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Archive-name: AudioFAQ/part1
Last-modified: 1999/11/19
Version: 2.15

1.0 Contents:

Part 1 Intro
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
Part 2 Systems
9.0 High Fidelity Systems
Part 3 Sources
10.0 CD Players, CDs, Turntables, and LPs
Part 4 Amplifiers
11.0 Amplifiers
Part 5 Speakers
12.0 Speakers
Part 6 Rooms
13.0 Listening Rooms and Houses
Part 7 Recording
14.0 Recording
Part 8 Wire
15.0 Wire
Part 9 Retail
16.0 Retail
Part 10 Mail Order
17.0 Mail Order
Part 11 Networking
18.0 Net Protocol
Part 12 The Press
19.0 The Press
Part 13 Misc
20.0 Miscellaneous

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 13 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
as file Mailorder.txt

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. Some of the contributors to this FAQ are listed below.
Others have made great contributions, and are no less appreciated.

andrew@research.att.com (Andrew Hume)
jj@research.att.com (jj)
Ken Kantor of NHT
neidorff@ti.com (Bob Neidorff)
Rick Oakley (no internet access)
DPierce@world.std.com (Richard d Pierce)
P.Smee@bristol.ac.uk (Paul Smee)
gabe@panix.com (Gabe M. Wiener)

6.0 Errors and Corrections:

If you have a correction to the FAQ, additional information, or a new
topic for the FAQ, please send e-mail to neidorff@ti.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 month.

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 in rec.audio newsgroup discussions. At times,
people will make recommendations or suggestions to others on some of
these newsgroups. 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 are 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.

--
Bob Neidorff; Texas Instruments | Internet: neidorff@ti.com
50 Phillippe Cote St | Voice : (US) 603-222-8541
Manchester, NH 03101 USA |

Note: Texas Instruments has openings for Analog and Mixed
Signal Design Engineers in Manchester, New Hampshire. If
interested, please send resume in confidence to address above.

Guest

Archive-name: AudioFAQ/part3
Last-modified: 2000/12/14
Version: 2.15

10.0 CD Players, CDs, Turntables, and LPs

10.1 What should I listen for when evaluating a turntable or CD player?
For tape decks and turntables, beware first of speed variations
(wow and flutter). A good check for this is Richard Strauss'
"Also Sprach Zarathustra" (aka: The Theme From 2001), which has
a long, low, sustained organ note that comes in well before the
main theme starts, and is held through the first movement.
Concentrate on that. Make sure it doesn't wobble or warble.
There's also a good bit at the beginning of Pink Floyd's
"The Wall", but it doesn't go on as long, so you've got less
time to think about it. Tape decks are prone to losing
high-frequency notes, so pick something you like which has lots
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 same arm and cartridge, so that you will experience
potential cartridge/arm interactions, too. Most cartridges
work better with one arm than another. Treat the
tonearm/cartridge pair as a system, rather than independent
parts.

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. Distortion for CD
players (as for other devices) is measured at a high output,
but in fact in CD players (unlike others) it's likely to be
worse in soft passages of music. Most classical recordings
contain a suitable soft passage. Most rock music won't.

Distortion in CD players, 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, such as brass music.
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 MUST listen to it.

10.2 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 that, 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.

Some "gold" discs are available which are advertised to have
better life and quality than common "aluminum" discs. These
sell for an extra US $15 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, allowing a
CD player to perfectly reconstruct minor flaws. Another reason
is that CD players can effectively reconstruct badly damaged
audio data, even if some data is 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.

10.3 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.

10.4 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 will hear a quick 'thump'
followed by silence through the speakers; 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
should look at some other make. When you perform this test,
be sure 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 will be very
rigid and have no bearing play. 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.

Turntables by Denon, Dual, Linn, Michell, Oracle, Pro-Ject,
Rega, Sota, Thorens, and VPI are recommended. If you want a
turntable on a budget, consider the NAD 5120 at approx. $160.

10.5 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. Moving Magnet (MM)
cartridges tend to have higher output than Moving Coil (MC)
cartridges, with exception. Low Output Moving Coil cartridges
require unusual preamplification. Check with a dealer before
buying one. Some candidates:
Sumiko Blue Point $125
Denon DL-160 $125
Shure VST-V $150 (MM, Std Mount)
Audio Technica AT-95E (MM, Std Mount)
Denon DL-100 $85 (MC High Output, Std Mount)
Ortofon MC-10 Super MkI $110 (MC Low Output, Std Mount)

10.6 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.

