[William Noble]

wrote in message ...
it really is not true that all properly designed amps sound the same. it
is
true that you can hear a 3db increase in power pretty clearly up to very
high power levels (400 watts or more per channel). The power amp, in my
opinion makes less difference overall than the preamp, but both affect the
sound. you need to decide on budget, and on what kind of sound you like.
and you need to listen

This is a popular view but in listening alone tests can not be confirmed.

A 3db difference is one of level adjustment. If it occurs otherwise it is
not a properly designed amp.

The term "properly" is always relative to its design parameters as to
highest db demand in a given context. Two amps which at moderate normal
listening levels which present no difference in sound will at much higher
levels sound different as one goes into clipping and other distortion
modes as parameters are exceeded.

1. there is no "level adjustment" on any amplifier I have ever seen, read
about, or imagined that allows you to click a "level adjustment" and add 3dB
to output power.

2. There is a huge difference between volume and power requirements, and the
power needs depend on all the stuff peter said plus the spectral composition
of your music

3. slew rate is a critical and generally unreported parameter

4.in my experience, two amplifiers with 3db different max power (say 300
watts per channel and 600 watts per channel) driving the same speakers, with
the same preamps, cables, and source material, in the same room with the
same listers, and made by the same manufacture, will be audibly different,
with the higher power amplifier ALWAYS being prefered, even when played at a
low enough volume that you can wisper and be heard over the sound.

5. I have done tests where I lined up a pile of power amps, for example, a
10 watt Leak, a 35 watt Fischer, a 60 watt dynaco, a 350 watt kenwood -
using the speakers I had at the time (AR-3) and the music I liked at the
time (don't remember what I used), there was no question that the quality of
the resultant sound improved with power - the low end went from muddy to
crisp. A 700 watt amp that I tried was one notch better, but beyond my
budget. I'm not going to debate this, you may hear differently, this is
what I hear, at the same very soft volume level.

6. "properly" designed amplifiers is a completely undefined term, and there
is no way to define it. You can write specifications, as voluminous as you
want, and most folks will easily hear differences between amplfiers that
conform to all your specs, whatever you choose to write in them. So, when
the OP said "properly designed", he/she basically asked a non-question.
Once you crawl out of the "consumer grade" stuff, it is your personal
preference for a particular coloration that will help you decide which unit
you like.

[[email protected]]

5. I have done tests where I lined up a pile of power amps, for example, a
10 watt Leak, a 35 watt Fischer, a 60 watt dynaco, a 350 watt kenwood -
using the speakers I had at the time (AR-3) and the music I liked at the
time (don't remember what I used), there was no question that the quality of
the resultant sound improved with power - the low end went from muddy to
crisp. A 700 watt amp that I tried was one notch better, but beyond my
budget. I'm not going to debate this, you may hear differently, this is
what I hear, at the same very soft volume level.

And there is no debate that the experience mentioned is rife with well
known and universally accepted problems unless done under controlled
conditions, especially done blind.

What those being tested using listening alone can show does not confirm
differences such as you suggest.

It is easily accepted that you report accurately what you heard. The
question is did that difference exist in the signal as it reached the ears
or was it a product of the perception process of sound in the brain.

This is where controlled testing comes in so as to remove as much as
possible perception alone effects not existing in the signal.

[jwvm]

On Oct 13, 9:19*am, "William Noble" wrote:

snip

3. slew rate is a critical and generally unreported parameter

This is certainly true but modern designs provide sufficient slew
rate. If slew rate is a problem, an amplifier will exhibit high
distortion levels.


4.in my experience, two amplifiers with 3db different max power (say 300
watts per channel and 600 watts per channel) driving the same speakers, with
the same preamps, cables, and source material, in the same room with the
same listers, and made by the same manufacture, will be audibly different,
with the higher power amplifier ALWAYS being prefered, even when played at a
low enough volume that you can wisper and be heard over the sound.

This is a truly remarkable claim. As long as an amplifier is operated
within its design specifications, it should not have audible
distortion. Can you cite any objective studies that support this?


