Bypassing caps? How about with wire?

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"Stephen Sank" <bk11@thuntek.net> wrote in message
news:cdv52t$j08$1@reader2.nmix.net...
> One of the most enormous failings of the audio electronics industry
through the years has been
> a direct result of people like you, Mark. "If it looks good on
paper(and on test equipment),
> it has to sound good." One of the WORST sounding power amps I have
ever heard was the Yamaha
> M70. THD & TIM were rated 0.002% from 250mw to 250w at 8, 4 or 2
ohms. Slew rate 200V/us.
> S/N 105db below rated output. Drew an absolutely perfect squarewave
at any audio frequency &
> any power level. But the amp, with music, sounded absolutely
HORRIBLE. Regardless of speaker,
> preamp, cables or any other peripherals, the upper treble was
downright screechy, and despite
> the apparently lively treble, detail in the high treble was obsured
badly. When I switched
> from that amp(which I regrettably owned for a while) to a much older
McIntosh MC2105, which is
> also a transistor amp, and which has far "worse" measured
performance in every way, it was such
> a VAST improvement in sound in every describable way, I couldn't
believe I'd ever been able to
> stand listening to the Yamaha.

Judging by the words in all caps, this amplifier must have been
unacceptable to anyone. Which brings up the question: Why did Yamaha
put this abomination on the market, and why did so many people buy it?

Another question might be: How would you go about designing an
amplifier that meets the specs you mentioned above, yet sounds
"HORRIBLE"? I've mulled the situation over, and I can't think of any
way to accomplish this feat.

Norm Strong

 

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"normanstrong" <normanstrong@comcast.net> wrote in message
news:GnaNc.165810$IQ4.101918@attbi_s02

> Another question might be: How would you go about designing an
> amplifier that meets the specs you mentioned above, yet sounds
> "HORRIBLE"? I've mulled the situation over, and I can't think of any
> way to accomplish this feat.

The obvious way is to slip it past the tests. For example, make an amp that
works great with resistive loads, but clips at the first sign of a reactive
load. That's two transistors and a few resistors, less if asymetrical bad
behavior is desired, even less if the parts are already there and all you
need to do is misdesign them. You might call the results, a "DC-300". It
would be your err, *crowning* achievement as it were. ;-)

A built-in grounding problem might also be possible.

 

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normanstrong <normanstrong@comcast.net> wrote:
>
>Judging by the words in all caps, this amplifier must have been
>unacceptable to anyone. Which brings up the question: Why did Yamaha
>put this abomination on the market, and why did so many people buy it?

I dunno, but it wouldn't be the first time Yamaha has made something that
sounded really horrible but sold well.

>Another question might be: How would you go about designing an
>amplifier that meets the specs you mentioned above, yet sounds
>"HORRIBLE"? I've mulled the situation over, and I can't think of any
>way to accomplish this feat.

By taking the attitude that circuit linearity isn't really very important
since all flaws can be cured with negative feedback. This seemed to be
a very common philosophy in the 1970s, and it resulted in a lot of very
disasterously bad-sounding gear. The terrible sound of some of the early
transistor gear is part of what fueled the whole tube audio renaissance
a decade and a half later.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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Remembering the schematic as best as I can in my head, one glaring aspect was the rather
numerous stages that had small(pf values) caps in the immediate feedback look, which strongly
suggested that the Yamaha people had some difficulties with the HF stability of the amp. In my
experience, when you see things like that in an amp circuit, regardless of amount of global
feedback, the amp will not yield the best sound. In fact, in this particular line of Yamaha
amps(M50 & M70, carried fundamentally over to M40/M60/M80, and then M45/65/85), if you made the
mistake of replacing the predriver transistors with anything but the exact originals, the amp
would go ballistic with ultrasonic oscillation & blow up.
In regard to how they sold the darn things in large numbers, the plain fact is that a lot of
people get impressed by systems that have hyped treble(including a hell of a lot of recording
people, sadly, judging by the average cd release), and will buy something in a hifi store(an
environment usually acoustically absorbtive of treble) after a few minutes listening. How many
of these folks found their ears growing tired of the sound they ended up with is something that
might well be judged by surveying the audio listings on ebay.