10.7 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, less is being pressed today than 20 years
ago. Many popular artists are being released on LP in parts
of Europe, but availability is dependent on country. One
person said that many new LPs are available in Spain.

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.

10.8 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.

10.9 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.

10.10 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.

10.11 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.

10.12 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.

10.13 Is the BMG 11-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 11 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.

The BMG collection contains over 2500 discs. This includes
classical, pop, jazz, and other. All BMG discs come from the
larger labels. 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.

BMG has a web site. There is also a great CD Club FAQ on the
web. Try these sites:
http://www.bmgmusicservice.com
ftp://ftp.netcom.com/pub/ra/ramseyms/cd/CD_Club.FAQ

10.14 What should I do if there is a problem dealing with BMG?
The number to reach BMG is 317-692-9200. 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.
You can also contact BMG by FAX at 317-542-6090.

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.

BMG has hired a marketing firm to send out information on the
classical club. Call 800-264-9555, but don't expect customer
service from this number.

10.15 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.

10.16 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.

You can get even more out of BMG by signing up, getting 8 discs
for the price of one, quitting, signing up again, etc. People
have done this successfully. BMG reserves the right to deny
membership to anyone, so you run a very slight risk of being
denied membership the 20th time. However, I have never heard
of anyone ever being denied membership for any reason.

The file CDClubFAQ.txt explains more than you ever wanted to
know about the BMG and Columbia music clubs. It is available
by FTP from: ftp.netcom.com in /pub/ra/ramseyms/cd
or by gopher at: biogopher.wustl.edu An HTML version
can be found at: http://www.blooberry.com/cdfaq/
Online BMG and CH Popular Catalogs are available at:
gopher://biographer.wustl.edu or
http://biogopher.wustl.edu:70/1/audio/bmg
Online BMG Classical Catalog is available by FTP from:
ftp.gmd.de in /music/cd-catalogs
Get file bmg-classical-collection_2ed.gz

10.17 What are the differences between multibit and Bitstream/MASH
Analogue to Digital converters (16-bit vs 1-bit CD players)?

Audio data is stored on CD as 16-bit words. It is the job of
the digital to analogue converter (DAC) to convert these numbers
to a varying voltage. Many DAC chips do this by storing electric
charge in capacitors (like water in buckets) and selectively
emptying these buckets to the analogue ouput, thereby adding
their contents. Others sum the outputs of current or voltage
sources, but the operating principles are otherwise similar.

A multi-bit converter has sixteen buckets corresponding to the
sixteen bits of the input word, and sized 1, 2, 4, 8 ... 32768
charge units. Each word (ie sample) decoded from the disc is
passed directly to the DAC, and those buckets corresponding to
1's in the input word are emptied to the output.

To perform well the bucket sizes have to be accurate to within
+/- half a charge unit; for the larger buckets this represents
a tolerance tighter than 0.01%, which is difficult. Furthermore
the image spectrum from 24kHz to 64kHz must be filtered out,
requiring a complicated, expensive filter.

Alternatively, by using some digital signal processing, the
stream of 16-bit words at 44.1kHz can be transformed to a
stream of shorter words at a higher rate. The two data streams
represent the same signal in the audio band, but the new data
stream has a lot of extra noise in it resulting from the
word length reduction. This extra noise is made to appear
mostly above 20kHz through the use of noise-shaping, and the
oversampling ensures that the first image spectrum occurs at a
much higher frequency than in the multi-bit case.

This new data stream is now converted to an analogue voltage
by a DAC of short word length; subsequently, most of the noise
above 20kHz can be filtered out by a simple analogue filter
without affecting the audio signal.

Typical configurations use 1-bit words at 11.3MHz (256 times
over-sampled), and 4-bit words at 2.8MHz (64 times oversampled).
The former requires one bucket of arbitrary size (very simple);
it is the basis of the Philips Bitstream range of converters.
The latter requires four buckets of sizes 1, 2, 4 and 8 charge
units, but the tolerance on these is relaxed to about 5%.

MASH and other PWM systems are similar to Bitstream, but they
vary the pulse width at the ouput of the digital signal
processor. This can be likened to using a single bucket but with
the provision to part fill it. For example, MASH allows the bucket
to be filled to eleven different depths (this is where they get
3.5 bits from, as 2^(3.5) is approximately eleven).

Lastly it is important to note that these are all simply
different ways of performing the same function. It is easy to
make a lousy CD player based around any of these technologies;
it is rather more difficult to make an excellent one, regardless
of the DAC technology employed. Each of the conversion methods
has its advantages and disadvantages, and as ever it is the job
of the engineer to balance a multitude of parameters to design a
product that represents value for money to the consumer.

