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  #82   Report Post  
Nousaine
 
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Bromo wrote:

On 4/25/04 1:25 AM, in article ZYHic.26492$IW1.1268676@attbi_s52, "Nousaine"
wrote:

Oh I get it. You have to have a DIY subwoofer like mine before amps ain't
amps.
There aren't currently any consumer passive (or even active) subwoofers

that
have response below 15 Hz.


So the sub 20Hz distortion might not be an appropriate measure.

The largest logical problem with "debunking" is that you are placing
yourself in the position of proving a negative (that a SS amp does NOT have
any differences) - and since all you can do is discredit (which is the idiot
half brother of proper scientific light), we see all kinds of limited tests
with "rewards" and "challenges" - but it beings us back to the problem of
proving negatives.

The time and effort might be spent a bit more productively - perhaps trying
to research and measure all sources of sonic imperfections not already known
- pushing the forefront of hearing sciences, and so on.


So how does one "research and measure all sources of sonic imperfections not
already known"?, that century of telecom, audio and hearing industry research
hasn't already uncovered?

Amp sound? That's been investigated to the bone. Wire sound? Not much need for
that since no interested party has been able to demonstrate the "sound" of
wires when even the most modest of bias-controls have been implemented.

IMO more careful speaker placement and adding a subwoofer and multichannel
processing are the things that will most enhance the sense of playback realism
in consumer audio systems. There's no need for further amp/wire research. I've
done everything possible to allow someone/anyone to demonstrate an ability to
show it even exists.

  #83   Report Post  
Bromo
 
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On 4/25/04 7:20 PM, in article jJXic.34947$aQ6.1879434@attbi_s51, "Stewart
Pinkerton" wrote:

On 25 Apr 2004 14:15:44 GMT, Bromo wrote:

The time and effort might be spent a bit more productively - perhaps trying
to research and measure all sources of sonic imperfections not already known
- pushing the forefront of hearing sciences, and so on.


Actually, since we can already prove that dozens of amplifiers sound
exactly the same below the clipping point, the time and effort would
most definitely be better spent in selecting better speakers, and
placing them in the best position in a well-sorted room.


I agree that is a good use of an end user's time and money - but still - if
people claim to hear a difference, it might be good to do the due diligence
as a scientific sort to see if there is anything to these claims. Some have
been made in the past that haven't helped, but some has been made that did.

Of course, this would destroy 90% of 'high end' mythology - but
perhaps the world would be a better place for that............


Mythology is bad - but I would be careful to discard the grain of truth with
it. Even if the golden eared claimants were incorrect for the reasons
*they* said - there might be something there important for sound
reproduction that they didn't realize.

  #84   Report Post  
Bromo
 
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On 4/25/04 7:18 PM, in article xHXic.34068$w96.2423643@attbi_s54, "Nousaine"
wrote:

Thiels are notorious for requiring a lo of current in the bass (and tend to
be 3 Ohms)


I have a Thiel CS-1.6 in house as we speak. While it does have a relatively
low
impedance there is nothing at all "tough" about the curve.


You will find that if you have extra amps available at the bass end (I know
from the 2.4's) the bass tightens right up and becomes very articulate.
Given the bass cones are about 6" it might not make so much a difference,
but the nearly 8" on the 2.4's sure did.

Magnepans are -- magnepans and then to have a sub 5 Ohm load.


Same as with the Theil. Indeed Magnepan is noted for claiming a nearly
"resisitive" imdedance curve said to be easier to drive. Of course, that's BS
(it has the typical resisitve, capacitive and inductive qualities just like
all
loudspeakers) but the curve is smooth and doesn't vary much over its operating
bandwidth.


Yes, but the Maggies are VERY revealing and tend to require a lot of current
to sound their best. Think of it as driving a very very large cone.


  #85   Report Post  
 
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"It won't be settled - you cannot prove a negative."

It has been suggested we don't prove anything, we fail to disprove. If we
propose that amps of similar electrical specs will sound different and a
listening test shows difference at a level of guessing, we haven't proven
some other amp pair willn't pass the test, we have however shown that it
fails to disprove the proposition that two such amps will sound alike. Do
enough of these examples of failing to disprove and the
confidence/potential that any future pars will sound different becomes so
small that we have little interest/motivation to continue trying to
disprove the proposition. That is the course that concensus building and
the way scientific "truth" is formed. That is the power of the current
benchmark in test results, we are now a good distance down the road that
so many attempts have failed to disprove that we are quickly losing
interest seeking those exceptions to the benchmark.



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"However, the test is still meaningless in one sense. If I look at two
different speaker with very similar dispersion pattern and distorsion
spec, but with completely different frequency response, both speaker
would sound the same after correction with an EQ. Quite meaningless if
the test purpose is to reveal whether there are audible differences
between speakers. The need to EQ shows that there must be some flaws
that has to be corrected, right?"

Wrong, the eqed part is to weed out the folk who eqed their amp to create
an obvious difference. Mr. clark reserves the right to eque his yamaha to
match, thus any difference is now not one introduced by the challenger.
It would be the rare amp these days that is not almost flat 20 - 20 k and
for such an eque is not needed to counter the cheaters. If the cheater
introduces a "flaw" he wants his amp to have the same "flaw" to put them
on the same footing as before the cheater made his change. Any difference
will then be not the now equal "flaw" but the inherent sound of the amps
being compared. Remember, the test is not to find if one amp "sounds"
better or good or anything but different. This is where the cheater does
the eqe of his amp before the test to try to force that difference.

