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       Volume 20 Number 9                 Friday, March 12, 1993
 
 
Today's Topics
--------------
 
 Opinion Needed: OHM Acoustics FRS-11 Speakers
 Re: Hafler?
 Re: Puzzle with Class A amplifiers
 LP-12 Stock Motor Wanted
 Help- dbx source
 Re: Cambridge
 Business as usual remastered?
 Audio Note: Searching everything beeing sold
 Re: Testing Metal and Mettle
 Re: Puzzle with Class A amplifiers
 Kef 103.4 vs B&W 804
 Op-Amps
 PCM63P
 RE: Adcom Tuner
 FOR SALE: McIntosh Tuner
 where can I find used high end audio?
 Wanted: Kappa-9's and other kappas
 Re: Puzzle with Class A amplifiers
 "Pooge" tips for novice
 International Audio Review
 Need info on Sony TA-F 1090 ES amplifier
 B&W 801 mods, environments
 Re: Low price interconnect & cable
 Opinion about Melos MA110B preamplifier
----------------------------------------------------------------------
 
From: "Binh Q. Tran" <binht@Bonnie.ICS.UCI.EDU>
Subject: Opinion Needed: OHM Acoustics FRS-11 Speakers
Date: 10 Mar 93 21:19:05 GMT

Has anyone ever used the Ohm Acoustics Coherent Line Source speaker the
FRS-11?  I'm having trouble setting it up to my room which is 20' x
20'.  How close should they be to the corners? Also,  has anyone had
trouble producing deep bass from these speakers?

------------------------------
 
From: johnson@hal.com
Subject: Re: Hafler?
Date: 11 Mar 1993 00:03:37 GMT

Hafler stuff are all designed in Arizona and made in Mexico.  Couple of
months ago I bought a Hafler Transnova9300 and I used it to drive a
pair of Accoustat Spectra 1100 ( mushy-mushy ) and later a pair of
Apogee Duetta's ( major power hogs ) and I have come to the same
conclusion:

Very short decay times  in the highs leading to a lacking of
soundstage and air.

But anyway, a good bang for the buck if you get them used or
well-discounted from mail-order houses.

--Johnson Wu
johnson@hal.com 

------------------------------
 
From: MATGBB@LURE.LATROBE.EDU.AU (BYRNES,Graham)
Subject: Re: Puzzle with Class A amplifiers
Date: Wed, 10 Mar 1993 23:37:30 GMT

In <1ni7hcINNbd0@uwm.edu> lipp@mtu.edu writes:

> In article <1nfl7gINNmgv@uwm.edu>, bellcore!ardour.bellcore.com!hsong@uunet.UU.NET (G. Hugh Song) writes:
> > How come do class A amplifiers double their power rating as the load impedance
> > halves?  Low impedance draws more current, assuming that the output signal is
> > the voltage applied to speaker impedance, thus I think that a class A amp
> > with a lower impedance load will reach the current limit sooner and clips 
> > earlier than with higher impedance loads.  However, opposite observations
> > can be found in the brochure of Krell's class-A amplifiers.  For instance,
> > 100 w/ch @ 8 ohm,  and 200 w/ch @ 4 ohms, ...  It is not 
> > just Krells, Kinergetics has such a spec, too.  Also with Forte 4...
> > 
> > What am I missing?   Are they all push-pull class A/B amplifiers with 
> > high biases (and small rail voltages)?   If this is the case, there is no point
> > to have a class A amplifier, right?
> > 
> > 	Thanks.
> > 
> > 	Hugh
> 
> Your asking the wrong question. 

No, I think he is asking precisely the right question. A high bias AB amp
*IS* class A up to the power level where the peak current draw is approx. 
twice the bias current. Above that it is class AB. So the big Krell's,
Thresholds etc specc X watts class A into 8 ohms, 2X watts (no mention of
class A) into 4 ohms, 4X into 2 ohms and so on.

Which is fair enough. Better to have an amp that runs AB on peaks than
one that clips... I think you are confusing class A with single ended
design, in which all the power is class A (but there won't be very much :-)).

Class A operation is defined by the fact that the output devices remain in
their linear region (ie they don't turn off), see the FAQ in rec.audio,
not be a particular topology.

 The correct question is why don't class AB
> amplifiers have twice the power rating at half the load. 
Also a good question, but a different one...