All sampling techniques (so also D/A techniques) require an
analog reconstruction filter following the converter. This
filter inherently adds phase shift, frequency response ripple
and high frequency roll-off, depending on the characteristic of
the reconstruction filter (which depends on the position of its
poles and zeros).

An oversampling data converter generates a higher output
sampling rate than a simpler converter, so you can use a more
simple reconstruction filter, which is cheaper and more stable
in time and temperature and produces less noise. Also, modern
oversampling systems include digital filters which compensate
the response of the analog filter in the passband, so you can
achieve systems with an overall performance of 20 Hz...18 kHz
+/-0.05 dB. Also deemphasis is mostly done in the digital
domain.

So the "sound" of a CD player is more than just the number of
bits. It's the quality of the converter, the filter requirements
imposed by that converter, the quality of the filter, and of
course, the quality of the following analog components. Power
supply quality and clock jitter also influence the sound.

10.18 What is the best under-$200 CD player?
In this price range, most manufacturers give you more features
than construction quality or sound quality. If you want a
particular feature, then use that to guide your purchase. If
you are after the best possible sound quality, let your ear
be your guide. Sound quality still varies among models. Don't
trust reviews or advice alone.

10.20 What is the best under-$500 CD player?
Some recommend Rotel. Others recommend Marantz, NAD, or Yamaha.
The industry has made major gains in terms of sound consistancy
in the past years. However, models change every year and there
are models with design flaws. Let your ear be your guide. Also,
don't forget to check quality of construction. In this price
range, you should get more than a flimsy box and more durable
mechanisms than in the <$200 price range.

10.21 (removed)

10.22 (removed)

10.23 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. If you must stroke the disc
do it with a soft cotton cloth in a straight line from the
center outwards (radially). Rinse the disc in running clear
water, shake off most remaining drops, and lightly pat dry
with a soft, clean cloth.

10.24 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.

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. Novus plastic polish and cleaner has been recommended.
T-Cut, a car paintwork polish, works well for big scratches.
Reviewers at Audio Magazine recommend the "Memorex CD Repair
And Maintenance Kit" as the best tool for badly damaged CDs.
Another recommended polish is Meguier's Plastic Polish #17.

Sometimes, a gentle polishing will make a disc playable
even though the scratch is not fully removed. This may be
even better than complete scratch removal because it leaves
more protective plastic behind.

10.25 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)

10.26 What can I get in the way of a CD test disc?
Each test disc offers something different. Some discs contain
useless filler which advertises a product or shows a unique
capability, but really doesn't help you test or improve your
system.

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 three test discs.

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.

If you are looking for test CDs, one source of supply that
stocks lots of different test CDs is:
DB Systems
Main Street
Box 460
Rindge Center NH 03461 USA
603-899-5121

10.27 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 recorder used in the mixing and
editing process. Mixing and editing is the process of combining
a multi-track master recording, setting levels, editing out
defects, adjusting equalization, and creating a two-track final
tape. There are good machines available for this which are
analog and good machines which are digital.

The third letter refers to the final master, which for a CD
is always digital. 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.

10.28 How can I clean LPs?
There are expensive machines for this purpose which work very
well. One popular model goes by the name Nitty Gritty. These
machines spray cleaner onto the record, work it into the
grooves, and then vacuum the cleaner and dirt out. If you are
serious about records and have lots of them, it may be a good
investment for you.

If you have a more reasonable collection, you might be happy
with a good hand washing every now and then. To give your
records a good hand washing, start by preparing this wash:
1 gallon distilled water
1 gram Alconox (a laboratory detergent)
Also, get a natural bristle brush and trim it to the correct
stiffness/bristle length so that the bristles can get into the
grooves but aren't stiff enough to scratch the record.
Some record-cleaning recipies recommend alcohol. However,
alcohol will leach plasticizer from vinyl, and eventually
degrade LPs. Alcohol will also disolve the shellac of 78s,
so should never touch a 78.

Lay the LP flat and pour a thin coat of the above fluid on it.
Brush the wash into the grooves with the bristle brush. Brush
in the direction of the grooves, going through all grooves.
Flush the wash and dirt off with cool, running tap water.
Rinse the record with distilled water and pat it dry
with a soft, clean cotton cloth.

Also consider using a carbon fiber brush every time you play
the LP. It picks up some surface dirt and removes static.

10.29 How do you set the stylus pressure correctly?
Stylus tracking force is typically adjusted at the back of the
tonearm with a knob that is calibrated in grams at the stylus
tip. With the control set to zero, the stylus should sort-of
float above the record surface. The control is then increased
to the number recommended by the cartridge manufacturer.