  #87   Report Post  
Bromo
 
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On 4/25/04 7:11 PM, in article WAXic.34897$aQ6.1874234@attbi_s51, "chung"
wrote:

It won't be settled - you cannot prove a negative.


So your real concern with any test is that it does not prove the
negative? How about if you are the testee, and you cannot tell the
difference. Is that good enough for *you*?


Well. Given the speaker load that I am driving I am mostly concerned with
the amount of Oomph I need in order to drive my speakers or those that I
might choose.

For instance, would the Yamaha that we are using as our baseline integrated
be enough to sound good and power my Thiel 2.4's? As I have a lesser
Yamaha, I doubt it.

The contest does not have any value for me, then!
  #88   Report Post  
 
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"The more I read and post in this thread, it seems to me that most of the
effort is trying to discredit a marketing department - and a few
reviewers.

What benefit would I, as a consumer, would get from this effort?
Especially
since it is designed not to help me find an amp that would match my
speaker"

You have got it. The test was designed to do exactly the above. It was
to show that one can save money and stress knowing that a 1 k amp will
sound no different then the 10 k amp found in the hi fi rags and floating
on a sea of review ink. Your concern that an amp has enough current not
to become unstable for a given spl is fine but not the reason for the
test. The condition in the test that says the amps under test don't
exceed stable limits is obvious, we don't want the 10 k amp wimping out on
us so it sounds different for it's overloaded artifacts and thus easily
identified. Your concern is a rather easy calculation done comparing
lowest speaker load and the current limits of the amp, it is a universe
away from and not relevent in the least to the reason for the test to
exist. Your purchase concern is only about numbers, findd any two amps
with similar numbers and you are home free and no difference in sound will
be found.
  #89   Report Post  
 
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"The contest is a silly endevour because of the various loads an amplifier
is
asked to drive into - each speaker is different in impedance and the
amount
of current required in order to get a nice, flat response out of it (or a
response the listener finds to his or her liking)."

Irrelevant and silly on it's face, if we are going to evoke the "silly"
metric into the discussion. In the test situation the speaker is an
independent variable, as is the nature of tests where one tries to hold
equal all but those things being tested. Even with the above truisms, the
yamaha sounded no different then the pass labs. As I recall in the clark
rules, any speaker was an option, any speaker and he still has his 10 k.
On the silly scale your series of red herrings about forcing amps into
current overload falls exactly where? The test is not to verfy the truism
that amps can be driven into overload and will sound different when doing
so. It is however the claim from the high end folk that the mega buck
pass lab and the old few hundred yamaha will sound different because the
former is high end and has inherent qualities, with other things being
equal, there will be a
"night and day" obvious sound easy as pie to identify.

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"Sure, there might be people that fool themselves into thinking that there
is
some ineffable difference between a Yamaha and a Halcro - and given the
way
this test is set up - it is skewed to prefer the Yamaha since the
amplifiers
aren't going to be driven into compression where any differences might be
seen."

No one cares about driving amps into the limits of their ability to
provide current. Any two amps can be done so and is a empty exercise to
do the obvious. The test is about driving speakers as is done in typical
high end systems. Those who advocte "night and day" differences in sound
don't even bdgin to drive their amps to be able to make their claims.
They will make their claims with easy to drive speakers using amps whose
current limits are rarely reached. The way you state your objection is a
red herring for the test and the reasons it was created. The one rule
that contains all your objections is the one that says amps are not to be
driven above current limits, including the red hot latest thing the hi fi
rags are all goo goo about and the latest example of "night and day" sound
difference; which takes account of your "skewed" crack. That someone can
mention that a load can potentially be found to exceed current limits is
trivial and irrelevent.


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"Yes - this makes this sort f test rather useless in information or
enlightenment.

If I buy sme Maggie 3.6R's I has better get an amp with more cajones than
the Yamaha integrated, for instance.

If I get a Lowther horn speaker - I would do with a lot less power.

I do not see how this "challenge" serves anyone but the ego of the
"debunker"..."

And whose ego is served by restatements of the truism that various
speakers have various current demands at the extremes, which was never at
issue? Whose ego is served by inserting red herrings into the discussion?
Whose ego is served by arguing apples and oranges and distorting the
reasons for the tests being done and concluding one's purchasing decisions
have not therefore been served. And most important, whose ego is served
if one can now conclude that the ego of another is not at issue either and
can be ignored as irrelevant?
  #92   Report Post  
Stewart Pinkerton
 
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On 25 Apr 2004 19:22:27 GMT, Bromo wrote:

On 4/25/04 1:38 PM, in article 7ISic.32063$w96.2204064@attbi_s54, "Stewart
Pinkerton" wrote:

But, if you don't see it - feel free to take the "40Wpc into 8 Ohms at 1Khz"
integrated and try to drive a Thiel 7.2....


No reasonable person would try such a thing. What is your point?


The point I was making is that the "challenge" when hyped (a $10k "prize is
hype in this case) might make an average consumer think that any old amp
low, mid or hi-fi was capable of driving any old speaker because "they sound
the same."