[...]
 In reality, many class-A amplifiers
> are as you said just very highly-biased class-AB amplifiers, with the result
> being that the bias current goes up under full output and lower loads. 
Huh? The current consumption goes up, but the bias current doesn't, since
more of it is being diverted to the speakers. That is why class A amps are 
most efficient at full power...

 The
> truth of this can be seen by inspecting power consumption data for idle and
> full-ouput; the latter is sometimes stated and often measured to be higher;
> I have seen a factor of 2 difference as common.
> 
Which is exactly what you would expect for an amp at the limit of its
class A region.

> The reported benefit of class-A is the belief that since the average amount of
> power drawn via music is small, a class-A amplifier essentially remains in a
> static state.  That is, the sound quality does not change because the power drawn
> to the speakers is insignificant and doesn't disturb the "tuning" of the
> amplifier.
 Well, I've never heard this, but then...
What is the "tuning" of the amp in this context?             
                                                Graham Byrnes

------------------------------
 
From: davidj@rahul.net (David Josephson)
Subject: LP-12 Stock Motor Wanted
Date: Thu, 11 Mar 1993 00:38:51 GMT

If someone has a stock LP12 motor that still has good bearings,
please e-mail me with the asking price... I'd like to replace
mine before the audible rattle starts being loud enough to get
transmitted to the cartridge.

Thanks!
-- 
------------------------------------------------------------------------
Josephson Engineering, San Jose California      MICROPHONES
Tel/ 408-238-6062  Fax/ 408-238-6022            INSTRUMENTATION
------------------------------------------------------------------------

------------------------------
 
From: jmschofi@athena.mit.edu (Jeremy   Schofield)
Subject: Help- dbx source
Date: 11 Mar 1993 00:45:57 GMT

Hi-
I have three questions re dbx gear:
1)who handles this stuff in the US? manuals/schematics etc
2)approx value of dbx CX-3 mkII control amp (preamp w/surr sound)
3) approx cost of dbx Ct-3 mkII tuner anybody know of one on the net>?
Thanks
JMschofi@mit.edu
...line eater foo.. urp!!@#

------------------------------
 
From: law40001@nusunix1.nus.sg (CHENG KWONG WING)
Subject: Re: Cambridge
Date: Thu, 11 Mar 1993 01:47:14 GMT

Just to add on to what Peter said:

The dealer in Singapore is at the basement level of Upper Serangoon
Shopping Centre.  Can't remember the name of the shop though, but they
do occasionally advertise in the Classifieds of the Straits Times.

--
email: law40001@nusunix1.nus.sg or law40001@nusunix3.nus.sg

____________________   .    .   __         . 
\______NCC_1701_____|) .____.--"--"---._____ 
             ||      /-----._________.----/  
     /=======||====/___/       "--"          
   . \==\____________|(-                .   

------------------------------
 
From: Paul Faulstich <pfaulsti@abacus.bates.EDU>
Subject: Business as usual remastered?
Date: Thu, 11 Mar 1993 02:44:08 GMT

I am curious if the album Business as Usual by Men at Work was ever
remastered.  I have the vinyl version, and it has to be the worst mastered
or recorded album I have ever heard.  The tinniness (spelling?) of the
saxaphones and cymbals are grating on my ears.

How do other people feel or know about this?

Paul

--------------------------------------------------------------------
- Paul Faulstich                      Lab Instructor, Physics Dept -
- pfaulsti@abacus.bates.edu            Bates College, Lewiston, ME -
--------------------------------------------------------------------

------------------------------
 
From: schreibe@goofyzdv.uni-mainz.de (Tomas Schreiber-Ringel)
Subject: Audio Note: Searching everything beeing sold
Date: Thu, 11 Mar 1993 11:28:15 GMT

Audio Note: searching

Is there anyone who has old Audio Note material somewhere and does not use it?

If so, please send me a mail I am interested.

tomas schreiber - ringel

------------------------------
 
From: shetline@bbn.com (Kerry Shetline)
Subject: Re: Testing Metal and Mettle
Date: 11 Mar 1993 15:11:51 GMT

In article <1ni7hhINNbd4@uwm.edu>, JCOBBS@auvm.american.edu (James A.
Cobbs) wrote:
>    Twenty five years ago an album was issued that was the first
> classical album to go Gold.  It was "Switched On Bach" and was done
> on a MOOG.  The creator (whose name escapes me) has now come up with
> an updated, CD version done with digital equipment.  It's title is
> "Switched On Bach 2000"  Heard some of it on a local FM station
> yesterday.  Wow.  Did some A-B comparisons with the original. Wow.
>    If this one doesn't test the limits of your system I doubt much
> will -- ever.

