Info-High-Audio
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Volume 19 Number 1 Friday, January 15, 1993
Today's Topics
--------------
Re: Technical Questions about ESLs
Re: Benefits of high-current design?
HDCD compatabilty
mail order
INFO WANTED (Dynaco, Sonic Frontier, McIntosh)
Re: recording quality
Re: BRYSTON
Bipolar Speakers: Positioning???
Electronics for 802s
Re: HDCD
STAX Sigma headphones
connections
Mark Levinson Digital Processor
Re: What became of Threshold?
Blue Laser
Re: adcom gcd-575 skipping
Re: Sota and HDCD
FOR SALE: Interconnects
question about speaker wire and gauges
----------------------------------------------------------------------
From: widener!rnd.stern.nyu.edu!sbhattac@cmcl2.NYU.EDU (Shankar Bhattacharyya)
Subject: Re: Technical Questions about ESLs
Date: 14 Jan 93 13:43:45 GMT
In article <1iuncaINN9hd@uwm.edu> Sheldon__Stokes@qmgate.arc.nasa.gov (Sheldon Stokes) writes:
>1) Is the membrane that is electrostatically charged semi-condustive, or is it
>just a piece of mylar? I am assuming that there is a conductiv4e strip at the
>top and bottom that a DC power supply is attached to. What sort of potential
>is applied to this membrane (the Acustat 1+1 use a plug in transformer like a
>portable cassette deck would use; this leads me to believe that the potential
>is small)? Is one side grounded and the other side held at a raised potential?
First, I disclaim any claim to expertise. I just claim enthusiasm. Also, I
apologize in advance for any odd context. I have copied in a considerable
amount of stuff from a long, earlier, post and I may not have edited
things down properly.
In modern esl's the membrane tends to be raised to some voltage above the
mean voltage between the two plates. So the plates are driven by a
centre-tapped transformer, with the centre tap grounded, and the membrane
bias is applied between ground and the membrane. Voltages from somewhat over
1 kV on up get used. A photocopier power supply serves adequately, provided
you can scale the voltage down quite a bit. They tend to provide 7 kV on
up, in my limited sample, and you need a good bit less than that. 3 kV
should do for almost any design one is likely to build at home.
That generalization may reflect limited experience on my part, though. I
have only built one esl (yes, that's exactly half a pair) since I already
had a pair of old Quads, but I learned a little in the process.
>2) The plates on each side of the membrane have a high voltage signal applied
>to them via a step up transformer. What is the winding ratio of that
>transformer usually?
That turns ratio varies from about 50:1 to about 100:1 in the esl's of
which I know. One of the Quads uses 100:1, if I remember correctly. There
are a few transformers out there with a turns ratio of about 50:1,
available to the builder. Sanders recommends the Triad S-142A for his
design. Turns ratios above that could be hard for the home builder to achieve.
> ........... I
>understand the principal that they work under, but am not sure of the values.
You should read the papers by Peter Walker, in the 1955 issues of Wireless
World, if you have not read them already. They will not tell you about
quantities, unless you know a lot more electrical engineering than I do
(knowing more than I do is easy, by the way), but those papers are the
classics on the subject. It is surprising how much the guy had thought about.
I have some prejudices as to how one should go about building esl's.
First work out the essentials of your design.
Then slap a panel together, without regard to sound quality. This is
a cheap experiment, and teaches you a lot about the mechanics of
construction, and something about design choices, and it dramatically
improves your subsequent decision-making. There are all sorts of small
issues which you will not have anticipated. If you are really thorough
about a gedanken experiment in construction you may be able to foresee most
of the problems, but this is cheap enough that I think it is best to go
ahead and just build one. Besides, a gedanken experiment will not tell you
much about the physical complexity of many step. You often have to do the
manipulations to learn that. Good gedanken experiments are every bit as
hard as real experiments, though cheaper. Of course, you can build a sort
of scale model as an initial pass, and you should be able to learn almost
as much from that as from a full-scale job.
This can be done in a weekend once you have the materials.
The rest of this post is stuff I have posted before, but it doesn't hurt
to point people to the published sources, so what the hell.
Rick Karlquist and I exchanged a few messages as to literature quite some
time ago, and this list contains stuff I got from him, as well as
references I already had.