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http/stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"normanstrong" <normanstrong@comcast.net> wrote in message
news:GnaNc.165810$IQ4.101918@attbi_s02...
>
> "Stephen Sank" <bk11@thuntek.net> wrote in message
> news:cdv52t$j08$1@reader2.nmix.net...
> > One of the most enormous failings of the audio electronics industry
> through the years has been
> > a direct result of people like you, Mark. "If it looks good on
> paper(and on test equipment),
> > it has to sound good." One of the WORST sounding power amps I have
> ever heard was the Yamaha
> > M70. THD & TIM were rated 0.002% from 250mw to 250w at 8, 4 or 2
> ohms. Slew rate 200V/us.
> > S/N 105db below rated output. Drew an absolutely perfect squarewave
> at any audio frequency &
> > any power level. But the amp, with music, sounded absolutely
> HORRIBLE. Regardless of speaker,
> > preamp, cables or any other peripherals, the upper treble was
> downright screechy, and despite
> > the apparently lively treble, detail in the high treble was obsured
> badly. When I switched
> > from that amp(which I regrettably owned for a while) to a much older
> McIntosh MC2105, which is
> > also a transistor amp, and which has far "worse" measured
> performance in every way, it was such
> > a VAST improvement in sound in every describable way, I couldn't
> believe I'd ever been able to
> > stand listening to the Yamaha.
>
> Judging by the words in all caps, this amplifier must have been
> unacceptable to anyone. Which brings up the question: Why did Yamaha
> put this abomination on the market, and why did so many people buy it?
>
> Another question might be: How would you go about designing an
> amplifier that meets the specs you mentioned above, yet sounds
> "HORRIBLE"? I've mulled the situation over, and I can't think of any
> way to accomplish this feat.
>
> Norm Strong
>
>

 

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Archived from groups: rec.audio.pro (More info?)

In article <GnaNc.165810$IQ4.101918@attbi_s02> normanstrong@comcast.net writes:

> Another question might be: How would you go about designing an
> amplifier that meets the specs you mentioned above, yet sounds
> "HORRIBLE"? I've mulled the situation over, and I can't think of any
> way to accomplish this feat.

One thing is to not specify the things that make it sound horrible, or
measure them in ways that make bad things look good. An easy on, if
there's a 40 or 50 kHz oscillation (and this really can happen with a
badly designed amplifier) is to measure of the bandwidth of 20 Hz to
20 kHz. While I wouldn't say "it sounds horrible" I've run across some
gear that has noise specificed as "A weighted" which pretty thoroughly
attenuates line frequency hum.

I couldn't tell from Stephen's message whether "it measured" or he
actually made measurements himself, trying determine if he could
analyze the problem he was hearing.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

 

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Archived from groups: rec.audio.pro (More info?)

On Mon, 26 Jul 2004 16:33:42 GMT, "normanstrong"
<normanstrong@comcast.net> wrote:

>Another question might be: How would you go about designing an
>amplifier that meets the specs you mentioned above, yet sounds
>"HORRIBLE"? I've mulled the situation over, and I can't think of any
>way to accomplish this feat.

In addition to what Arny and Scott have mentioned, a problem
not so long ago was to specify performance only at full output.

The assumption that all flaws will decrease with signal level
has become *less* true with most modern improvements.

Full signal performance spec's are almost completely
irrelevant for current designs.

Chris Hornbeck
"Vote or Die" - P. Diddy

 

[mark]

Archived from groups: rec.audio.pro (More info?)

My point is that if you claim that an amp sounds bad, or changing caps
sounds good, I think you at least owe the folks to whom you are making
the claim, a reason for your claim, a reason backed up by
measurements. Somthing like the bad bypass cap caused an ultrasonic
oscillation that created terrible high frequency IM distortion (which
is easily measured).

I guess our fundamental disagreement is that I beleive that any
difference that can be heard can also be measured. With FFT
analyzers that can measure 100 dB down and have sub Hz resolution BW,
it is my firm belief that anything you can hear can be measured. It
may be difficult to identify the particular parameter to measure to
account for what you hear, but that is part of the challange.

Mark

 

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"Mark" <makolber@yahoo.com> wrote in message
news:3367f36e.0407261911.1ae2b56@posting.google.com...
> My point is that if you claim that an amp sounds bad, or changing caps
> sounds good, I think you at least owe the folks to whom you are making
> the claim, a reason for your claim, a reason backed up by
> measurements. Somthing like the bad bypass cap caused an ultrasonic
> oscillation that created terrible high frequency IM distortion (which
> is easily measured).
>
> I guess our fundamental disagreement is that I beleive that any
> difference that can be heard can also be measured. With FFT
> analyzers that can measure 100 dB down and have sub Hz resolution BW,
> it is my firm belief that anything you can hear can be measured. It
> may be difficult to identify the particular parameter to measure to
> account for what you hear, but that is part of the challange.