FYI: "Switched on Bach" was done by Walter Carlos, now Wendy Carlos.

-Kerry
------------------------------
 
From: lipp@mtu.edu (JOHN I LIPP)
Subject: Re: Puzzle with Class A amplifiers
Date: Thu, 11 Mar 1993 16:50:20 GMT

>No, I think he is asking precisely the right question. A high bias AB amp
>*IS* class A up to the power level where the peak current draw is approx. 
>twice the bias current. Above that it is class AB. So the big Krell's,
>Thresholds etc specc X watts class A into 8 ohms, 2X watts (no mention of
>class A) into 4 ohms, 4X into 2 ohms and so on.
>
>Which is fair enough. Better to have an amp that runs AB on peaks than
>one that clips... I think you are confusing class A with single ended
>design, in which all the power is class A (but there won't be very much :-)).
>
>Class A operation is defined by the fact that the output devices remain in
>their linear region (ie they don't turn off), see the FAQ in rec.audio,
>not be a particular topology.

I'm not sure that you are the one that understands how class-A
amplifiers exactly work.  First, class A amplifiers (or the class-A
region of operation) is most commonly defined as the region where the
output stage device(s) are both operating (i.e. "biased") in the active
region as opposed to the cutoff region (you used the term linear... bad
choice of word).

There are several topologies that are class-A with various benefits.
You can have a standard emitter-follower output stage biased by a
constanct current source in a "single-ended" affair.  This circuit has
the property that the positive voltage swing can draw as much current
as the power supply/output transistor can muster, but can only draw as
much current as the constant current source can supply during a
negative voltage swing.

In a push-pull complimentary emitter-follower output stage when one
transistor is providing voltage, the other is acting as a constant
current source supplying "bias" current.  Thus, due to this symmetry,
the problem of limited output current on the negative voltage swing is
eliminated.  You can call the stage class-A if you want, but is now
just acting as a high-current biased class-AB stage.

An example of a pure class-A stage would be a differential transitor
pair (aka long-tailed pair).  Neither the positive or negative voltage
swing is able to draw more current than the constant current source
provides.  The hallmark of a pure class-A circuit is that it draws the
same amount of current, hence the same amount of power, under any and
all operating conditions.

Now it is possible in the real world that the current sources are not
perfect, but have a finite output resistance and thus the bias current
becomes a function of some voltage in the circuit which can always be
related to the output voltage.  Thus, the bias current level, and
consequently power consumption, can vary with output power.  The
push-pull "class-A" emitter-follower stage is a perfect example of
this.

You are right that having an amplifier suddenly and harshly clip
because you have overdrawn in terms of current, and for that reason one
would not want a pure class-A output stage in an amplifier unless you
make absolutely certain that clipping will never occur in the
application at hand...

> In reality, many class-A amplifiers
>> are as you said just very highly-biased class-AB amplifiers, with the result
>> being that the bias current goes up under full output and lower loads. 
>Huh? The current consumption goes up, but the bias current doesn't, since
>more of it is being diverted to the speakers. That is why class A amps are 
>most efficient at full power...

See the discussion of the push-pull stage above.  Under full power
output a class-A stage of this nature can supply MORE current than the
bias current.  The only way for this to happen is for it to draw more
power... otherwise the law of conservation of energy is violated.

>> The reported benefit of class-A is the belief that since the average amount of
>> power drawn via music is small, a class-A amplifier essentially remains in a
>> static state.  That is, the sound quality does not change because the power drawn
>> to the speakers is insignificant and doesn't disturb the "tuning" of the
>> amplifier.
> Well, I've never heard this, but then...
>What is the "tuning" of the amp in this context?    

Tuning could be used to refer to the locations of poles in zeros in the
transfer function which determine stability under feedback and the
shape of the amplifier response in the audio region.  These things
change/are functions of the bias current.  Keep in mind that to a 5 kHz
sine wave, the effect of a 50 Hz sine wave looks like a change in the
biasing point of the amplifier, and hence tuning is an issue of
importance.  Or tuning could refer to the biasing of the amplifier and
its stability.  Here I was refering to the former.