Do not, under any circumstances, use a lower than recommended
force, as the cartridge may lose the ability to maintain
contact with the groove wall on passages of large amplitude.
This WILL result in RECORD DAMAGE.

If you want the best possible tracking and sound quality, you
will want to fine-tune the tracking force. Use a test record
and listen very carefully, or get the help of a good dealer
with a battery of instruments.

10.30 How do you set the anti-skating on a tonearm?
If you have a recommendation or suggestion from the
tonearm manufacturer, follow their advice first.
They will give you the best starting point.

Some tonearms come with calibrated anti-skate. The manufacturer
of these tonearms has tried to calibrate the anti-skate control
so that if you match the setting of the anti-skate to the
setting of the stylus pressure, you will have nearly perfect
anti-skate. Read the manufacturer's recommendations to see if
this applies to your tonearm.

You can see gross errors in anti-skate by looking at
the stylus. If you shine a light on the front of the
tonearm while playing a record, you will be able
to see whether the stylus is centered in the stylus
holder. If the stylus is biased to one side or another
while playing a record, then the anti-skate is way off.

More subtle adjustments can be made by listening for
mistracking. If you can, obtain a record with equal
left right modulation at high frequency with ascending
modulation magnitude (volume), such as the Shure
ERA-III, IV, or V test record. They have five bands of
"greensleeves" played on flute, and you fiddle until the
audible breakup is equal in both channels, and adjust
tracking weight until it occurs in the highest band.
This is, like other cartridge and tonearm adjustments,
easier for the experienced hand than the beginner.

Some high-end dealers have electronic instruments which
allow them to accurately adjust anti-skate and other
cartridge and tonearm parameters. If you can get this
service, consider yourself fortunate.

10.31 How else do you adjust a tonearm/cartridge/stylus?
There are a few other critical adjustments. Again, a good
high-end dealer may be your best resource. Your ear may
also be your best test instrument.

You need a level turntable. Use a quality carpenter's
level. Some people like the Shure stylus force gage for
setting stylus pressure accurately. Other tools which are
well recommended are the Geo-disk, a good protractor, and
above all, the Cart-Align, which uses a very precise
etched plastic mirror for cantilever alignment.

You'll also want to set the tracking angle. It CAN be
done by eyeball, but is best done with test instrumentation
and a record. There is also the cartridge angle, tonearm
height, etc. Read the instructions which came with your
tonearm for the best specific advice for that tonearm.

Tonearm cable is more critical than any cable anywhere else
in the signal chain. Cable capacitance directly sets the high
frequency characteristics of the cartridge. In addition, the
correct grounding of the shield is essential to minimize hum.
It may be necessary to change preamp input capacitors so that
the cable/preamp combination loads the cartridge with the
right overall capacitance. Replacing tonearm cable will have
a similar effect, but may be harder to change tonearm cable
than to change preamp input capacitors. Consult the
cartridge, tonearm, and preamp manuals for specific advice.
Also refer to 16.6 for more information on tonearm cable.

An excellent article on setting up a turntable is:
Stereophile, July 1990, Pages 62-85.

10.32 Do CDs deteriorate with time? What is their life span?
A CD consists of a polycarbonate top layer, an aluminum (or
gold) metal reflective layer, a polycarbonate bottom layer,
and some miscellaneous printing ink. Of these materials,
polycarbonate seems to be extremely stable with time provided
that it is well cared for. Do not use any liquids on a CD
that contain silicones or solvents. Do not leave CDs in
sunlight or other bright light. Do not stick labels on CDs.
Do not write on CDs. Do not expose CDs to temperatures higher
than normal room temperatures. Don't leave a CD under water.
Even the top side of a CD is critical and subject to damage.

Some pressings from the early 1980s used ink which damaged the
polycarbonate top layer and eventually got into the aluminum.
These inks are not in use today. Some earlier discs were made
with imperfect sealing around the perimeter of the disc. This
was evident because the aluminum in the disc extended all of
the way to the disc edge. These discs were known to fail due
to moisture getting to the aluminum and causing it to oxidize.
Modern CD factories have solved this problem as well.

With those cautions, modern CDs will last for more than 30
years without deterioration. Most of the CDs which were
made in 1983 are still around today and still sound good.