5. I have done tests where I lined up a pile of power amps, for example, a
10 watt Leak, a 35 watt Fischer, a 60 watt dynaco, a 350 watt kenwood -
using the speakers I had at the time (AR-3) and the music I liked at the
time (don't remember what I used), there was no question that the quality of
the resultant sound improved with power - the low end went from muddy to
crisp. *A 700 watt amp that I tried was one notch better, but beyond my
budget. *I'm not going to debate this, you may hear differently, this is
what I hear, at the same very soft volume level.

These amplifers have very different designs so it is really a stretch
to base perceived differences on power output. Presumably the tests
were all done sighted which can easily result in biased results. Power
output is no predictor of sound quality assuming that an amplifier is
not pushed beyond its limits.


6. "properly" designed amplifiers is a completely undefined term, and there
is no way to define it. *You can write specifications, as voluminous as you
want, and most folks will easily hear differences between amplfiers that
conform to all your specs, whatever you choose to write in them. So, when
the OP said "properly designed", he/she basically asked a non-question.
Once you crawl out of the "consumer grade" stuff, it is your personal
preference for a particular coloration that will help you decide which unit
you like.

"Properly designed" certainly has a meaning in an engineering sense.
The designers followed modern design techniques and selected
components of sufficient quality to achieve state-of-the-art
performance. Amplifiers with uniform frequency response and low
distortion levels will produce virtually identical output waveforms
when operated within their design specifications. Why would they not
sound the same?

[Sonnova]

On Mon, 13 Oct 2008 06:19:13 -0700, William Noble wrote
(in article ):

wrote in message ...
it really is not true that all properly designed amps sound the same. it
is
true that you can hear a 3db increase in power pretty clearly up to very
high power levels (400 watts or more per channel). The power amp, in my
opinion makes less difference overall than the preamp, but both affect the
sound. you need to decide on budget, and on what kind of sound you like.
and you need to listen

This is a popular view but in listening alone tests can not be confirmed.

A 3db difference is one of level adjustment. If it occurs otherwise it is
not a properly designed amp.

The term "properly" is always relative to its design parameters as to
highest db demand in a given context. Two amps which at moderate normal
listening levels which present no difference in sound will at much higher
levels sound different as one goes into clipping and other distortion
modes as parameters are exceeded.

1. there is no "level adjustment" on any amplifier I have ever seen, read
about, or imagined that allows you to click a "level adjustment" and add 3dB
to output power.

2. There is a huge difference between volume and power requirements, and the
power needs depend on all the stuff peter said plus the spectral composition
of your music

3. slew rate is a critical and generally unreported parameter

4.in my experience, two amplifiers with 3db different max power (say 300
watts per channel and 600 watts per channel) driving the same speakers, with
the same preamps, cables, and source material, in the same room with the
same listers, and made by the same manufacture, will be audibly different,
with the higher power amplifier ALWAYS being prefered, even when played at a
low enough volume that you can wisper and be heard over the sound.

5. I have done tests where I lined up a pile of power amps, for example, a
10 watt Leak, a 35 watt Fischer, a 60 watt dynaco, a 350 watt kenwood -
using the speakers I had at the time (AR-3) and the music I liked at the
time (don't remember what I used), there was no question that the quality of
the resultant sound improved with power - the low end went from muddy to
crisp. A 700 watt amp that I tried was one notch better, but beyond my
budget. I'm not going to debate this, you may hear differently, this is
what I hear, at the same very soft volume level.

Using the amps that you used, I suspect that the Leak, probably the Fisher,
and perhaps the Dynaco (unless it was a ST120 rather than a Mk.III, you don't
say) were tube (valve) amps. if so, the bass quality difference has as much
to do with output transformers in the tube gear vs solid-state (the Kenwood
and perhaps the the Dynaco - if its a solid-state amp), as it has to do with
power.