And that would be true, except for a small number of 'high end'
speakers, such as the Thiel you mention. Anyone with enough knowledge
of the market to be considering purchase of one of these expensive
'audio nasties', might reasonably be presumed also to be aware of
their drive requirements. If not, one would certainly hope that the
sales droids at the speaker store would enlighten him!

I have an AVR200 that used to drive my Thiel 2.4's - I now use a NADS200 to
do the same - the articulation and bass response improved noticably due to
the power - and according to the data sheet I had up to 90W available to do
that (1kHz at 4Ohms was supposed to be 140W). The extra current really
helped the sound I figure when driving that speaker. Made a difference,
when I expected very little.


I'm sure it did, but this has nothing to do with the claims made by
so-called 'high end' amp manufacturers, or their partners in crime -
the ragazine reviewers.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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Stewart Pinkerton
 
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On Sun, 25 Apr 2004 23:40:59 GMT, Bromo wrote:

On 4/25/04 7:20 PM, in article jJXic.34947$aQ6.1879434@attbi_s51, "Stewart
Pinkerton" wrote:

On 25 Apr 2004 14:15:44 GMT, Bromo wrote:

The time and effort might be spent a bit more productively - perhaps trying
to research and measure all sources of sonic imperfections not already known
- pushing the forefront of hearing sciences, and so on.


Actually, since we can already prove that dozens of amplifiers sound
exactly the same below the clipping point, the time and effort would
most definitely be better spent in selecting better speakers, and
placing them in the best position in a well-sorted room.


I agree that is a good use of an end user's time and money - but still - if
people claim to hear a difference, it might be good to do the due diligence
as a scientific sort to see if there is anything to these claims. Some have
been made in the past that haven't helped, but some has been made that did.


That is the exact purpose of the various amp and cable challenges.

Of course, this would destroy 90% of 'high end' mythology - but
perhaps the world would be a better place for that............


Mythology is bad - but I would be careful to discard the grain of truth with
it. Even if the golden eared claimants were incorrect for the reasons
*they* said - there might be something there important for sound
reproduction that they didn't realize.


Interesting that, despite your apparent (and quite reasonable)
standpoint that adequate power is all that matters, you are *still*
buying into the notion that there may be some 'magical' ingredient
that we just don't know about. The real truth is, that P.T. Barnum is
alive and well................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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Stewart Pinkerton
 
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On 25 Apr 2004 23:44:29 GMT, Bromo wrote:

Yes, but the Maggies are VERY revealing and tend to require a lot of current
to sound their best. Think of it as driving a very very large cone.


It's no different electromechanically from driving a very small cone,
only the dispersion pattern varies.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

  #95   Report Post  
Nousaine
 
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Bromo wrote:

On 4/25/04 7:18 PM, in article xHXic.34068$w96.2423643@attbi_s54, "Nousaine"
wrote:

Thiels are notorious for requiring a lo of current in the bass (and tend

to
be 3 Ohms)


I have a Thiel CS-1.6 in house as we speak. While it does have a relatively
low
impedance there is nothing at all "tough" about the curve.


You will find that if you have extra amps available at the bass end (I know
from the 2.4's) the bass tightens right up and becomes very articulate.
Given the bass cones are about 6" it might not make so much a difference,
but the nearly 8" on the 2.4's sure did.


What you offer is a "guess." What I offered is an analysis of the imedance
curve of a given model.

Magnepans are -- magnepans and then to have a sub 5 Ohm load.


Same as with the Theil. Indeed Magnepan is noted for claiming a nearly
"resisitive" imdedance curve said to be easier to drive. Of course, that's

BS
(it has the typical resisitve, capacitive and inductive qualities just like
all
loudspeakers) but the curve is smooth and doesn't vary much over its

operating
bandwidth.


Yes, but the Maggies are VERY revealing and tend to require a lot of current
to sound their best. Think of it as driving a very very large cone.


What??? I think of it as a very large diaphram that requires no stroke and the
low impedance will suck as much power out of the ampliifer as it can. They do
have low sensitivity. But they do not blow up ampliifers. They just will only
play so loudly.



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"Well. Given the speaker load that I am driving I am mostly concerned
with
the amount of Oomph I need in order to drive my speakers or those that I
might choose.

For instance, would the Yamaha that we are using as our baseline
integrated
be enough to sound good and power my Thiel 2.4's? As I have a lesser
Yamaha, I doubt it.

The contest does not have any value for me, then!"

Irrelevant, trivial, apples and oranges with regard to the reasons the
test exists; and especially so with regard to your needs. If you are
interested design a test to serve your needs, don't tap dance about
rhetorically trying to shoehorn your needs into a test which never was
about your needs. Needs and purchasing decisioons etc. were never at
issue, only the claims of those saying there are inherent obvious "night
and day" easily heard differences between amps with similar electrical
properties. Mr. clark and others have set up a situation where those
claims can be fairly evaluated in a repeatabvle manner. Your test of
needs will have to await another day.
  #98   Report Post  
Nousaine
 
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Bromo wrote:

On 4/25/04 7:20 PM, in article jJXic.34947$aQ6.1879434@attbi_s51, "Stewart
Pinkerton" wrote:

On 25 Apr 2004 14:15:44 GMT, Bromo wrote:

The time and effort might be spent a bit more productively - perhaps

trying
to research and measure all sources of sonic imperfections not already

known
- pushing the forefront of hearing sciences, and so on.