The 1955 Walker papers are:
Walker, Peter J., Wide Range Electrostatic Loudspeakers
A series of three papers, in Wireless World, 1955
1. Principles of Design for Operation at Low as Well as High
Frequencies with Negligible Distortion, Wireless World,
May 1955, p 208.
2. Problems of Air Loading: Different Requirements of Moving-coil
and Electrostatic Drive Units,
June 1955, page 265.
3. Complete Systems: Loudspeaker/Room Relationships,
August 1955, p 381.
And a couple of corrections in July 1955, p 346.
These papers are an absolute tour de force. You must read this if
you plan to build esl's, indeed if you have any interest in esl's
at all. The man thought of everything. It is startling how
little has been contributed since then. Peter Walker is God.
Be careful to ensure that you get everything. They tend to do the
"continued on page such and such" bit.
Also:
Borwick, J. (editor), Loudspeaker and Headphone Handbook, Butterworths, 1988
Informative chapter on esl's. The book is about $100, but most
engineering libraries should have it. It has more theory than any
other secondary/tertiary source I have seen, but little how-to
information.
The ESL chapter is by Baxandall.
It's a pretty good book, and covers lots of good stuff other than
esl's.
Newman, R.J., Dipole Radiator Systems, J. Audio Eng. Society,
vol. 28, #1/2, p35, 1980.
This paper says nothing about esl's specifically, but it is of
general interest to esl builders. It lets you understand bass
response better.
Construction articles:
Hermeyer, David, An Electrostatic Speaker System,
The Audio Amateur 1972, #s 3 & 4
I have not seen this. I suspect one can get along without it.
Hermeyer included a massive direct-drive tube amp, by the way,
that people have described as great. I have no opinion on it.
Sanders, Roger R.:
The Audio Amateur, 1975 #4, and 1976 #1.
This was Sanders's first published design, and is faintly
interesting, but I did not find it instructive. However, it has
information on direct-drive tube amps and such, that might
interest you. These articles seem derived from Hermeyer's
work. Sanders had not yet become the full-blown Sanders.
An Electrostatic Speaker System, Speaker Builder 1980, #s 2, 3, 4
Part 1: 1980, #2, p 20 (general issues)
Part 2: 1980, #3, p 20 (panel construction)
Part 3: 1980, #4, p 26 (TL woofers, system integration)
These are very instructive articles. Sanders despises technical
types, and his style can drive one up the wall, but he knows a
lot about the practical issues of esl design and construction.
These articles pursue his earlier designs to a quite
respectable state.
You do have to decide how seriously you will take his opinions,
since he does not just have opinions. He has the Truth (tm),
and brooks no differences of opinion. In particular, he
absolutely despises any technical quibbles from what he calls
"technofreaks". That means anyone who thinks a differential
equation is a useful thing.
In any case, if you want to build esl's, you have to read these
articles.
Related letters appeared in subsequent issues of Speaker Builder,
in 1980, #s 3 &4, 1981 #1, 1982 #4, 1983 #s 3 & 4, 1984 #3.
Some of it is discussion, some argument, and so on.
A Compact Integrated Electrostatic/Transmission Line,
Speaker Builder, 1990, 3 articles, #1, p 30, #2, p 36, #3, p 38.
I found these less instructive. The information is useful, but
not groundbreakingly so, while the 1980 articles are. These
1990 articles have too much stuff in them, all in parallel.
Three different construction techniques are described. A much
hyped "beam-splitter" technique is described, but I don't get
it.
To get the full benefit of this series I think you have to have
read his 1980 series.
A correction appeared in Speaker Builder, #4, 1990, p 3
In his 1990 articles he recommends the Triad S-142A transformer.
Wagner: Electrostatic Loudspeaker Design and Construction,
Tab Books Inc., Blue Ridge Summit, PA, 1987,
ISBN 0-8306-0832-X (hardcover), 0-8306-2832-0 (paperback)
The design described in it is vastly over-elaborate. The book has
useful tables and so on, many of which are formulated in ways that
make you work to use them.
There is potentially useful stuff on directivity and such.
The book has reprints of some early esl papers, including the
Walker papers from 1955, but cheerfully neglects to provide any
references, not even the references which were in the original
papers. Hell, he does not even tell you exactly where the papers
themselves came from. It is a very frustrating book. Lots of
information, enough so that you would expect it to be written
more or less like a technical book, and then he skips stuff
you would expect to see. I'm not thrilled about the organization.