/***************************************************************************\
*  John Lipp   *  Loudspeaker design pseudo-expert and software developer   *
* lipp@mtu.edu * (Working on amplifier and surround-sound psuedo-expertise) *
\***************************************************************************/
 

------------------------------
 
From: daver!cypress.com!piglet.cypress!ayb@uucp-gw-2.pa.dec.com (Ajay Bawale/PROM)
Subject: Kef 103.4 vs B&W 804
Date: Thu, 11 Mar 1993 16:32:19 GMT

>>clee@ncsa.uiuc.edu (Cassian K. Lee) writes:
>> Are there other speakers that are better than these two in the same price range??
>> I listen EXCLUSIVELY to classical music.

Since you listen exclusivley to classical I unhesistantingly recommend
auditioning Apogee Minors. They are in the same price range. Also, try
out some of Magnepan's offerings. IMHO, ribbons and electrostatics are
better suited for classical music than cone speakers in the same price
range. :-).
---

------------------------------
 
Date: Thu, 11 Mar 93 14:56:32 EST
From: Scott Dorsey <kludge@grissom.larc.nasa.gov>
Subject: Op-Amps

Has anyone out there used any of the Elantec op-amps, like the EL2044
and the like, for audio applications?  Some of the specs look like they
might be quite interesting.
--scott

------------------------------
 
Date: Thu, 11 Mar 1993 11:24:53 -0800 (PST)
From: Ed Faulkner <faulkner@beta.tricity.wsu.edu>
Subject: PCM63P

I would like to update the D/A converters (TDA1540, and analog sections)
in my Nak OMS-5 to the Burr Brown PCM63 "if" possible. My first concern is
how the over sampling feature works. Comparing a schematic in the BB data
book to that of my player reveals similar (?) signals between the digital
filter and the D/A chip. The data book mentions that "up to" 8X over
sampling is possible using the PCM63, my deck is a 4X type. Does the over
sampling process occur within the PCM63 or is an external signal applied that 
forces this to happen.
                                                                          
 
The signals from my decks digital filter chip and those shown for the BB 
appear to be the same with the exception of a possible inversion. Does 
anyone have additional information that would help me determine weather 
or not this is possible? Is the Ultra-Analog D/A available for direct 
purchase and usable under these conditions?                       
                                                                          

______________________________
Ed Faulkner                   \  Everything should be made as simple 
Computer Maintenance Tech II   \   as possible, but not simpler.
Washington State University     \        --Albert Einstein
100 Sprout Rd.                   \
Richland, WA 99350                \
faulkner@beta.tricity.wsu.edu      \_____________________________________

------------------------------
 
Date: Thu, 11 Mar 93 15:22:47 EST
From: Chris Andrichak <ANDRICCS@DUVM.OCS.DREXEL.EDU>
Subject: RE: Adcom Tuner

Pre PS: Sorry about that junk in my last message (not really undeliverable)

I have owned an Adcom tuner for about 2.5 years. The best thing I can say about
it is that nothing about it is really bad. Unfortunately nothing is all that
impressive, either. It tunes ok, sounds ok, and doesn't have quite enough
presets (12 is my optimum number). It is rack mountable. But I don't listen
to the radio all that much (re: Mr. T.E.Landrum in v20#7), so....
    I've never heard the Proton. I'd try and get a used HK Citation 23 or
    a used Magnum Dyanlab.

Chris Andrichak

My music tip of the moment: The Brand New Heavies self titled first album

------------------------------
 
From: torgd@tolstoy.lerc.nasa.gov (Russell DeAnna)
Subject: FOR SALE: McIntosh Tuner
Date: Thu, 11 Mar 1993 20:42:49 GMT

I still have not sold this tuner. I'm
thinking about trading it for an amp, but
before I do I thought I'd list it once more.

McIntosh MR 71 Tuner
Both variable and fixed output
mono/stereo selector
rotary tuning dial
signal level meter and FM multiplex meter and control dial

Excellent Condition: front panel is gold and free of scratches;
glass window also clean.
Price: $400.00
Send e-mail if interested
--
  Russell G. De Anna            
  E-mail:  torgd@tolstoy.lerc.nasa.gov 
  phone:  (216) 433-3385

------------------------------
 
From: dwf@kepler.unh.edu (Dennis W Fitanides)
Subject: where can I find used high end audio?
Date: 11 Mar 1993 20:51:02 GMT

Hi 

  Does anyone have any good sources for used High End audio via mail order?