10.33 How much music can you possibly cram into a CD?
The longest seen so far (reported by Stuart Kahler) is a
MiC bootleg of Depeche Mode "Evolution", at 81:09. Next are 'No
Quarter' by Jimmy Page and Robert Plant at 79:38, the collected
singles CD release by The Sisters Of Mercy at 79:30, an MCA
reissue of Steely Dan: Greatest Hits at 79:17 and a Musical
Heritage recording of Bach: Goldberg Variations at 79:02.
Modern CDs are pressed using tighter track spacing than the
first CDs, because modern equipment is capable of holding
tighter tolerance than the original machines.

10.34 What are input and output levels and impedances for signal
sources, preamps, amps, etc?
We have been unable to find any formal standard on this topic.
However, there is an EIA Bulletin: EIA Consumer Products
Engineering Bulletin No 6-A (CPEB6-A) 1974, titled "Preferred
Voltage and Impedance Values for the Interconnection of Audio
Products". The key word in the title is 'Preferred'.

EIA CPEB6-A recommends 3mV at 47k ohms for magnetic phono
cartridges, 250mV at less than 10k ohms for tape and preamp
outputs, and 100k ohm minimum for tape, tuner, and amp aux
inputs. The bulletin also has information on microphones,
and headphones. You can order a copy through a technical
library or directly from the EIA.

10.35 Why are turntable speeds 78 RPM, 45 RPM, etc?
The speeds were chosen because that is the speed that resulted
when you used standard parts. Electric motors rotate at 1800
rpm, most shafts are 1/4". Those combinations with the proper
gears and idlers came out to 78 rpm. In reality it's 78.26
rpm. Tape recorder speeds evolved the same way.

The 78.26 was standardized after electric recording/playback
occured. Prior to that, speeds were "in the neighborhood of"
78 rpm. Some lower and some higher. 80 rpm was used in many
recordings. (Courtesy of Bill Vermillion)

10.36 Why is CD digital data written in 44.1 kHz samples?
The rate of 44.1 kHz was picked to be compatible with existing
50 Hz and 60 Hz video-based digital audio storage, where an
integral number of frame buffers could fit in a single
horizontal scan. Quote from Watkinson and Rumsey, "Digital
Interface Handbook" 2.7.6 Choice of Sampling Rate:

"In 60 Hz [525 line, 60 Hz vertical refresh) video there are 35
blanked lines, leaving 490 lines per frame, or 245 lines per
field for samples. If three samples were stored per line, the
sampling rate becomes 60*245*3=44.1 kHz. In 50 Hz video [625
line, 50 Hz vertical refresh), there are 37 lines of blanking,
leaving 588 active lines per frame, or 294 per field, so the
sampling rate becomes 50*294*3=44.1 kHz. The sampling rate of
44.1 kHz came to be that of the Compact Disk. Even though CD
has no video circuitry, the equipment used to make CD masters
is video based and determined the sampling rate."

The length of 74 minutes is determined by the physical nature
of the reading system. It's based on the encoding method, the
wavelength of the laser used (different wavelengths are
incompatible with current CDs) and the necessary support
information. During the development of the CD, von Karajan was
alledgedly asked how long a CD must be, to which he responded
it must be long enough to hold HIS performance of Beethoven's
9th symphony, but the parameters had pretty much already been
nailed down at that point.

10.37 What's the latest on DVD and DAD?
Check out the articles in The Absolute Sound on the subject,
from issue 112, which is also on the web:
http://www.theabsolutesound.com/dadforum-1.htm
http://www.theabsolutesound.com/dadforum-2.htm
http://www.theabsolutesound.com/dvdhope.htm

10.38 What's the latest on the MiniDisc(tm)?
Check out the MiniDisc(tm) organization web site for a minidisc
FAQ and other MiniDisc(tm) information.
http://www.minidisc.org

10.39 How can I record an LP or tape onto a CD?
That's a complex question, but basically, get a sound card for
your computer, get some cheap software for your computer, and
follow some of the advice at:
http://homepages.nildram.co.uk/~abcomp/lp-cdr.htm

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.

--
Bob Neidorff; Texas Instruments | Internet: neidorff@ti.com
50 Phillippe Cote St | Voice : (US) 603-222-8541
Manchester, NH 03101 USA

Note: Texas Instruments has openings for Analog and Mixed
Signal Design Engineers in Manchester, New Hampshire. If
interested, please send resume in confidence to address above.

Guest

Archive-name: AudioFAQ/part2
Last-modified: 2020/09/04
Version: 2.16

9.0 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.

9.1 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 probably also
has selector switch(s), tone controls, and a volume control. A
receiver may have outputs for two speakers, or for more. Some
receivers do | not have phono preamps, a trend that may become
more common as vinyl loses popularity. Many receivers contain
surround sound processors.