Wagner coats the diaphragm with Ivory soap, I think, and that is
probably not a great long-term design choice, but graphite would
be easy to use instead, and would be a much more conventional
choice.
Lang, David, Amber: A Sheathed Conductor ESL, Speaker Builder #6, p18, 1988
Interesting construction technique, based on the Acoustat
technique of using insulated wire for stators. It would probably
perform quite well, but I suspect the efficiency would be rather
low. Almost no performance informance is provided.
There were follow-up letters in Speaker Builder 1988 # 1, and
a correction in 1989 #2, both from Lang.
Lang also provides a list of 18 patents, but the patents are of
limited interest to all but the most deadly serious builders.
I collected them all, and while I am reluctant to say that
not knowing what was in them would have been better, I sure
as hell haven't learnt anything I can use.
The Hermeyer and Sanders work is reproduced in "Audio Amateur Loudspeaker
Projects", Marshall-Jones, 1985. I know the 1975 Sanders stuff is in there.
I don't know about his 1980 articles, and, of course, the 1990 articles are
more recent than the book. The book is available from Audio Amateur
Publications.
Wagner's book was reviewed in Speaker Builder, in #4, 1982, with follow-ups
and letters in 1988 #2 & #3. The review is not particularly objective. It's
by Sanders, and I think he is miffed that Wagner did not credit his work.
That annoyance is justified, since it is irresponsible to write about esl
construction and not mention Sanders, but the book is better than Sanders
suggests. The paperback may be out of print. I don't know for sure.
Speaker Builder 1988, #5 has some interesting information on plate
insulation, and other related and unrelated subjects, with comments from
Sanders and Wagner in response to a letter. Well worth a look.
Speaker Builder and The Audio Amateur are published by :
Audio Amateur Publications
PO Box 576
Peterborough, NH 03458
(603) 924-9464 (9-4, M-F)
A subscription to Speaker Builder is $25 a year for six issues. Subscribers
can order single back issues., but non-subscribers must order a whole
year's worth of issues. That's how I understand it, anyway.
If you are not familiar with Wireless World, it was an entirely respectable
journal. I don't know if it is still around. A good engineering library
should have it.
JAES, of course, is easily accessible.
By the way, if there is a patent on the Quad ESL-63, I would dearly love
to get a copy. Just a US or UK patent number would be nice, too.
A warning:
The voltages in esl's are dangerous. Make sure you know how to deal with a
few kilovolts. You could do some serious damage to yourself. If you know
what you are doing it is no problem. If you don't, you could get dead. That
is a bit of an extreme result, but it is not impossible.
Also, even just in terms of esl functioning, you really need to be more
careful about the polarizing voltage than Sanders leads you to believe.
My inclination is to use wider diaphragm to stator spacing than he says,
and to use higher polarizing voltage, but if you don't isolate the assembly,
you can get odd discharges. I had a steady orange discharge into the floor
till I raised the panel and took steps to isolate it. A friend who does
plasma physics helped me deal with that sort of thing. Conductivity
along wood surfaces is pretty high, for instance. And, at high voltages,
discharges can occur around corners and so on. The voltages inside esl's
are really not all that high, as high voltages go, even though they are
sufficient to be dangerous. My plasma physicist friend dismisses 50 kV as
a medium voltage, nothing to get excited about, but he deals with about
200 kV every day, and knows how to deal with these things.
Rick Karlquist reports that he has had an esl he was building burst into
flame.
The high voltage supplies are really quite easy to build. You do need
access to a high value resistor of significant wattage, or you risk blowing
the resistor. This resistor goes between the supply and the diaphragm,
and maintains constant charge on the diaphragm. I don't really know that
it has to be high wattage, but it concerns me that at early stages of
charging the diaphragm, several kV gets dropped across the resistor.
On parts for esl's :
HV supplies are available from Herbach and Rademann in Baltimore, for about
$15-20 each. They are a mail-order surplus place. Plenty of other places
will have suitable supplies.
The Triad S-142A transformer is available from :
Antique Electronic Supply
6221 S. Maple Avenue
Tempe, AZ 85283
The telephone number is 602-820-5411.
I believe the TRW/UTC LS-10 and LS-20 transformers would be terrific, but
they are very expensive. At long intervals they show up on the surplus
market. I'll pick up a pair if I can. If you have a pair, and are willing
to part with them, let's talk.