Thanks
Dennis

------------------------------
 
From: bhmd1464@altair.selu.edu
Subject: Wanted: Kappa-9's and other kappas
Date: 11 Mar 93 15:39:10 -0600

I have posted this a couple of times in the past but I haven't found any
Kappa-9's so I'll keep on looking.

I am interested in buying a pair of infinity kappa-9 speakers.  I will
drive almost anywhere to get them or I will pay for shipping.
If you own a pair and would like to sell them or if you know of a pair that is
for sale, I'll make it worth your time.  

Thanks to all of you who have responed with Kappa-8's and 7's for sale...
I am interested in these as well but I am mainly interested in the 9's
so I wouldn't be willing to pay an awful lot for 7's or 8's and I don't
want to insult happy owners with an offer that might seem too low.  In any
case, if you have kappa, I have cash.

Brian Acosta
(504) 345-8904  home
(504) 543-9701  voice mail
(504) 345-2035  work
(504) 345-3255  fax
 

------------------------------
 
From: MATGBB@LURE.LATROBE.EDU.AU (BYRNES,Graham)
Subject: Re: Puzzle with Class A amplifiers
Date: Thu, 11 Mar 1993 22:50:01 GMT

In <1nkrtsINNqsg@uwm.edu> gfl@herahera.cc.bellcore.com writes:
> 
> Hugh-
> 
> Why did you puick class-A operation for this question?  It's irrelevant.
No, it is not.
> Now, from your post line, you'ree an engineer.  What's the variable
> that determines ability to double power into low Z loads?  Current!
> 
> That's it.  There is no more.

But what determines the class A limit of an amp? The *Current*.
Suppose you are drawing an increasing pos. current from the amp. Then, assuming
a complementary output stage, progressively more current comes through the 
npn (or n-channel fet etc) and progressively less through the pnp (or
p-channel). At the stage where the current through the npn is about double
what it was at idle, the pnp turns off completely. That is when the amp
ceases to be class A. Every AB amp is class A for sufficiently small (current) 
signals: what we normally refer to as a Class A amp is one that remains in
Class A up to its specified power limit, as set by its max voltage swing.
However lower Z will draw more current for the same voltage, hence an
amp that is A for 8 ohm speakers may be AB for 4 ohm (or 2 ohm or etc).
Graham

------------------------------
 
From: chucko@freud.arc.nasa.gov (Chuck Fry)
Subject: "Pooge" tips for novice
Date: Thu, 11 Mar 1993 23:33:09 GMT

I recently picked up some Sony mid-fi equipment to replace some older
stuff that was beginning to crap out.  The items in question are a
CDP-C615 CD changer and an STR-AV1070 receiver.  The sound quality is
good, but I can hear some artifacts of slew-limited distortion on my
better CDs.  

I wonder if anyone out there could share some experience on "poogeing"
this equipment.  Some specific questions:

 (1) What op amps do people recommend for line-level signal processing
these days?  The Burr-Brown OPA2604 looks good, but the spec sheet
smacks of snake oil and green pens (i.e. lots of feel-good phrases and a
few non-specs).	 Are there any other op amp types that are especially
good in line-level, low-gain applications?

 (2) Are there any easy improvements to be made to the power supplies to
better handle transients?  Has anyone played with low-ESR filter caps
designed for switch-mode power supplies?

 (3) What types of capacitors are recommended to replace aluminum
electrolytics in: DC blocking applications?  Power supply bypassing? 
Etc.

 (4) Any other tips specific to recent Sony equipment?

Thanks for your indulgence.
-- 
     Chuck Fry  chucko@freud.arc.nasa.gov  chucko@ptolemy.arc.nasa.gov
   Join the Silicon Valley protest against 55 MPH!  Email me for details.
	    I alone bear responsibility for the claptrap above.

------------------------------
 
From: daniel@netcom.com (Sam Daniel)
Subject: International Audio Review
Date: Thu, 11 Mar 1993 23:18:11 GMT

Can anyone tell me if IAR is still being published?  If so, what was
the last issue you received, when did you receive it, and what is the
current mailing address and subscription rate?

Thanks in advance for any assistance....
-- 
*
Sam Daniel          *   UUCP (Smart):  daniel@netcom.com
Paramax Systems     *         (Dumb):  {...}!uunet!netcom!daniel
1001 W. Maude Ave.  *          Voice:  1-408-235-2661
Sunnyvale, CA 95131 *     Disclaimer:  It's only my opinion, but it's
                                       a DAMN good one...