Actually, since we can already prove that dozens of amplifiers sound
exactly the same below the clipping point, the time and effort would
most definitely be better spent in selecting better speakers, and
placing them in the best position in a well-sorted room.


I agree that is a good use of an end user's time and money - but still - if
people claim to hear a difference, it might be good to do the due diligence
as a scientific sort to see if there is anything to these claims. Some have
been made in the past that haven't helped, but some has been made that did.


You think that due diligence hasn't been made in this aspect? Please. By 1990
there had been conducted 2 dozen bias-controlled tests on power amplifiers
where never once was it shown that nominally competent amplifiers were shown to
have audible differece.

The 3 tests that showed otherwise revealed a comparison between a 5-wpc and a
400-wpc amplifier' an amplifier with an obvious operating problem and an
amplifier with a high-output impedance where the frequency response at the
speaker terminals was either not recorded or not measured.

Subsequent to that I personally proctored a challenge where an experienced
audiophile (and store owner) showed he was unable to reliably identify his
personal reference amplifier (Pass Aleph) from a used Yamaha integrated
amplifier in his own system using his personally selected recordings under
cable swap and switched conditions over 2 days of experimentation.


Of course, this would destroy 90% of 'high end' mythology - but
perhaps the world would be a better place for that............


Mythology is bad - but I would be careful to discard the grain of truth with
it. Even if the golden eared claimants were incorrect for the reasons
*they* said - there might be something there important for sound
reproduction that they didn't realize.


We've done enough testing of specific claims to have laid that idea to rest.
There is no underground grain-of-truth resting just below the surface. If there
were then someone, somewhere would have stumbled on it over the past 30 years
of searching.
  #99   Report Post  
John Atkinson
 
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Bromo wrote in message
...
I am looking at a Halcro Ad on this month's Stereophile (pg. 15, May '04)
right now...If you measure any deviation in the RIAA curve...you have
caught them in a lie and you can feel confident in debunking them.


You can my measurement of the Halcro dm10's RIAA error in our on-line
review reprint: http://www.stereophile.com/amplifica...ro/index5.html.
The deviation from the specificed curve is indeed minimal, other than
the incorporation of the IEC-specified low-frequency rolloff.

John Atkinson
Editor, Stereophile
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Thomas A
 
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wrote in message news:uoZic.21636$YP5.1630698@attbi_s02...
"However, the test is still meaningless in one sense. If I look at two
different speaker with very similar dispersion pattern and distorsion
spec, but with completely different frequency response, both speaker
would sound the same after correction with an EQ. Quite meaningless if
the test purpose is to reveal whether there are audible differences
between speakers. The need to EQ shows that there must be some flaws
that has to be corrected, right?"

Wrong, the eqed part is to weed out the folk who eqed their amp to create
an obvious difference. Mr. clark reserves the right to eque his yamaha to
match, thus any difference is now not one introduced by the challenger.
It would be the rare amp these days that is not almost flat 20 - 20 k and
for such an eque is not needed to counter the cheaters. If the cheater
introduces a "flaw" he wants his amp to have the same "flaw" to put them
on the same footing as before the cheater made his change. Any difference
will then be not the now equal "flaw" but the inherent sound of the amps
being compared. Remember, the test is not to find if one amp "sounds"
better or good or anything but different. This is where the cheater does
the eqe of his amp before the test to try to force that difference.


Ok, this was what I suggested from start, but Mr Pinkerton said that
it was "cheating" to chose e.g. a DC-coupled amp + an amp with its -3
dB point between 5-10 Hz (such as the Halcro). Using an Ino Audio
speaker system it would be not be easy, but possible, to detect the
Halcro in a blind test.

T



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Bromo
 
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On 4/26/04 1:34 PM, in article zKbjc.41838$IW1.2009846@attbi_s52, "Stewart
Pinkerton" wrote:

I agree that is a good use of an end user's time and money - but still - if
people claim to hear a difference, it might be good to do the due diligence
as a scientific sort to see if there is anything to these claims. Some have
been made in the past that haven't helped, but some has been made that did.


That is the exact purpose of the various amp and cable challenges.


The problem is that it is *not* due diligence, but grandstanding rather
loudly !

Real due diligence wopuld involve getting the amplifiers in question and
doing both double blind testing with a variety of speaker systems and a
variety of sonic and electrical measurements.

Not some silly $10k "challenge"

  #106   Report Post  
Thomas A
 
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much snipped...

We've done enough testing of specific claims to have laid that idea to rest.
There is no underground grain-of-truth resting just below the surface. If there
were then someone, somewhere would have stumbled on it over the past 30 years
of searching.


Tom,

I agree that there is not much that differs amps during music
listening and using 99.9% of loudspeakers of the market, and standard
DBT testing. But if one wants to find out any putative difference, the
test methodology needs to be the most sensitive around. The
before/after listening tests are far more sensitive that just
comparing two amps A/B, since you are comparing the amp with a bypass
cable (the "before" signal). I've posted the link befo

http://www.sonicdesign.se/amptest.htm

I am not saying that there will be audible differences when comparing
the traditional DBT way, but putting things to "rest" does not mean
that there are differences, explained by physical terms, that can be
judged to be significant different. It will, however, have probably
have little practical meaning for the user. It can also be a
preference to have an amp where the spec are far below the audible
limit thereby it will warrant such a market. (I am not talking about
expensive amps which have poor spec here, but those having high-end
spec and thus in general more expensive.)