Sanders supplies 1/2 mil mylar.
Finally, Martin-Logan is a quite friendly establishment. they won't sell
you parts, but they are quite willing to talk about esl's in general
terms. I'm hoping to clone a Quest some day, with a pass at the Sequel II
as a practice run.
- Shankar
------------------------------
From: widener!rnd.stern.nyu.edu!sbhattac@cmcl2.NYU.EDU (Shankar Bhattacharyya)
Subject: Re: Benefits of high-current design?
Date: 14 Jan 93 14:40:12 GMT
In article <1j17qkINNiq8@uwm.edu> gfl@herahera.cc.bellcore.com (lenahan,grant f) writes:
About Mosfet amps:
>Bzzzzzzt. They don't need thermal compensation. It has little to
>do with current limiting / protection.
Is that really true? They don't need to be protected against thermal
runaway, but depending on the bias, compensation against the dependence of
characteristics on temperature presumably has to be attended to.
I've built the Borbely DC-100 (with lots of help from Henry Pasternack,
Seth Bradley, and Len Moskowitz), and Borbely chooses a bias such that it
minimizes temperature dependence, so it is at least a design criterion.
For the Hitachi Mosfets so widely used, a 100 ma bias appears to minimize
temperature drift.
If I am over-interpreting Grant's post, or misinterpreting it, my apologies.
Given my level of understanding of electronics, it would be easy for me to
do either.
- Shankar
------------------------------
Date: Thu, 14 Jan 93 11:57:23 EST
From: jas@proteon.com (John A. Shriver)
Subject: HDCD compatabilty
HDCD CD's should be completely compatible with any existing CD player,
transport, or D/A. There is no change in the low-level format, it all
starts with a Sony 1630 U-Matic 3/4" video-tape master, just like any
other CD.
There would be zero market for a non-compatible CD format. (A shame,
since using 16 bit floating point would blow away the current
brain-dead linear format!)
All of the information on a CD comes out the SPDIF interface,
including every last subcode bit, so wherever they may be stuffing
bits, they will be available to an external D/A convertor.
Come think of my previous comments that they might have an extra track
on the CD, I now realize that that is totally improbable. The D/A
can't send any commands back over the SPDIF interface, so their
technique is clearly based on a novel encoding technique. My guess is
still correlated pseudo-random dither. Hmm, maybe they play some
games with subsonic signals, but I'm just grasping at straws.
Obviously, one needs a HDCD D/A to hear the full benefit of HDCD
encoding. Only some of the benefit is available on a standard D/A.
It sure sounds like another reason to wait before spending a lot on CD
equipment. Or at least ask if the expensive DAC you're buying will be
reasonably upgradable to HDCD decoding.
------------------------------
From: gvanmoor@nrao.edu (Gustaaf Van Moorsel,,,)
Subject: mail order
Date: Thu, 14 Jan 93 18:03:56 GMT
I would appreciate some comments on recommended mail order places for buying
medium/high end audio products. Or should I pay more and support my local
audio store?
Gustaaf van Moorsel
------------------------------
From: yk7m@uvacs.cs.Virginia.EDU (Young-Kuk Kim)
Subject: INFO WANTED (Dynaco, Sonic Frontier, McIntosh)
Date: Thu, 14 Jan 1993 18:12:55 GMT
Hi, Audiophiles
I would like to get some information on the following equipments:
1. Dynaco Stereo 70 II amp KIT (not complete product)
2. Sonic Frontier Amp Kit (EL34)
3. McIntosh MC275 Amp
- How and where can I get them?
- How much do they cost?
I would really appreciate your help.
-- Young-kuk Kim
------------------------------
From: Chris Johnson <chrisj@emx.cc.utexas.edu>
Subject: Re: recording quality
Date: 14 Jan 1993 18:35:01 GMT
In article <1j3sb4INNskl@uwm.edu> Rudolf Daniel Riet, rdr4972@u.CC.UTAH.EDU
writes:
>_Dark Side Of The Moon_
>
> The MFSL disc is still better, probably due to its lower mastering
> volume level. The sound, in some parts, gets compressed in the _Shine
> On_ version. Otherwise, it's markedly improved from either Capitol
> version, with better sound effects and vocals. Also, it seems that
> Dave's wish to "clean up the drums" has been fulfilled, somewhat, as
> the drums do sound a bit more clear on this version.