------------------------------
 
From: michi@ptcburp.ptcbu.oz.au (Michael Henning)
Subject: Need info on Sony TA-F 1090 ES amplifier
Date: Thu, 11 Mar 1993 23:55:00 GMT

A friend of mine offered to buy an amplifier for me in Singapore and have
it shipped to Australia. I was initially after the TA-F 870 ES, which is
not available here. On enquiring, my friend was told that this model
is no longer made, and that the TA-F 1090 ES is the successor.
Needless to say, Sony Australia don't distribute that model either, so
now I'm trying to find out more about the 1090.

If anyone has basic details, a data sheet, listening experience, or anything
else relevant on the 1090 (or any other high-end ES model), I'd be very
pleased to hear from you. Also, Australia runs on 240V, so if you have any
info on whether the amp is available in a 240V version, I'd appreciate it
if you drop me a line.

							Thanks,

								Michi.
-- 
      -m------- Michael Henning                 +61 75 950255
    ---mmm----- Pyramid Technology              +61 75 722475 FAX
  -----mmmmm--- Research Park, Bond University  michi@ptcburp.ptcbu.oz.au
-------mmmmmmm- Gold Coast, Q 4229, AUSTRALIA   uunet!munnari!ptcburp.oz!michi

------------------------------
 
From: procter%remarque.Berkeley.EDU@ucbvax.Berkeley.EDU (Steven Procter)
Subject: B&W 801 mods, environments
Date: 12 Mar 93 02:40:05 GMT

I would like to find out about modifications to the 801s, or other
techniques for making them sound better such as using a particular 
type of amp, speaker wire, tube, etc.

I have listened to them several times in stores and almost love them.
Nothing else I have heard delivers the excitement of the 801s.  But
on some recordings they are so harsh that I don't want to listen at all.

I have a pair of 805s which don't have this problem in my system, which
includes a tube amp and a hybrid preamp.  Is it likely that the demo systems
are responsible for the unpleasantness?

								Steven

------------------------------
 
From: shetline@bbn.com (Kerry Shetline)
Subject: Re: Low price interconnect & cable
Date: 12 Mar 1993 02:47:04 GMT

In article <1nngfcINNcpj@uwm.edu>, sheen@src.bae.co.uk (Andy Sheen) wrote:
> > It doesn't seem to me that you can have it both ways.
> 
> I think this is an extreme view. For any two cable sets there is either
> going to be a "glaring" difference or a "subtle" difference (or indeed,
> none at all); but it'll depend on the two cable sets compared.

I was meant for any particular comparison, not for all possible
comparisons, although once the comparisons are between items not so
extremely different as say, rusty barbed-wire and silver-plated oxygen-free
copper tree trunks, it might well be applicable.

> let alone a new set of cables. I'm quite prepared to try some double blind
> testing if you want, but finding someone who is interested enough to spend
> time do it might prove to be a toughie - my wife certainly isn't!!

I can understand that such testing can be difficult to arrange, but in
light of that people should have a healthy respect for the power of their
imagination to change what they think they hear.

> I know cabling makes a difference at higher frequencies <100k, I've seen
> gross distortions myself on an oscilloscope so why not at a lower frequency
> but at much reduced distortion levels. I also know that just because you
> measure something it doesn't necessarily mean that it is exactly that since
> your measuring instrument could be deficient or you could be looking at the
> wrong thing.

A cable, be it speaker cable or interconnect cable, has the properties of
reactance, resistance, and capacitance. Viewed this way, the effects of
cable on sound should be like that of some sort of simple filter. (For
speaker wire, the complex load that a speaker represents adds to the
potential for problems far more than the load presented to a line-level
cable by a standard audio jack.) But unless the wire is horribly made or
ill-suited to a particular application, it will be a VERY subtle filter.
I'd have to run this past an engineer (I know a couple on rec.audio.low-end
who would probably be willing to provide some input) but I'd bet that
frequency response deviations should be well under 0.1 dB, and phase shifts
easily less than 1 degree even at the frequencies well beyond 20 kHz for
any reasonable piece of cable.

Also, a wire may serve as an antenna for stray electro-magnetic noise.
Again, unless the cable is badly made the level of noise that it picks up
should be slight.

> It is also perfectly possible (I'm out on a limb here, so no
> flames please) that what you hear depends on other information in the
> surroundings and not on single frequencies. This is certainly the case for
> vision (Land and his colour constancy experiments form the 40's and 50's)
> so why not for hearing ? People have claimed, and in length on this list,
> that the human ear is a very fine measuring instrument (I've seen claims in
> the thread about DAC's that people can hear differences in timing in the
> picosecond range).