T

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"The problem is that it is *not* due diligence, but grandstanding rather
loudly !

Real due diligence wopuld involve getting the amplifiers in question and
doing both double blind testing with a variety of speaker systems and a
variety of sonic and electrical measurements.

Not some silly $10k "challenge""

Ah, the silly metric again. If no difference can be heard any electrical
difference is irrelevant by definition. The noise level on this topic has
always been highish on the part of all. The cash is indeed relevant in an
intresting sort of way. One metric, indeed silly, is the compulsive use
of price as some reason to think an amp or wire will "sound" accordingly.
To counter with a cash motivation is an ironic balancing of the scales, a
simple purgative of toxic self definition and a form of conspicuious
consumption. The benchmark now in place has been done by the sum of tests
with all manner of gear.

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Stewart Pinkerton
 
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On Mon, 26 Apr 2004 23:54:59 GMT, Bromo wrote:

On 4/26/04 1:34 PM, in article zKbjc.41838$IW1.2009846@attbi_s52, "Stewart
Pinkerton" wrote:

I agree that is a good use of an end user's time and money - but still - if
people claim to hear a difference, it might be good to do the due diligence
as a scientific sort to see if there is anything to these claims. Some have
been made in the past that haven't helped, but some has been made that did.


That is the exact purpose of the various amp and cable challenges.


The problem is that it is *not* due diligence, but grandstanding rather
loudly !

Real due diligence wopuld involve getting the amplifiers in question and
doing both double blind testing with a variety of speaker systems and a
variety of sonic and electrical measurements.

Not some silly $10k "challenge"


The choice of speaker system is free to the challenger, so what's your
problem? BTW, electrical measurements are irrelevant, we're talking
about *sound* quality here. Once a difference in *sound* has been
established, it's easy enough to pin it down, because it is IME
*always* tied to a gross technical problem, nothing at all subtle!

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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Nousaine
 
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(Thomas A) wrote:

much snipped...

We've done enough testing of specific claims to have laid that idea to

rest.
There is no underground grain-of-truth resting just below the surface. If

there
were then someone, somewhere would have stumbled on it over the past 30

years
of searching.


Tom,

I agree that there is not much that differs amps during music
listening and using 99.9% of loudspeakers of the market, and standard
DBT testing. But if one wants to find out any putative difference, the
test methodology needs to be the most sensitive around. The
before/after listening tests are far more sensitive that just
comparing two amps A/B, since you are comparing the amp with a bypass
cable (the "before" signal). I've posted the link befo

http://www.sonicdesign.se/amptest.htm

I am not saying that there will be audible differences when comparing
the traditional DBT way, but putting things to "rest" does not mean
that there are differences, explained by physical terms, that can be
judged to be significant different. It will, however, have probably
have little practical meaning for the user. It can also be a
preference to have an amp where the spec are far below the audible
limit thereby it will warrant such a market. (I am not talking about
expensive amps which have poor spec here, but those having high-end
spec and thus in general more expensive.)

T


The wire bypass test is a good idea. In fact, Arny Kreuger's pcabx is precisely
that. But the site's "data" is simply a statement.

But taken in context wouldn't you say that all the cable-swap and switched test
results would tend to show that if it is true as the site claims that if nearly
90% of amplifiers are not straight wires with gain into his simulayed load they
must nearly universally have the same errors.

  #110   Report Post  
Harry Lavo
 
Posts: n/a
Default Does anyone know of this challenge?

"Nousaine" wrote in message
...
"Harry Lavo" wrote:




"Nousaine" wrote in message
news:xHXic.34068$w96.2423643@attbi_s54...
Bromo
wrote:

On 4/24/04 1:03 PM, in article P5xic.20708$aQ6.1263449@attbi_s51,

"Nousaine"
wrote:


snip


It is understood by anyone that if you do not feed the speaker with

enough
power, it won't sound good - too much power, and you will blow it out.
Conventional measurements should indicate if the speaker is likely to

be
suitable, but to think we understand hearing and the processing our

brains
go through to change pressure to sound to make it an end game is pure
arrogance to me!

IMO if there were anything to amp sound that is not readily observable

with
traditional measurements and methods then the Richard Clark Challenge

should
have brought it to light.


Would you please indicate where in Stereophile's set of conventional
measurement the "microphony" test resides that clearly shows microphony

as
the reason tube amps are preferred by many audiophiles, as objectivists

love
to proclaim loudly and often here.


It would seem to me that the frequency response anomalies that come with
high-output impedance amplifiers completely describe any audible

differences in
tubed amplifiers.

As far as the microphony "issue" it seems to me like one you just made up
yourself.


Poppycock (to quote one of your own)!!

I have never mentioned this issue before.. nor do I believe it. But it has
been raised here regularly by certain objectivists....I will not name names
lest I be forced to spend my sleep time looking for the exact quotes, but I
think we know who they are .... or at least they do. So if standard specs
tell it all, I want to know which specs they (and you, since you made the
statement) would have me look at.

Moreover, I and those preferring tubes usually are speaking of good old
push-pull tubed amps with reasonably low output impedances. Not the SET's
that you guys love to whup up on.


  #111   Report Post  
S888Wheel
 
Posts: n/a
Default Does anyone know of this challenge?

