer intended, if buy some equipment will give me
		more listening pleasure then it must be the best.

	With these three perspectives, it is clear that no one system
	will satisfy everyone.  Add to that confusion the variable that
	everyone likes a different kind of sound, has heard live music
	under different conditions, and has a different idea of what the
	engineer intended.  There is an enormous range of possibilities.

	Another set of reasons is that people look for different things
	to be right.  Some want strong bass; others want male voices to
	sound like  male voices; others want violins to sound like
	violins. Systems rarely do everything equally well. Speakers (in
	particular) are compromises.  Look for the speaker where the
	designer had your priority first.  You are perfectly right to
	select speakers based on YOUR personal taste.

	Confounding the situation further, we all say the greatest
	things about the stuff we already bought.  To do otherwise would
	be to admit that we are either stupid or deaf.

	Still another reason is that most people haven't heard enough
	variations.  Until you hear a system that can truly reconstruct
	the three-dimensional accuracy of a stereo image accurately, you
	may never realize that it is possible.  Some excellent
	recordings contain enough information that with a good enough
	system, you can hear up-down, in-out, and left-right
	distinctions very clearly.  However, we will never experience
	this until we are fortunate enough to hear such a fine recording
	on a very good system.

	Finally, some of us really can't hear much difference.  We
	aren't deaf, but we don't have a well trained ear, don't know
	exactly what to listen for, and may even have slight hearing
	deficiencies, such as bad sensitivity to high frequencies which
	comes with older age, or hearing damage from listening to loud
	sounds (machinery, rock concerts, etc).

| 19.10 How do I contact the manufacturer of XXXXX?  How do I get repair
|		service on XXXXX?  How do I get replacement parts?
|	Some magazines publish lists of contact phone numbers for the
|	manufacturers of equipment.  In the US, Consumer Reports has a
|	small listing in each issue and a more comprehensive listing
|	in their March issue.  Also, Audio Magazine has an exhaustive
|	listing in their October "Equipment Directory".  In Europe, look
|	in "What HiFi?".
|
|	You can find many addresses by reading ads in hifi magazines.
|	You can also find out by asking at your friendly local hifi
|	shop, especially if you've built up a relationship with them.
|
|	repair center.  The best way to locate one near you is to look
|	at the literature which came with your equipment when it was
|	new.  Failing that, see the ideas mentioned above in 19.10.

20.0 Network Protocol

20.1 What are the other newsgroups on audio and music?
	rec.audio.pro: This newsgroup is dedicated to professional
		audio.  It includes discussion on record production,
		studios, studio equipment, DJ equipment, recording
		concerts, sound reinforcement, mastering, mixing,
		special effects, and other topics which might apply to

		audio professionals.  If you are a home audio buff but
		like tape recording, you can find good advice here.
	rec.audio.high-end: This newsgroup caters to audiophiles and
		serious music lovers who are interested in discussing
		the subtle differences between expensive equipment, the
		nuances of selecting the best cables, the love and lore
		of LPs, and other details of audio that are inaudible to
		the untrained ear.
	rec.audio.car: This newsgroup supports discussion on different
		brands and models of car stereo, and also is an open
		forum for talk about car stereo installation, speaker
		selection, custom crossovers, and the special noise
		problems which occur in cars.

20.2 What network mailing lists are out there which aren't on usenet?
	There is an informal group of people interested in using DAT
	recorders to record "Grateful Dead" concerts. These people call
	themselves "Dat-Heads" and have a daily E-Mailing List.  To
	subscribe to this list, send a message to:
		DAT-Heads-Request@fuggles.acc.Virginia.EDU
	asking to join the mailing list.

20.3 Should I post a question about "XXXXXXXXXXXXX"?
	If it is related to professional audio, take it to
	"rec.audio.pro".  If it relates to very expensive audio
	equipment or a request for opinions on subtle sound differences,
	you might want to take it to the newsgroup "rec.audio.high-end".
	Otherwise, if it isn't addressed in the FAQ and it isn't a
	question for one individual, do it!

20.4 How can I suggest a change to the FAQ?
	Send an E-Mail message to neidorff@uicc.com and explain your
	suggestion or correction in detail.

20.5 Where is the FAQ for rec.audio archived?
	This FAQ is available via ftp.  Assuming you have access to the
	internet, the scenario is approximately:
		ftp research.att.com
			# research's IP address is 192.20.225.2
		<login as anonymous; password is your email address>
		cd dist
		get audio.faq
	If you have problems or need further help with accessing the FAQ
	via internet, send e-mail to
                andrew@research.att.com

20.6 What does FAQ stand for?
	FAQ stands for "Frequently Asked Questions".  It is assumed that
	a FAQ also contains FGA or "Frequently Given Answers".  The
	newsgroup rec.audio has very few FGAs due to the personalities
	involved and the nature of audio.  For that reason, this
	document is called a FAQ.

20.7 Why did I get a bitter reply when I posted a simple opinion?
	Some feel that rec.audio is populated by people with very strong
	opinions.  The whole audio industry is filled with opinionated
	people.

	However, for the most part, these people like voicing their
	opinions and reading others.  What may have sounded like a
	severe rebuttal may have instead been an outlet for the other
	person's frustrations or a challenge to you to "play the
	`rec.audio' game" and back up your words with some spirit.

	Be sure to stay light when reading rec.audio.  Otherwise, you
	are likely to take yourself and everyone else too seriously.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: neidorff@uicc.com
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
---