In principle, yes, unless you believe in ghosts and gremlins, the causes of
bad sound can be found and measured. I think Stephen's point is that the
traditional measurements of the time (frequency response, THD, SMPTE-IMD and
damping factor at one frequency, all into resistive loads) didn't identify a
problem, but his ears did. We now have some more sophisticated tests, and
sometimes they'll explain what the problem is -- marginal instability into
real-world speaker loads, for example. Or current-limiting baddies, as Scott
described. There are still, however, stubborn cases of amps that measure
well on all the tests we have, yet sound crummy. That doesn't mean
measurements can't find the problem, just that we haven't devised the right
measurements yet.

Peace,
Paul

 

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"Paul Stamler" <pstamlerhell@pobox.com> wrote in message
news:8enNc.140313$OB3.123267@bgtnsc05-news.ops.worldnet.att.net

> In principle, yes, unless you believe in ghosts and gremlins, the
> causes of bad sound can be found and measured.

It doesn't take belief in gremlins, just a firm belief in the infallibility
of one's own ears. That can be a horrible mistake - sort of like saying "I'm
a professional, I don't need to take the precautions that the most skilled
and productive modern professionals take as a matter of course."

I am reminded of this every time I see the History Channel show about the
DC10 crash at O'Hare. The guys who did the prerequisite slipshod maintenance
on these jets were obviously convinced of their professionalism. So were
their bosses. So was the FAA. The same basic sloppy procedure was used by at
least three airlines. 273 people died getting this straightened out. Ain't
it great that audio is rarely about life and death?

>I think Stephen's
> point is that the traditional measurements of the time (frequency
> response, THD, SMPTE-IMD and damping factor at one frequency, all
> into resistive loads) didn't identify a problem, but his ears did.

I really didn't see a retrospective tone in Stephen's comments. I read about
outdated technology, though.

> We now have some more sophisticated tests, and sometimes they'll explain
> what the problem is -- marginal instability into real-world speaker
> loads, for example. Or current-limiting baddies, as Scott described.

So far so good.

> There are still, however, stubborn cases of amps that measure well on
> all the tests we have, yet sound crummy.

I'd like to see the specifics of even just one such case. IME, when an amp
sounds bad in a reliable listening test, it is one sick puppy.

Case in point, the Dyna 120. One of the most-criticized amps in the history
of audio. Its worst problem was that it was fragile. It's potential
fragility was obvious to anybody who was familiar with the technology of the
day. Here is a 60 WPC amp built with an output pair that virtually all of
its competitors thought made a pretty good 30-50 WPC amp. Unlike tubes, SS
devices aren't very elastic, and that was well-known at the time.

Lots of people must have spent too much time listening to a Dyna 120 that
would show up as being terribly broken in the simplest of bench tests. I
suspect I could slide one in good operational condition past *everybody* who
reads RAP, in a bias-controlled listening test. But not if they could see
what they were listening to. All the old-timers would *know*.

> That doesn't mean
> measurements can't find the problem, just that we haven't devised the
> right measurements yet.

I question the choice of words. There's no doubt that if an amp does it, and
we can hear it, we can measure it with margins of like 100:1. Measuring
waveforms with -100 dB accuracy is a relatively simple operation. I've
accurately and reliably measured the dynamic range of power amps with 110 dB
dynamic range using less than $1,000 worth of equipment. In a few years that
may drop to $100.

The challenge is setting up the tests and doing the analysis and
interpretation of what we measure. To do that you need to be productive
with signals and systems analysis, and experimental design, and
psychoacoustics. How many technical people in audio, more specifically
audio production, are conversant and productive in all three areas?

"Ear versus Gear" was vastly improved from its chaotic state in say 1973, by
means of improving both ear and gear. The ear side of the equation nets out
to be a matter of personal discipline. The gear side of the equation takes
far less self-discipline = you get to play with fancy toys. Guess which one
more people are interested in?

;-)

 

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Mark <makolber@yahoo.com> wrote:
>My point is that if you claim that an amp sounds bad, or changing caps
>sounds good, I think you at least owe the folks to whom you are making
>the claim, a reason for your claim, a reason backed up by
>measurements. Somthing like the bad bypass cap caused an ultrasonic
>oscillation that created terrible high frequency IM distortion (which
>is easily measured).