From: Stewart Pinkerton
Date: 4/27/2004 9:55 AM Pacific Standard Time
Message-id: Hfwjc.30312$0u6.5306584@attbi_s03

On Mon, 26 Apr 2004 23:54:59 GMT, Bromo wrote:

On 4/26/04 1:34 PM, in article zKbjc.41838$IW1.2009846@attbi_s52, "Stewart
Pinkerton" wrote:

I agree that is a good use of an end user's time and money - but still -

if
people claim to hear a difference, it might be good to do the due

diligence
as a scientific sort to see if there is anything to these claims. Some

have
been made in the past that haven't helped, but some has been made that

did.

That is the exact purpose of the various amp and cable challenges.


The problem is that it is *not* due diligence, but grandstanding rather
loudly !

Real due diligence wopuld involve getting the amplifiers in question and
doing both double blind testing with a variety of speaker systems and a
variety of sonic and electrical measurements.

Not some silly $10k "challenge"


The choice of speaker system is free to the challenger, so what's your
problem? BTW, electrical measurements are irrelevant, we're talking
about *sound* quality here. Once a difference in *sound* has been
established, it's easy enough to pin it down, because it is IME
*always* tied to a gross technical problem, nothing at all subtle!

--

Stewart Pinkerton | Music is Art - Audio is Engineering








Given the fact that you have reported hearing differences between certain
models of amplifiers in your own blind tests, why don't you take the challenge
and collect the 10K?
  #112   Report Post  
 
Posts: n/a
Default Does anyone know of this challenge?

Regarding the test discussed at:

http://www.sonicdesign.se/amptest.htm

"This will force the amplifier to deliver a strongly distorted current,
just like with a normal loudspeaker, in order to deliver a
correct voltage. This is a very hard task for many amplifiers!"

An amp driven into it's nonlinear range can have audible artifacts. What
have we learned that is new from the article? The test, if I'm
understanding it correctly, is driving a fake speaker load and tapping of
the output, providing the above observation. If we introduce some element
into the chain that causes the above, and any amp can in principle be made
to do so, and tap the signal from that element; what have we learned?
Only if in the normal configuration does all the distortions usually
created by current unstability rise above an audible threshold will it be
percieved so to be able to identify it from another amp. Potential to
cause the above is only a concern if a known difficult load is to be used.
This is easy to anticipate and getting an amp with enough current capacity
no problem. To pick an example, if the middle of the line adcom doesn't
do it, larger amps in the line should be purchased instead. It would be
useful for such as the test to be done as part of an amp review, I refuse
to use "audition" for what is done, to see if a particular amp might be
prone to current problems, but the solution is still the same and the
latest wiz bang "night and day" pick of the month is not it.
  #113   Report Post  
Nousaine
 
Posts: n/a
Default Does anyone know of this challenge?

Bromo wrote:



On 4/26/04 1:34 PM, in article zKbjc.41838$IW1.2009846@attbi_s52, "Stewart
Pinkerton" wrote:

I agree that is a good use of an end user's time and money - but still -

if
people claim to hear a difference, it might be good to do the due

diligence
as a scientific sort to see if there is anything to these claims. Some

have
been made in the past that haven't helped, but some has been made that

did.

That is the exact purpose of the various amp and cable challenges.


The problem is that it is *not* due diligence, but grandstanding rather
loudly !

Real due diligence wopuld involve getting the amplifiers in question and
doing both double blind testing with a variety of speaker systems and a
variety of sonic and electrical measurements.

Not some silly $10k "challenge"


As if that had not already been done. By May of 1990 over 2 dozen
bias-controlled listening tests had been published, none of which showed that
any amplifier that had matched levels and frequency response had any "sound" of
its own.

Mr Clark, like other professionals such as me, has been constantly bombarded
with sometimes simply misguided but often wild shouting about the "sound" of
amplifiers which have never been verified. This was his way of encouaging those
who insist on amp-sound to cough up some evidence, prove their case or get out
of the way.

I think its clever but ultimately self-defeating because keeping the faith
depends heavily on refusing to supply evidence and to keep 'debating' the issue
and challenges no matter how fair or how possibly rewarding are unlikely to be
met.
This is because keeping the story or any Urban Legend "alive" depends on a lack
of scientific investigation (no positive evidence) and diversion (You haven't
proven that amplifiers don't sound different and Your Tools Aren't Good
Enough.)

So sure, Clark doesn't get many applicants because deep down inside no
Subjectvists is sure enough of himself to step up to the plate. It's much more
comforting to argue than to prove your case.

SO instead of simply proving his case Mr Lavo suggests a long complicated
experiment which if it doesn't support his hypothesis (supply results identical
to those gathered under conditions known to encourage common human bias
mechanisms) will be proclaimed to have disqualified all extant evidence.

Its a clever tactic for 2 reasons. First its long, expensive and unlikely to
ever be coinducted (certainly not by him) and if it is it has a pre-determined
outcome. IOW it a self-fulfilling prophecy. Oh yes, I forgot it keeps the
"debate" going.
  #114   Report Post  
Thomas A
 
Posts: n/a
Default Does anyone know of this challenge?

(Nousaine) wrote in message news:_0Bjc.31128$0u6.5483536@attbi_s03...
(Thomas A) wrote:

much snipped...