For whatever it's worth, I have to disagree about the MFSL disc. I have
all three versions of Dark Side of the Moon and to my ears it ranks an
annoying and expensive third to the Capitol and Shine On versions.
(I also find the MFSL disc absurdly over-packaged, but that's another
matter.)
The Capitol release, of course, is nothing special and doesn't sound
particularly wonderful. My low opinion of the MFSL disc stems from my
feeling that the bass was over amplified and muddied, and that vocals,
especially the snippets of speech and conversations lurking in the
background of several tracks, were made muddled and more difficult to
understand. Note that these judgements are relative to the quality of
the Capitol disc, which was all I had to compare the MFSL disk with at
the time I bought it.
The version included in the Shine On box set is, for my money, the best
version. It's strikingly clear, clean and balanced - nothing sounds over
amplified or muddied - and all-in-all it's just a pleasure to listen to.
Highly recommended.
Of course, everyone gets their own opinion and this is just my $.02 worth;
your mileage may vary.
Chris Johnson
Internet: chrisj@emx.cc.utexas.edu
UUCP: {husc6|uunet}!cs.utexas.edu!ut-emx!chrisj
BITNET: chrisj@utxvm.bitnet
CompuServe: >INTERNET:chrisj@emx.cc.utexas.edu
AppleLink: chrisj@emx.cc.utexas.edu@internet#
------------------------------
From: dw@csri.toronto.edu (Dave Wortman)
Subject: Re: BRYSTON
Date: Thu, 14 Jan 1993 14:24:49 -0500
Bryston global headquarters is like that too. Some local electrical
storms managed to fry the thermal overload in my 1983 vintage 1B preamp.
I took it out to Bryston (funky little office/factory in a nondescript
industrial park in NW Toronto). The receptionist saw me come in and
walked me through their manufacturing operation (really LONG benches
with 3Bs and 4Bs being burned in) to the guy in back who actually
does the servicing. We had a long chat about what might be wrong and
how he was going to fix it and when. (He had a very small repair queue
for a company the size of Bryston). With luck, repair time (under
warantee of course) will be about a week (I told him it wasn't urgent,
or he would have done it sooner).
I've been extremely pleased with my Bryston gear, this is the first
time I've actually needed anything repaired.
P.S. The Canadian Broadcasting Corp (Canada's national radio/tv network)
appears to have adapted Bryston as their default amp and preamp.
I toured their new broadcasting centre recently and they had more Brystons
than I could count.
------------------------------
Date: Thu, 14 Jan 1993 15:02:18 -0500 (EST)
From: Shiv Swarup Pathak <sp3u+@andrew.cmu.edu>
Subject: Bipolar Speakers: Positioning???
Recently, I bought a pair of Definitive Technology BP-10 bipolar
loudspeakers. I live in a medium-sized dorm room (12'x15') with one
wooden wall (the shorter wall, composed to drawers and closets). The
other walls are plaster (the one opposite the closets/drawers has large
windows. Due to limitations I have to keep the speakers on the side
with the wooden closets/drawers. Does anyone have any recommendatiosn
on how to positions them. I have already experimented but I'm looking
for other opinions. Thanks in advance.
-SHiv
------------------------------
From: trent@sag4.ssl.berkeley.edu (Trent Tucker)
Subject: Electronics for 802s
Date: 14 Jan 1993 21:09:23 GMT
A couple of years ago, I decided to upgrade my system. I started with
speakers, and found a great deal on a pair of Series 2 B&W 802s.
Unfortunately, they consumed nearly all of my budget. All that I
could afford in the way of an amplifier was a Parasound HCA 800. A
very nice amp for the price ($400), but not quite and good match for
the 802s. Now that my finances have recovered, I'm thinking about an
upgrade. Since the Parasound has volume controls and most bigger amps
don't , I'll also have to buy a preamp at this time. All of my current
listening is from CD.
I'm thinking in terms of spending ~$2000 on the amp, $1000-$1500 on
the preamp.
So, what do other 802 owners drive their speakers with. Which electronics
are a good match with them? Recently, the McCormack DNA-1 has gotten
good press. Has anyone heard it matched with 802s?
Any suggestions in this price range?
I appreciate any wisdon that you can offer.
Thank You.