9.2 What is a tuner?
A tuner is a radio reception device which can not drive
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
for long-distance rather than for local commercial broadcasts.

9.3 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.

Another perspective says that you should spend the most you
can on your source, as the sound can never be better than
what you get off of the record/CD.

See also 12.1, 12.2, and 10.1 for information on what to listen
to and what to listen for when evaluating speakers, turntables,
CD players, tape recorders, and systems in general.

9.4 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 13.1, below. 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.

9.5 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.

One-maker 'component sets' are also often of lower quality than
true individual components. Component sets are designed for
convenience and appearance, rather than sound quality.

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

9.6 How can I get better FM radio reception?
A. Use a (better) antenna. (See 9.7 and 9.8 below)
B. Use a (more) directional antenna. (See 9.7 and 9.8 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.

9.7 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. Some have an internal
amplifier, which helps with weak signals if the input stage in
your receiver is poor. 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.

9.8 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.
In addition, very directional antennas are good at reducing
multipath interference, a problem which is more severe in
cities with tall buildings.

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 17th edition, it is a 736
page large, illustrated paperback which includes a disk
of MS-DOS software. It costs $30 plus s/h. It has fairly
complete antenna theory, practical information such as
charts, drawings, comparisons, and tips on construction
and adjustment. ISBN 0-87259-473-4. 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

9.9 What about power line conditioners?
Each home and each outlet has slightly different power line
impedance and power line noise. Each amplifier is affected 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.

9.10 How can I reduce vibration sensitivity?
Some complain that heavy foot falls will cause skipping or more
subtle sonic problems with CD players or turntables. If you
have these problems, there are a few different things which you
can try to reduce the problem. One is to add weight to the rack
which holds the equipment. Heavier things move slower. If you
can get the motion slow enough, it won't cause sonic or tracking
problems.

Another solution is to add rubber or elastomer (Sorbothane)
cushions under the CD player or turntable. This might make it
better, but might also make it worse. Experiment.

A third solution is to increase the coupling between the rack
and the floor using spikes, which concentrate the weight on
a very small area. Another way to increase the coupling between
the rack and the floor is to use a plastic adhesive like HoldIt,
sold under the UHU trade name in office supply stores.

9.11 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) http://www.adcom.com
Audio by Van Alstine
Audio Research http://www.audioresearch.com
B & K http://www.bkcomp.com
California Audio Labs (CAL) http://www.calaudio.com/
Carver (some made in Japan)
Jeff Rowland http://www.jeffrowland.com
Krell http://www.pcnet.com/~krell
Mark Levinson http://www.madrigal.com/MLHP5.htm
McCormack
McIntosh http://www.mcintoshlabs.com
Proceed http://http://www.madrigal.com/PROHP2.htm
PS Audio http://www.psaudio.com
Spectral http://www.spectralinc.com
Sumo (Power amps, preamps, CD transports, D/As)
Wadia http://www.wadia.com/index.html

9.11.1 Any information on equipment made in other countries?
Thanks to Stephane Tsacas, we know:

Australia:
Krix Loudspeakers http://www.krix.com.au
Metaxas http://www.metaxas.com

Canada:
| Bryston http://www.bryston.ca
Coincident http://www.coincidentspeaker.com
Energy Speakers http://www.energy-speakers.com
Newform http://www.barint.on.ca/newform
Paradigm http://www.paradigm.ca
Psb Speakers http://www.psbspeakers.com
Sonic Frontiers http://www.sonicfrontiers.com
Waveform http://www.waveform.ca

Czech Republic:
KR Enterprise http://www.kr-enterprise.com

Denmark:
Bang & Olufsen http://www.bang-olufsen.com
Bow Technologies http://www.bowtechnologies.com
Bruel & Kjaer http://www.bkhome.com
SEK Acoustics http://www.adpointer.net/sekacoustics

France:
Audax http://www.audax.com
Audio Aero http://www.audioaero.com
Audioreference http://www.audioreference.com
Cabasse http://www.cabasse.com
Confluence http://www.a-t.fr/confluence
J-M Reynaud http://www.charente-fr.com/jm-reynaud
Kora http://www.kora.net/index.html
JM Lab http://www.focal.tm.fr
Triangle http://www.triangle-fr.com
Verdier
YBA http://www.phlox-electronique.fr

Germany:
Lehmann audio http://www.lehmannaudio.de
Steinmusic http://www.steinmusic.de

Italy:
Audio Analog http://www.hi-fi-forum.com/audio_analogue.htm
Pathos http://www.hi-fi-forum.com/pathos.htm