I wish I had measurements for everything that I think sounds good or bad.
It would sure be nice. And don't think I have spent a lot of time looking.

>I guess our fundamental disagreement is that I beleive that any
>difference that can be heard can also be measured. With FFT
>analyzers that can measure 100 dB down and have sub Hz resolution BW,
>it is my firm belief that anything you can hear can be measured. It
>may be difficult to identify the particular parameter to measure to
>account for what you hear, but that is part of the challange.

That is a substantial and significant challenge. We're finally getting to
the point with the G-L metric that we might have a useful distortion
measurement, too.

The problem with FFT boxes is that they _can_ measure 100 dB down and have
sub Hz bandwidth resolution... and so you are seeing vast amounts of
information, most of which isn't useful. Finding the information that
_is_ useful is the problem.

I have a microphone on the bench today that just has some awful sibilance
issues... but the swept sine response looks just fine, and the impulse
response looks okay. I'm guessing it's some sort of midrange distortion
issue but I don't have any good way of measuring that.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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"Scott Dorsey" <kludge@panix.com> wrote in message
news:ce5msd$a55$1@panix2.panix.com
>
> I have a microphone on the bench today that just has some awful
> sibilance issues... but the swept sine response looks just fine, and
> the impulse response looks okay. I'm guessing it's some sort of
> midrange distortion issue but I don't have any good way of measuring
> that.


As soon as we step away from simple stuff like electronics, and start
measuring acoustical transducers, everything gets crazy.

While "sounds good and measures bad" is controversial with electronics, with
acoustical transducers, its the way of life.

 

[mark]

Archived from groups: rec.audio.pro (More info?)

kludge@panix.com (Scott Dorsey) wrote in message news:<ce5msd$a55$1@panix2.panix.com>...
> Mark <makolber@yahoo.com> wrote:
> >My point is that if you claim that an amp sounds bad, or changing caps
> >sounds good, I think you at least owe the folks to whom you are making
> >the claim, a reason for your claim, a reason backed up by
> >measurements. Somthing like the bad bypass cap caused an ultrasonic
> >oscillation that created terrible high frequency IM distortion (which
> >is easily measured).
>
> I wish I had measurements for everything that I think sounds good or bad.
> It would sure be nice. And don't think I have spent a lot of time looking.
>
> >I guess our fundamental disagreement is that I beleive that any
> >difference that can be heard can also be measured. With FFT
> >analyzers that can measure 100 dB down and have sub Hz resolution BW,
> >it is my firm belief that anything you can hear can be measured. It
> >may be difficult to identify the particular parameter to measure to
> >account for what you hear, but that is part of the challange.
>
> That is a substantial and significant challenge. We're finally getting to
> the point with the G-L metric that we might have a useful distortion
> measurement, too.
>
> The problem with FFT boxes is that they _can_ measure 100 dB down and have
> sub Hz bandwidth resolution... and so you are seeing vast amounts of
> information, most of which isn't useful. Finding the information that
> _is_ useful is the problem.
>
> I have a microphone on the bench today that just has some awful sibilance
> issues... but the swept sine response looks just fine, and the impulse
> response looks okay. I'm guessing it's some sort of midrange distortion
> issue but I don't have any good way of measuring that.
> --scott


Scott,
I'm certainly willing to leave mics and speakers out of this
discussion, they ARE hard to measure. The original discussion was
about putting a 0.01uF cap in parallel with a 10uF electrolytic
coupling cap makes an audible difference in an amplifier which has an
electrical input and an electrical output. The effects of a cap mod
on an amplifier (if any) should be very easiliy measureable.

Mark

 

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Archived from groups: rec.audio.pro (More info?)

"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:hpoag0h5m96grfv0vmqtiq0se8msog11vg@4ax.com...
> On Mon, 26 Jul 2004 16:33:42 GMT, "normanstrong"
> <normanstrong@comcast.net> wrote:
>
> >Another question might be: How would you go about designing an
> >amplifier that meets the specs you mentioned above, yet sounds
> >"HORRIBLE"? I've mulled the situation over, and I can't think of
any
> >way to accomplish this feat.
>
> In addition to what Arny and Scott have mentioned, a problem
> not so long ago was to specify performance only at full output.
>
> The assumption that all flaws will decrease with signal level
> has become *less* true with most modern improvements.
>
> Full signal performance spec's are almost completely
> irrelevant for current designs.