Trent
------------------------------
From: Frank.S.Grassia@williams.edu (Frank S. Grassia)
Subject: Re: HDCD
Date: 14 Jan 93 16:51:30
CD's recorded in HDCD will play in a standard transport and D/A, and still
sound better than conventional CD's. The HDCD decoder is just an extra
chip built in to the D/A, so the transport should still be usable for
getting the full benefit of HDCD encoding and decoding.
Frank
--
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!! Frank S. Grassia !! Living vicariously !!
!! 93fsg@cs.williams.edu !! through the models and images I create. !!
!! The Graphics Cowboy !! (((((((((((*))))))))))) !!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
------------------------------
From: peterh@uxa.cso.uiuc.edu (huang peter suway)
Subject: STAX Sigma headphones
Date: Thu, 14 Jan 1993 22:06:44 GMT
I presently own a pair of STAX SR-Lambda Signature earspeakers with the
SRM-T1 amp. I have not demoed the SR-Sigma Pro earpeakers and am
wondering how they sound. They cost about $1000 a pair. I was wondering
if anyone has listened to them and what they think of them. How do they
compare to the Lambda Signatures?
I was also wondering about the STAX diffuse field equalizers. If you are
familiar with them, could you tell me your opinions on them?
------------------------------
From: peterh@uxa.cso.uiuc.edu (huang peter suway)
Subject: connections
Date: Thu, 14 Jan 1993 22:49:38 GMT
I was wondering if high-end, expensive interconnects and speaker cables
from companies such as Audioquest, Straightwire, and Tara Labs are worth
the extra money. Do they really improve the sound noticeably? If you
have any experience with them, could you tell me your opinions concerning
them?
------------------------------
From: peterh@uxa.cso.uiuc.edu (huang peter suway)
Subject: Mark Levinson Digital Processor
Date: Thu, 14 Jan 1993 23:13:13 GMT
I was wondering what the function of a digital processor is and how it is
implemented into an audio system. Is anyone familiar with the Mark
Levinson No. 30 digital processor? Is it worth anything near its price
of $13,950?
------------------------------
From: apctrc!znpt01@uunet.UU.NET (Norman P. Tracy)
Subject: Re: What became of Threshold?
Date: Thu, 14 Jan 1993 22:08:23 GMT
In article <1iuna3INN9go@uwm.edu>, D.Robert.Spexet@math.lsa.umich.edu (D. Robert Spexet II) writes:
> I notice that Threshold (Nelson Pass' company, makers of the Statis
> technology that is used in some amps) no longer seems to exist.
>
> What ever became of this company?
>
> --
> D. Robert Spexet II, N0OKR Internet: spexet@umich.edu, dspexet@attmail.com
Seems to alive and kicking, contrary to wreck.audio.high-end rumors.
I just called them at:
Threshold
7325 Roseville Rd.
Sacramento CA 95842
916-348-0600 voice
916-348-0678 fax
The above from a full page ad in Jan. Stereophile announcing a new line of
balanced pre-amps and IGBT amps.
I guess this rumor started because Nelson Pass has left Threshold. His new
company is:
Pass Laboratories
21555 Limestone Way
Foresthill CA 95631
916-367-3690 voice
916-367-2193 fax.
Bucking the trend towards balanced everything Nelson's only product is a
mono 75 watt class-A amp with a SINGLE ENDED output stage! Talk about your
basic room heater. Only $7000 pair, right now the entire production is going
to Germany and the orient. Should help the balance of trade deficit. It
seems Threshold got to be too much of a job and not enough fun so Pass is
keeping his new company small and personal.
If like me you are a long time fan of Nelson Pass and his design's get the
4/92 and 1/93(not yet published) issues of The Audio Amateur magazine. In it
Nelson and his co-author Norman Thagard (whose day job is Space Shuttle Pilot)
go into wonderous detail on an amp project called A75. A conservative 75 wpc
("only" 24 ea. 250 watt output MOS-FETs per-channel) in class-A mode it should
swing 100s of watts in A/B mode. Its a great article with complete descriptions
of using FETs and a look into the tradeoffs experienced amp designers make.
Highly recommended as a project (my buddy is buying transistors with out even
waiting for part 2) or a tutorial.