Korea:
Pulsus http://www.pulsustech.com

Netherlands:
Final http://www.hi-fi-forum.com/final.htm
Philips http://www.philips.com

New Zealand:
Perreaux http://www.perreaux.com
Plinius http://www.pliniusaudio.com

Norvegia/Norway:
Electrocompaniet http://www.electrocompaniet.no
Tandberg http://home.sol.no/~johandor

Switzerland:
Nagra http://www.nagra.com
Goldmund http://www.goldmund.com
Revox http://www.revox.ch
Lenco
AMT

UK:
Audio Note http://www.audionote.co.uk
Cambridge Audio http://www.cambridgeaudio.com
Newtonia http://www.newtonia1.freeserve.co.uk
Quad http://www.quad-hifi.co.uk

9.12 Should I buy "xxx"? Which is better: "yyy" or "zzz"?
We can provide facts and opinions (and you get to decide which
is which :-), but we can't recommend if, or which way, you
should jump, because we don't know what your priorities are.
(That won't stop us from trying, though!) For example, if you
are considering a used item at a low price vs. a new one at a
higher price, one of us might say "go for the new one because
of the warranty", when another would say that you can fix it
yourself if it breaks. They're both right.

This also applies to speakers. One may have very good, flat
bass, but only go so low, where the other may go lower, but
have less flat frequency response. Which is better? Depends
on the buyer. Good speakers are carefully designed to
achieve a balance of performance that matches the priorities
of the designer. Some designers put much of their budget into
appearance. Some designers put their budget into very high
efficiency. Others strive for the smallest box which can
deliver an acceptable low frequency performance. Do you
really want people on the network making that decision for you?

9.13 What is Surround Sound? Pro Logic?
In an effort to make movie soundtracks more dramatic and
engaging, Dolby Labs created a signal encoding which encodes
more than just two channels of audio onto the stereo signal.
Many popular receivers and home-theater systems include the
required circuitry to decode these signals. These components
are referred to as Pro Logic, Dolby Pro Logic, or Surround
Sound components. Very few audio recordings contain this
encoding, but it is very common with movie soundtracks and
some network TV programs.

Best Surround Sound reproduction requires five separate
speaker systems, but some improvement is claimed from a
surround sound receiver and three speakers over two speakers.
In its best implementation, surround sound will give a fuller
sense of being in the middle of the action. The quality of the
image is a function of the recording, the broadcast quality,
and the choice of reproduction components.

9.14 What do they mean when they say "It sounds warm?"
There are many subjective terms used to describe slight
differences in frequency response, distortion, noise, etc.
Thanks to Bruce Bartlett and Pro Audio Review, we present this
Sound Quality Glossary. This glossary puts a meaning behind
many different, common terms. There is no guaranty that people
mean the same thing when they use these terms. However, these
definitions give insight into why a system sounds the way it
does and may also help bridge the communications gap.

Airy: Spacious. Open. Instruments sound like they are
surrounded by a large reflective space full of air. Good
reproduction of high-frequency reflections. High-frequency
response extends to 15 or 20 kHz.

Bassy: Emphasized low frequencies below about 200 Hz.

Blanketed: Weak highs, as if a blanket were put over the
speakers.

Bloated: Excessive mid-bass around 250 Hz. Poorly damped low
frequencies, low-frequency resonances. See tubby.

Blurred: Poor transient response. Vague stereo imaging, not
focused.

Boomy: Excessive bass around 125 Hz. Poorly damped low
frequencies or low-frequency resonances.

Boxy: Having resonances as if the music were enclosed in a
box. Sometimes an emphasis around 250 to 500 Hz.

Breathy: Audible breath sounds in woodwinds and reeds such as
flute or sax. Good response in the upper-mids or highs.

Bright: High-frequency emphasis. Harmonics are strong relative
to fundamentals.

Chesty: The vocalist sounds like their chest is too big. A bump
in the low-frequency response around 125 to 250 Hz.

Clear: See Transparent.

Colored: Having timbres that are not true to life. Non-flat
response, peaks or dips.

Crisp: Extended high-frequency response, especially with
cymbals.

Dark: Opposite of bright. Weak high frequencies.

Delicate: High frequencies extending to 15 or 20 kHz without
peaks.

Depth: A sense of distance (near to far) of different
instruments.

Detailed: Easy to hear tiny details in the music; articulate.
Adequate high-frequency response, sharp transient response.

Dull: See dark.

Edgy: Too much high frequencies. Trebly. Harmonics are too
strong relative to the fundamentals. Distorted, having unwanted
harmonics that add an edge or raspiness.