Did you read the specs? They are applicable from full output down to
250 milliwatts.

Norm Strong

 

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Archived from groups: rec.audio.pro (More info?)

On Tue, 27 Jul 2004 15:40:48 GMT, "normanstrong"
<normanstrong@comcast.net> wrote:

>> Full signal performance spec's are almost completely
>> irrelevant for current designs.
>
>Did you read the specs? They are applicable from full output down to
>250 milliwatts.

250 mW into speakers of 89dB SPL/1W/1M sensitivity is 83dB SPL
at one meter from one speaker, 86dB SPL for uncorrelated signals
from two speakers. This is usually greater than 0VU.

The next 60dB or so down from 0VU is what matters. And our
unconscious assumption of monotonicity can lead us astray.

Chris Hornbeck
"Vote or Die" - P. Diddy

 

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Archived from groups: rec.audio.pro (More info?)

Yes, that first 250mW is usually very important in a home or studio environment. The spec
cutoff on THD & TIM at that point is a very well known tactic of manufacturers to avoid bad
looking(relative to given specs) figures that are affected by the amp's noise floor & crossover
distortion. However, I have done low level THD & TIM measurements on the Yamaha amps I
mentioned, and they are still excellent measuring amps down to even 50mW, relative to other
amps I have thusly tested. Hence my opinion that the really bad sound is an aspect of
performance deficiency not measurable with the conventional equipment. I doubt even FFT would
reveal very much to explain the horrible sound of these & most other great measuring/bad
sounding amps.
It has actually become a very widespread opinion among people who listen to reproduced music(as
opposed to those who seem to listen to equipment, in such a way as to convince their own ears
to conform to what the measurements reveal) that one should be highly suspicious of an amp,
preamp, etc., that has really good measurements. This is because it is so frequently the case,
and I think the majority of cases, that the better the specs are, the worse the gear
sounds(within rational limits). Obviously, if one sees really bad specs, like 1% THD or TIM,
or 22dB S/N, one would not expect great sound. But the best amps I have ever heard are often
in the 0.1-0.3% THD/TIM range, such as the Nakamichi PA-7AII, Threshold S/500II and McIntosh
MC2105. Can't name one amp I loved the sound of that was lower than 0.02% on the distortion
specs.

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http/stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:k0vcg0lsf1thku6bedn3f44j9rnnoot6mn@4ax.com...
> On Tue, 27 Jul 2004 15:40:48 GMT, "normanstrong"
> <normanstrong@comcast.net> wrote:
>
> >> Full signal performance spec's are almost completely
> >> irrelevant for current designs.
> >
> >Did you read the specs? They are applicable from full output down to
> >250 milliwatts.
>
> 250 mW into speakers of 89dB SPL/1W/1M sensitivity is 83dB SPL
> at one meter from one speaker, 86dB SPL for uncorrelated signals
> from two speakers. This is usually greater than 0VU.
>
> The next 60dB or so down from 0VU is what matters. And our
> unconscious assumption of monotonicity can lead us astray.
>
> Chris Hornbeck
> "Vote or Die" - P. Diddy

 

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"Paul Stamler"

> In principle, yes, unless you believe in ghosts and gremlins, the causes
of
> bad sound can be found and measured. I think Stephen's point is that the
> traditional measurements of the time (frequency response, THD, SMPTE-IMD
and
> damping factor at one frequency, all into resistive loads) didn't identify
a
> problem, but his ears did.


** Stephen did not produce for us a single scrap of proof of their being a
problem with the amp. He even failed to do ANY sort of scientific
comparison test - so his wild claims should no be taken as fact by anyone.


> There are still, however, stubborn cases of amps that measure
> well on all the tests we have, yet sound crummy.


** It is just too easy to make throw away remarks like that - Paul.

NOTE: When you can prove even *one example* that complies with the above
assertion exists, Paul Stamler will become the most famous man in audio.


>That doesn't mean measurements can't find the problem, just that we haven't
devised the right
> measurements yet.


** More audiophool mantras - how boring.




............ Phil

 

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Phil Allison <philallison@tpg.com.au> wrote:
>"Paul Stamler"
>
>> There are still, however, stubborn cases of amps that measure
>> well on all the tests we have, yet sound crummy.
>
>** It is just too easy to make throw away remarks like that - Paul.
>
> NOTE: When you can prove even *one example* that complies with the above
>assertion exists, Paul Stamler will become the most famous man in audio.