The human ear is a microphone made out of meat. If it weren't for some
powerful processing by the brain, we'd be lost. But the brain's processing
of sound can get out of hand. If you don't believe in your mind's ability
to affect the way things sound, consider this experience common to nearly
all of us: You hear a song, but you can't make out the lyrics. Later, you
finally figure them out, somebody else tells you, or you read the lyrics.
>From then on, when you hear the song the words sound like they are supposed
to sound. I don't mean that the words are simply more intelligible -- THEY
SOUND DIFFERENT. The effect is entirely in the brain's processing, not in
the signal.

The reason for this comes from the nature of the task that the ear and
brain
must perform to parse sound and music. The ear receives a jumble of
frequency
components from separate sources simultaneously, and the brain must discern
which components are related and identify the source. To exaggerate the
dillema,
suppose I gave you the number 42, and said that it was obtained as the sum
of a
set of numbers, and asked you to guess the set. There is no way for you to
reasonably approach the problem without some expectations as to the number
of
items in the set, and without good guesses for most of those items.

As I said, this is an exaggeration, but the analogy holds. Hearing requires
active application of expectation to processing, probably more than any
other
sense. This is why it is quite possible for some people to REALLY HEAR
differences in sounds that are created, quite literally, inside their
heads. And
all the more reason why people should demand, of themselves as well as
others,
objective testing. Note that I don't say explanations. It is possible for a
thing to be without complete explanation (e.g. the exact effect of aspirin
on
body chemistry and the neural system) but objectively testable (clinical
trials
with control groups).

As for the Land experiments, they didn't rule out the use of simple optical
measurements. The merely provided maps of the response curves of the eye
and the interaction of various stimuli. If anything, they showed what could
fool the eye that wouldn't fool a machine, not the other way around.

> I have experience with both my close family and friends saying there was an
> audible difference in cables - none of these are anything like audiophiles
> and in many cases didn't even know what was being done to the system. The
> same people have heard differences in power cables - something I was
> extremely dubious about until I heard it.

In 'A/A' comparisons -- comparisons in which listeners are told that a
switch is being made, but nothing actually changes -- the listeners still
manage to come up with all sorts of nuances to distinguish A from A that
obviously can't be there. At the same time, I know of no conclusive
demonstrations in favor of any of the esoteric cables. (See one of recent
issues of the The $ensible Sound (within the last six months) for more
info.)

> If you don't believe there is a difference then thats up to you.  I am quite
> happy to spend a few hours or so trying things out - it's a hobby for me.
> The new cable isn't the best thing since sliced bread but I do find
> it interesting that different cables can (in my view) affect the sound.

It's not this that I'm objecting to anyway. It's this sort of stuff from a
previous post about 0.5 m interconnects in the $200 range:

        Cardas Quadlink-5:
                Really nice midrange and bass (smooth & lush), but the
high-end
                is too curtailed, making it sound too warm.
        Cogan-Hall Reference Intermezzo:
                Well balanced, but not extended enough at either end, plus
                midrange isn't quite smooth (violins sound a bit squeeky).
        Kimber Kable KCAG:
                Really transparent, but too forward in tonal balance.
        MIT 330:
                Pretty nice cable, but not in the same league as the
others.
        Tara Labs Rectangular Solid Core (RCS):
                High-end is way too curtailed!

I'm sorry, but I just think is is going overboard. At least this guy stuck
to tonal descriptions and didn't start wandering off into one of the
favorite areas of wirephiles -- imaging -- that's really the most unlikely
thing to be effected by a cable.

> Why resort to specmanship. I don't (try not to) buy hi-fi on specs but on
> what it sounds like. The same goes for cabling; if I can't hear a
> difference I don't buy.

I'm suggesting that even if you do hear it, you should question it.

-Kerry

------------------------------
 
From: yk7m@uvacs.cs.Virginia.EDU (Young-Kuk Kim)
Subject: Opinion about Melos MA110B preamplifier
Date: Fri, 12 Mar 1993 04:03:07 GMT

Hi, audiophiles

Is there anyone having an experience with the Melos line-level 
preamplifier?
I read an excellent review on their headphone amplifier but
haven't found any review on their MA110B preamplifier.

-- Young-kuk Kim


------------------------------
                                        
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