Fat: See Full and Warm. Or, spatially diffuse - a sound is
panned to one channel, delayed, and then the delayed sound is
panned to the other channel. Or, slightly distorted with analog
tape distortion or tube distortion.

Full: Strong fundamentals relative to harmonics. Good
low-frequency response, not necessarily extended, but with
adequate level around 100 to 300 Hz. Male voices are full
around 125 Hz; female voices and violins are full around 250
Hz; sax is full around 250 to 400 Hz. Opposite of thin.

Gentle: Opposite of edgy. The harmonics - highs and upper mids
- are not exaggerated, or may even be weak.

Grainy: The music sounds like it is segmented into little
grains, rather than flowing in one continuous piece. Not liquid
or fluid. Suffering from harmonic or I.M. distortion. Some
early A/D converters sounded grainy, as do current ones of
inferior design. Powdery is finer than grainy.

Grungy: Lots of harmonic or I.M. distortion.

Hard: Too much upper midrange, usually around 3 kHz. Or, good
transient response, as if the sound is hitting you hard.

Harsh: Too much upper midrange. Peaks in the frequency response
between 2 and 6 kHz. Or, excessive phase shift in a digital
recorder's lowpass filter.

Honky: Like cupping your hands around your mouth. A bump in the
response around 500 to 700 Hz.

Mellow: Reduced high frequencies, not edgy.

Muddy: Not clear. Weak harmonics, smeared time response, I.M.
distortion.

Muffled: Sounds like it is covered with a blanket. Weak highs
or weak upper mids.

Nasal: Honky, a bump in the response around 600 Hz.

Piercing: Strident, hard on the ears, screechy. Having sharp,
narrow peaks in the response around 3 to 10 kHz.

Presence: A sense that the instrument in present in the
listening room. Synonyms are edge, punch, detail, closeness and
clarity. Adequate or emphasized response around 5 kHz for most
instruments, or around 2 to 5 kHz for kick drum and bass.

Puffy: A bump in the response around 500 Hz.

Punchy: Good reproduction of dynamics. Good transient response,
with strong impact. Sometimes a bump around 5 kHz or 200 Hz.

Rich: See Full. Also, having euphonic distortion made of
even-order harmonics.

Round: High-frequency rolloff or dip. Not edgy.

Sibilant. "Essy" Exaggerated "s" and "sh" sounds in singing,
caused by a rise in the response around 6 to 10 kHz.

Sizzly: See Sibilant. Also, too much highs on cymbals.

Smeared: Lacking detail. Poor transient response, too much
leakage between microphones. Poorly focused images.

Smooth: Easy on the ears, not harsh. Flat frequency response,
especially in the midrange. Lack of peaks and dips in the
response.

Spacious: Conveying a sense of space, ambiance, or room around
the instruments. Stereo reverb. Early reflections.

Steely: Emphasized upper mids around 3 to 6 kHz. Peaky, nonflat
high-frequency response. See Harsh, Edgy.

Strident: See Harsh, Edgy.

Sweet: Not strident or piercing. Delicate. Flat high-frequency
response, low distortion. Lack of peaks in the response. Highs
are extended to 15 or 20 kHz, but they are not bumped up. Often
used when referring to cymbals, percussion, strings, and
sibilant sounds.

Thin: Fundamentals are weak relative to harmonics.

Tight: Good low-frequency transient response and detail.

Tinny, Telephone-like: Narrowband, weak lows, peaky mids. The
music sounds like it is coming through a telephone or tin can.

Transparent: Easy to hear into the music, detailed, clear, not
muddy. Wide flat frequency response, sharp time response, very
low distortion and noise.

Tubby: Having low-frequency resonances as if you're singing in
a bathtub. See bloated.

Veiled: Like a silk veil is over the speakers. Slight noise or
distortion or slightly weak high frequencies. Not transparent.

Warm: Good bass, adequate low frequencies, adequate
fundamentals relative to harmonics. Not thin. Also excessive
bass or midbass. Also, pleasantly spacious, with adequate
reverberation at low frequencies. Also see Rich, Round. Warm
highs means sweet highs.

Weighty: Good low-frequency response below about 50 Hz.
Suggesting an object of great weight or power, like a diesel
locomotive.

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.

--
Bob Neidorff; Texas Instruments | Internet: neidorff@ti.com
50 Phillippe Cote St | Voice : (US) 603-222-8541
Manchester, NH 03101 USA

Note: Texas Instruments has openings for Analog and Mixed
Signal Design Engineers in Manchester, New Hampshire. If
interested, please send resume in confidence to address above.