There are examples like that all the time, and that is why we are getting
newer and better measurements all the time. As people find more things
that are audible, they design new measurements to measure them.

If every possible aspect of sound can already be measured, why are there
all of these metrology papers at AES and AAS meetings every year?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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"Scott Dorsey" <kludge@panix.com> wrote in message
news:ce5ne5$lju$1@panix2.panix.com

> Phil Allison <philallison@tpg.com.au> wrote:

>> "Paul Stamler"

>>> There are still, however, stubborn cases of amps that measure
>>> well on all the tests we have, yet sound crummy.

>> ** It is just too easy to make throw away remarks like that -

>> NOTE: When you can prove even *one example* that complies with the
>> above assertion exists, Paul Stamler will become the most famous man
>> in audio.

Thinking about it, there might be an argument about what constitutes
measuring *well* as compared to measuing *unwell*.

For example JJ (ex AT&T Labs) once suggested that anything that measures
with all distortions and noises 100 dB down, is sonically transparent. I
think that criteria is going to stand for an awfully long time.

You see, the actual threshold for hearing noise and distortion is generally
below 70 dB on an instantaneous basis. JJ's other 30 dB relate to dynamics,
exceptional cases, and basic conservatism.

> There are examples like that all the time, and that is why we are
> getting newer and better measurements all the time.

Really?

I was thinking of "new measurements", and I came up with the Geddes/Geddes
criteria for nonlinear distortion. But, its not a new measurement, its a
modified way to analyze data that has been measured for decades. It's not so
much about thresholds but rather about comparing different amounts of
audible distortion, and saying which one "sounds worse" given that both are
audible.

> As people find more things that are audible, they design new measurements
to measure them.

It has been known that nonlinear distortion has been audible for at least 70
years. The Geddes/Geddes paper is about psychoacoustic weighting factors for
distortion products that have been measured in a highly detailed fashion for
decades. It doesn't so much as lower the known thresholds for detection, as
raise them selectively.

> If every possible aspect of sound can already be measured, why are
> there all of these metrology papers at AES and AAS meetings every
> year?

(1) Are they really about metrology, or are they really about something
else, like psychoacoustics?
(2) Three words: Publish or Perish.
(3) Eight words: Professional papers as publicity for a new product.

 

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Arny Krueger <arnyk@hotpop.com> wrote:
>"Scott Dorsey" <kludge@panix.com> wrote in message
>
>> If every possible aspect of sound can already be measured, why are
>> there all of these metrology papers at AES and AAS meetings every
>> year?
>
>(1) Are they really about metrology, or are they really about something
>else, like psychoacoustics?

They are more and more about psychoacoustics, as more of the systems that
we need to measure are systems that use perceptual-encoding methods.

But they are all in some sense about psychoacoustics, because the whole
name of the game, starting in the 1930s with the THD measurement at Western
Electric, is to figure out a way to measure what people are hearing.

>(3) Eight words: Professional papers as publicity for a new product.

There is a huge amount of this, but there is actually less of it in the
metrology world than elsewhere, probably because there isn't much money
in new products there. The JAES is very good about not allowing
this sort of thing but there is a huge amount of it at conventions, though
it's usually pretty obvious. Many of the section folks put the obvious
advertisements together into a single session so everyone can avoid them,
or drop them into the posters area.

Personally, I have nothing against those papers, as long as they do actually
have real technical content. (And some of the ones that don't are still
worthwhile for amusement.... some of the Pioneer-sponsored papers on 96k
audibility just had people laughing in the aisles.)
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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Archived from groups: rec.audio.pro (More info?)

"Stephen Sank" <bk11@thuntek.net> wrote in message
news:ce6hn7$ock$1@reader2.nmix.net

> Yes, that first 250mW is usually very important in a home or studio
> environment. The spec cutoff on THD & TIM at that point is a very
> well known tactic of manufacturers to avoid bad looking(relative to
> given specs) figures that are affected by the amp's noise floor &
> crossover distortion. However, I have done low level THD & TIM
> measurements on the Yamaha amps I mentioned, and they are still
> excellent measuring amps down to even 50mW, relative to other amps I
> have thusly tested. Hence my opinion that the really bad sound is an
> aspect of performance deficiency not measurable with the conventional
> equipment.

Specifically, which Yamaha amp(s) are you talking about?