6. "properly" designed amplifiers is a completely undefined term, and there
is no way to define it. You can write specifications, as voluminous as you
want, and most folks will easily hear differences between amplfiers that
conform to all your specs, whatever you choose to write in them. So, when
the OP said "properly designed", he/she basically asked a non-question.
Once you crawl out of the "consumer grade" stuff, it is your personal
preference for a particular coloration that will help you decide which unit
you like.

Modern, solid-state amps sound practically identical, irrespective of cost.
What differences that their might be are truly subtle and minute. While some
audiophiles are willing to pay megabucks for amps that sound so close to
their much cheaper cousins, that the differences are more imagined than
actually experienced, for all practical purposes, the differences (if
discernible at all) disappear into total unimportance after a few minutes of
listening. The important part of choosing an amplifier these days is to get
one with enough power for your particular speakers and your listening
preferences with regard to playback level.

[Steven Sullivan]

William Noble wrote:
5. I have done tests where I lined up a pile of power amps, for example, a
10 watt Leak, a 35 watt Fischer, a 60 watt dynaco, a 350 watt kenwood -
using the speakers I had at the time (AR-3) and the music I liked at the
time (don't remember what I used), there was no question that the quality of
the resultant sound improved with power - the low end went from muddy to
crisp. A 700 watt amp that I tried was one notch better, but beyond my
budget. I'm not going to debate this, you may hear differently, this is
what I hear, at the same very soft volume level.


If output levels aren't objectively matched to within a fraction of a dB on all channels, the
test is seriously flawed; if comparisons are done 'sighted' and not blind, the test is
seriosly flawed. Yours appears to be flawed in both dimensions.

To debate THOSE points, would be to debate the body of psychoacoustics literature.

6. "properly" designed amplifiers is a completely undefined term, and there
is no way to define it. You can write specifications, as voluminous as you
want, and most folks will easily hear differences between amplfiers that
conform to all your specs, whatever you choose to write in them.

Yes, but that is a well-known psychological phenomenon, not necessarily reflective of real
sonic difference between the devices. The mere fact that 'most folks' will claim to hear
differences, does not rise even marginally to the standard of proof-of-claim demanded by
science.

Again, there is a very good reason why when audible difference is studies scientifically,
double-blind protocols are used.


--
-S
A wise man, therefore, proportions his belief to the evidence. -- David Hume, "On Miracles"
(1748)

[Arny Krueger]

"William Noble" wrote in message


3. slew rate is a critical and generally unreported
parameter

In fact the actual requirements for power amplifier slew rate are generally
minimal, and any reasonably well-designed amplifier will have more than
enough of this kind of capability. For example, a typical CD player with a
nominal 2 volt RMS output capability cannot put out a signal with more
slewing than a 22.05 KHz sine wave with a peak-to-peak amplitude of about
5.6564 volts. Maximum slew rate is 124,723.62 volts per second or 0.124
volts per microsecond. A 200 wpc power amp would amplify this signal by 20
for a maximum slew rate of about 2.5 volts per microsecond.

4.in my experience, two amplifiers with dab different max
power (say 300 watts per channel and 600 watts per
channel) driving the same speakers, with the same
preamps, cables, and source material, in the same room
with the same liters, and made by the same manufacture,
will be audibly different,

A result that lacks a technically reasonable physical explanation.

with the higher power
amplifier ALWAYS being preferred, even when played at a
low enough volume that you can whisper and be heard over
the sound.

Been there, done that, and never heard a difference.

6. "properly" designed amplifiers is a completely
undefined term, and there is no way to define it.

Properly designed amplifiers lack audible coloration when used within their
ratings.

You can write specifications, as voluminous as you want,

Written claims are mere abstractions of actual amplifier performance.
Specifications represent the minimal level of permissible performance, and
do not guarantee or even reliably infer that the actual performance of
equipment with identical specifications will be similar.

and most folks will easily hear differences between amplifiers
that conform to all your specs, whatever you choose to
write in them.

Yet another baseless claim that has been rebutted by numerous amplifier
listening tests over the past 30 or more years.