Norman Tracy
--
znpt01@trc.amoco.com
------------------------------
From: Michael George Buening <Michael.G.Buening.1@nd.edu>
Subject: Blue Laser
Date: Fri, 15 Jan 1993 01:05:44 GMT
I was told by someone with some knowledge but not necessarily an audiophile
that Phillips was ready to almost market a blue laser for use in CD players
as well as I suppose eventually in CD-ROM and other optical technology. My
question to you is how would this change the CD technology we use today
which I believe is in the red range. The blue will have a shorter wavelength
but I don't know how that affects the data storage and retrieval on the
compact disc. Will this make for better sound, more music/disc or just
another system that we don't need. Also, this must necessarily mean that
the red laser system and its discs are not compatible. True? Then we have
a whole new battle of which system is best and which company can market their
product most effectively. Any and all information in this regard is greatly
appreciated.
Mike
--
| Michael Buening |
| mike@nowaksg.chem.nd.edu |
------------------------------
From: randyd@csd4.csd.uwm.edu (Randall Elton Ding)
Subject: Re: adcom gcd-575 skipping
Date: 15 Jan 1993 01:09:22 GMT
In article <1j3sbaINNskq@uwm.edu> David Dennis <dpd@leland.stanford.edu> writes:
>I own an Adcom GCD-575 Cd player.
>
>However. . . the player does skip rather easily. Does anyone have any
>experience with this or possible solutions? I have put Audioquest
>sorbothane feet underneath the player and this seems to ameliorate the
>problem somewhat, although it does not eliminate it.
>
>solutions need to be cheap, preferably under $150.
>
I had to move my two subwoofers farther away from my GCD-575 to stop my
CD player from skipping on deep bass notes. I have not noticed, however,
that this cd player skips more than others in the same price range. I
would expect any cd player to skip if you play your music as loud as
I do. I routinely need to put things back on the walls after playing
the 1812.
Possibly, if you put speaker spikes on the bottom of your rack,
you may stop some of the wiggle. Remember, you need to press the
speaker spikes thru the carpet and down into the hard floor.
If that doesn't do the trick, then try some 4x4 shock absorbers. :-)
Randy
------------------------------
Date: Thu, 14 Jan 1993 19:20 PDT
From: HENSONSA@MARCUS.WHITMAN.EDU
Subject: Re: Sota and HDCD
If you are looking at Sota, you might also want to look at VPI. Both are
highly regarded by the audio press (i have heard both mid-level decks and
thought the sound was similar from both--couldn't decide between the two).
Both VPI and Sota offer upgrade paths on their decks--you can buy the lowest
priced table (HW-19 jr or Satellite respectively) and upgrade to the most
expensive (or almost most expensive) tables at little or no additional cost
over what you would pay for the top table--i.e. cost of upgrade is the same as
the cost of the table you are upgrading to, minus the cost of the basic table.
Incidently, in Portland, at a store called the Coffee Shop Trading Post, there
is a Sota Star-Sapphire (old model, pre-vacuum) with a home built "electronic
flywheel" (in addition to the regular power supply) sans arm board, for just
around $400.00. It looked like it was in good condition, and as far as I know,
the old Sotas can be upgraded via the new Sota products (they changed owners in
1990 or 1991). I don't have the number, but you can call information if you
are interested.
As far as I know, HDCD is independent of the transport--it is all in the D/A
converter--so I suppose you could use your Theta Data or Magnavox or Audio
Alchemy or [insert brand name here] transport as before. However, as always,
I could be wrong--it wouldn't be the first time.
-Derek
------------------------------
From: gallian@tellabs.com (Doug Gallian)
Subject: FOR SALE: Interconnects
Date: Thu, 14 Jan 1993 18:52:30 GMT
FOR SALE!!! HIGH-END INTERCONNECTS
2 pairs (MIT 330 PLUS) interconnects:
1 pair is 2 meters long New cost $500.00 Asking $190.00
1 pair is 1 meter long New cost $375.00 Asking $125.00
If interested call Doug at 708-955-3062 days leave message or
call 708-739-0719 evenings leave a message. Or e-mail.
------------------------------
From: hum@cs.concordia.ca (HUM william)
Subject: question about speaker wire and gauges
Date: Fri, 15 Jan 1993 05:23:15 GMT
I've often wondered about this so I thought I'd ask others who know
more about electronics than myself. If I were to bi-wire (not bi-amp)
my speakers with 2 sets of 16 gauge speaker wire, would it be equivalent
to just wiring them with one set of 8 gauge wire? Of course I'm assuming
that other than for the gauge, both sets of wire are equal quality-wise
if that's possible??
Will.
------------------------------
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