We've done enough testing of specific claims to have laid that idea to

rest.
There is no underground grain-of-truth resting just below the surface. If

there
were then someone, somewhere would have stumbled on it over the past 30

years
of searching.


Tom,

I agree that there is not much that differs amps during music
listening and using 99.9% of loudspeakers of the market, and standard
DBT testing. But if one wants to find out any putative difference, the
test methodology needs to be the most sensitive around. The
before/after listening tests are far more sensitive that just
comparing two amps A/B, since you are comparing the amp with a bypass
cable (the "before" signal). I've posted the link befo

http://www.sonicdesign.se/amptest.htm

I am not saying that there will be audible differences when comparing
the traditional DBT way, but putting things to "rest" does not mean
that there are differences, explained by physical terms, that can be
judged to be significant different. It will, however, have probably
have little practical meaning for the user. It can also be a
preference to have an amp where the spec are far below the audible
limit thereby it will warrant such a market. (I am not talking about
expensive amps which have poor spec here, but those having high-end
spec and thus in general more expensive.)

T


The wire bypass test is a good idea. In fact, Arny Kreuger's pcabx is precisely
that. But the site's "data" is simply a statement.

But taken in context wouldn't you say that all the cable-swap and switched test
results would tend to show that if it is true as the site claims that if nearly
90% of amplifiers are not straight wires with gain into his simulayed load they
must nearly universally have the same errors.


Tom,

I don't think they are saying that every amp has the same errors, but
they can probably be divided into a few "groups". I've not read all
the different tests that have been conducted during the years, but
usually, the amps coming up to be transparent (or very close) are e.g.
NAD 208 THX and Rotel RB 1090.

The recommended list of equipment is he

http://www.lts.a.se/teknik/rekommenderat.html

Although it is in Swedish it is probably not difficult to understand
which components that are "recommended".

T
  #115   Report Post  
Stewart Pinkerton
 
Posts: n/a
Default Does anyone know of this challenge?

On 27 Apr 2004 23:24:07 GMT, "Harry Lavo" wrote:

"Nousaine" wrote in message
...


As far as the microphony "issue" it seems to me like one you just made up
yourself.


Poppycock (to quote one of your own)!!

I have never mentioned this issue before.. nor do I believe it. But it has
been raised here regularly by certain objectivists....I will not name names
lest I be forced to spend my sleep time looking for the exact quotes, but I
think we know who they are .... or at least they do.


I am one of them. I have heard definite microphony effects in SET
amps - easily proved by locating the amps in my study (from where I'm
typing this), which is through a brick wall from the listening room,
but has a baffled cable duct for 'PC sound' and separates the amp
from the acoustic impact of the speakers. The traditional placing of
monobloc SET amps behind the speakers turns out to be a *bad* idea!

The same is even more true of tubed phono stages.

Moreover, I and those preferring tubes usually are speaking of good old
push-pull tubed amps with reasonably low output impedances. Not the SET's
that you guys love to whup up on.


Indeed, I'd agree that a top-class PP tube amp like the ARC VT100 or
C-J Premier Eight is indistinguishable from any good SS amp, which is
kinda interesting, given all the claims for 'tube magic', which seems
to go away as the tube amp gets better.......................
--

Stewart Pinkerton | Music is Art - Audio is Engineering



  #117   Report Post  
Thomas A
 
Posts: n/a
Default Does anyone know of this challenge?

wrote in message ...
Regarding the test discussed at:

http://www.sonicdesign.se/amptest.htm

"This will force the amplifier to deliver a strongly distorted current,
just like with a normal loudspeaker, in order to deliver a
correct voltage. This is a very hard task for many amplifiers!"

An amp driven into it's nonlinear range can have audible artifacts. What
have we learned that is new from the article? The test, if I'm
understanding it correctly, is driving a fake speaker load and tapping of
the output, providing the above observation. If we introduce some element
into the chain that causes the above, and any amp can in principle be made
to do so, and tap the signal from that element; what have we learned?
Only if in the normal configuration does all the distortions usually
created by current unstability rise above an audible threshold will it be
percieved so to be able to identify it from another amp. Potential to
cause the above is only a concern if a known difficult load is to be used.
This is easy to anticipate and getting an amp with enough current capacity
no problem. To pick an example, if the middle of the line adcom doesn't
do it, larger amps in the line should be purchased instead. It would be
useful for such as the test to be done as part of an amp review, I refuse
to use "audition" for what is done, to see if a particular amp might be
prone to current problems, but the solution is still the same and the
latest wiz bang "night and day" pick of the month is not it.


Note that this not a test, but a test method. All tests made using
this method is published elsewhere and, unfortunately, in Swedish.
Except for compression artefacts at high outputs, there are frequency
response deviations that in some cases shows up as different in the
blind tests. Also, the reviewer is free to set the criteria for a
"recommended amp", e.g. "it should be able to recreate the signal in
99.9% of the speakers in the market with no or little compression of
musc playing realistic levels" (which can be quite high if you want to
simulate the SPL of a drum set . As stated in their recommendation
of the NAD 208 THX amp:

"Able to reproduce signals with no audible artefacts up to 250W, and
with small audible artefacts up to 600 W"

Now, what new can be gained by such a before/after test? Well, with
respect to frequency response deviations, with amp with similar roll
off in the low en (e.g. -3 dB at 7 Hz) may not be different in a
standard A/B test, but when compared to a cable only, it might. So the
advantage of a before/after listening test is that it's more sensitive
for colorations. This goes for all types of possible audible
colorations. So my point is that if one really wants to find out
audible (or tactile) differences, the most sensitive test method must
be used.

Thomas
  #118   Report Post  
Harry Lavo
 
Posts: n/a
Default Does anyone know of this challenge?

"Stewart Pinkerton" wrote in message
news:w8Rjc.6132$lz5.814689@attbi_s53...
On 27 Apr 2004 23:24:07 GMT, "Harry Lavo" wrote:

"Nousaine" wrote in message
...


As far as the microphony "issue" it seems to me like one you just made

up
yourself.


Poppycock (to quote one of your own)!!

I have never mentioned this issue before.. nor do I believe it. But it

has
been raised here regularly by certain objectivists....I will not name

names
lest I be forced to spend my sleep time looking for the exact quotes, but

I
think we know who they are .... or at least they do.


I am one of them. I have heard definite microphony effects in SET
amps - easily proved by locating the amps in my study (from where I'm
typing this), which is through a brick wall from the listening room,
but has a baffled cable duct for 'PC sound' and separates the amp
from the acoustic impact of the speakers. The traditional placing of
monobloc SET amps behind the speakers turns out to be a *bad* idea!

The same is even more true of tubed phono stages.

Moreover, I and those preferring tubes usually are speaking of good old
push-pull tubed amps with reasonably low output impedances. Not the

SET's
that you guys love to whup up on.


Indeed, I'd agree that a top-class PP tube amp like the ARC VT100 or
C-J Premier Eight is indistinguishable from any good SS amp, which is
kinda interesting, given all the claims for 'tube magic', which seems
to go away as the tube amp gets better.......................


And what audiophiles do you know who have bought ARC VT100 or C-J Premier
Eights (among the most popular of mainstream tube amps) that thought they
lacked "tube magic"?
  #119   Report Post  
Nousaine
 
Posts: n/a
Default Does anyone know of this challenge?

(Thomas A) wrote:

(Nousaine) wrote in message
news:_0Bjc.31128$0u6.5483536@attbi_s03...
(Thomas A) wrote:

much snipped...

We've done enough testing of specific claims to have laid that idea to

rest.
There is no underground grain-of-truth resting just below the surface.

If
there
were then someone, somewhere would have stumbled on it over the past 30

years
of searching.

Tom,

I agree that there is not much that differs amps during music
listening and using 99.9% of loudspeakers of the market, and standard
DBT testing. But if one wants to find out any putative difference, the
test methodology needs to be the most sensitive around. The
before/after listening tests are far more sensitive that just
comparing two amps A/B, since you are comparing the amp with a bypass
cable (the "before" signal). I've posted the link befo

http://www.sonicdesign.se/amptest.htm

I am not saying that there will be audible differences when comparing
the traditional DBT way, but putting things to "rest" does not mean
that there are differences, explained by physical terms, that can be
judged to be significant different. It will, however, have probably
have little practical meaning for the user. It can also be a
preference to have an amp where the spec are far below the audible
limit thereby it will warrant such a market. (I am not talking about
expensive amps which have poor spec here, but those having high-end
spec and thus in general more expensive.)

T


The wire bypass test is a good idea. In fact, Arny Kreuger's pcabx is

precisely
that. But the site's "data" is simply a statement.

But taken in context wouldn't you say that all the cable-swap and switched

test
results would tend to show that if it is true as the site claims that if

nearly
90% of amplifiers are not straight wires with gain into his simulayed load

they
must nearly universally have the same errors.


Tom,

I don't think they are saying that every amp has the same errors, but
they can probably be divided into a few "groups". I've not read all
the different tests that have been conducted during the years, but
usually, the amps coming up to be transparent (or very close) are e.g.
NAD 208 THX and Rotel RB 1090.

The recommended list of equipment is he

http://www.lts.a.se/teknik/rekommenderat.html

Although it is in Swedish it is probably not difficult to understand
which components that are "recommended".

T


Sorry I wasn't a bit more clear. If, as this sire claimed, 8 of 9 amplifiers
could be distinguished from a straight wire when their output was played
through a 2nd amplifier then amplifiers 'different' sounding than a piece of
wire are common.

However, there have been a couple dozen bias-controlled listening tests of
amplifiers which have only found amplifiers with a lack of competence
(frequency response, overload or other operating errors) to sound different
from one another.

So putting these two data set together I would think that all those amplifiers
that sound different from a piece of wire (90%) but do not show up as being
different sounding from each other in other tests must have errors with enough
similarity that they sound like each other even if they don't sound identical
to a piece of wire.

  #120   Report Post  
Bromo
 
Posts: n/a
Default Does anyone know of this challenge?

On 4/28/04 12:41 PM, in article w8Rjc.6132$lz5.814689@attbi_s53, "Stewart
Pinkerton" wrote:

Moreover, I and those preferring tubes usually are speaking of good old
push-pull tubed amps with reasonably low output impedances. Not the SET's
that you guys love to whup up on.


Indeed, I'd agree that a top-class PP tube amp like the ARC VT100 or
C-J Premier Eight is indistinguishable from any good SS amp, which is
kinda interesting, given all the claims for 'tube magic', which seems
to go away as the tube amp gets better.......................


What about the slew rate of a tube - isn't it slower than most non-switch
mode solid state?

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