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Amplifier Sound


Deang
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I like what the author said, all amps should sound the same but, clipping, input voltage, ect all make a difference. I never use the term like night and day difference, but there are subtle differences.

Not sure thats what he meant. Should sound the same as in if they are built to perform the same they would. So in theory they should but in reality they don't. If they sound different to me its night and day. Subtle would be a monster understatement in my comparison (its not even close). But you also said the rf-7 was not much different to you than the icon speaker so i could see why night and day may seem like overkill from your point of view. :)

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My long standing observation is that the K-Horn LS, and Belle put out 104 db at one watt (nominal) at one meter for one speaker and:

60 dB down from that is 44 dB which is pretty quiet. One scale I see on the Internet puts 40 dB as a quiet library.

It is not too farfetched to say that some of our listening is at 44 dB.

But to make that 44 dB we need only 1 microwatt from the amp, if my calculations are correct.

Were are the measured distortion levels on amps running 1 microwatt output in comparison?

If 44 dB is too low to account for our normal listening levels, I'll settle for 1 milliwatt which is 30 dB down from 104 dB or 74 dB. That is above normal conversation and less than a vacuum cleaner at 1 meter -- you can stuff like this on the Internet.

We can put in an extra 3 dB for two speakers and maybe knock it down 6 dB or more for distance. But we are still in these ballpark figures.

WMcD

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Every amp I have tried with my Fortes has sounded different. If you can't hear differences between different amplifiers, then - unless the amps are very similar - either your speakers or your ears are not very good. By "ears", I mean either their physical capabilities or your brain's ability to discern what you are hearing.

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I like what the author said, all amps should sound the same but, clipping, input voltage, ect all make a difference. I never use the term like night and day difference, but there are subtle differences.

Are those subtle differences heard if the amps are working way below
clipping, as they would be with Klipschorns with most music in most
rooms? Back in the earlier days of solid state I think I heard differences
between solid state and tube models, but I'm not sure I do with modern
amps through very efficient speakers. The turning point happened in
the mid-1980s when I heard ABC blind comparisons between three good
amps. The first two or three times through the sales guy and I were
pretty sure we heard differences, but later we fooled ourselves
repeatedly and misidentified the amp playing at any given time. Since
then, such comparisons gradually went out of style, and I haven't heard
any recently.

Yes, I know the alleged problems with AB
comparisons, in that perception may be different when listening to make
judgements v.s. listening in a relaxed atmosphere for pleasure, but those
could be handled with a factorial design with switched comparisons of
short term auditions of A & B v.s. long term, letting the music
through a certain amp you are blind to wash over you for a few days v.s.
the same with another amp, through many trials, over a period of weeks,
with order effect and carry-over effect controlled for, but that takes
much more effort and dedication than most listening tests.

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ot sure thats what he meant. Should sound the same as in if they are built to perform the same they would. So in theory they should but in reality they don't. If they sound different to me its night and day. Subtle would be a monster understatement in my comparison (its not even close). But you also said the rf-7 was not much different to you than the icon speaker so i could see why night and day may seem like overkill from your point of view. :)

reference_head, my statement of the 7's and Icon V speakers was in a combined system due to the EQ'ing from the preamp. It was not an A/B comparison. I have stated many times that it is my opinion that all amps don't sound the same. I have also stated in the past that the SC avr's have a timber matching feature which is why I most likely do not have a problem integrating speakers from different serie/lines. Maybe it is just my ears. All of our listening experiences are veiwed from our own perspective which is why the use of subjective terms comes up so often. They are not right or wrong, just one person's/people experience [8-|] .

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ot sure thats what he meant. Should sound the same as in if they are built to perform the same they would. So in theory they should but in reality they don't. If they sound different to me its night and day. Subtle would be a monster understatement in my comparison (its not even close). But you also said the rf-7 was not much different to you than the icon speaker so i could see why night and day may seem like overkill from your point of view. :)

reference_head, my statement of the 7's and Icon V speakers was in a combined system due to the EQ'ing from the preamp. It was not an A/B comparison. I have stated many times that it is my opinion that all amps don't sound the same. I have also stated in the past that the SC avr's have a timber matching feature which is why I most likely do not have a problem integrating speakers from different serie/lines. Maybe it is just my ears. All of our listening experiences are veiwed from our own perspective which is why the use of subjective terms comes up so often. They are not right or wrong, just one person's/people experience Geeked .

I think we are agreeing from each others point of view and it just comes out different. [;)]

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"The fact that there are differences is obvious. The degree of difference and why there are differences is not." -- considering his general position on things, I was impressed with the admission. It's nice to see an audio related post from you Mark, it's been a while.

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Mark,

Thanks for your take on this. and thanks for typing slow because i can't read fast. ;-)

One thing that came to mind, reading this guy talking about how expectations about how a given amplifier should sound, was something you posted back in the early JM days. You mentioned a comparison you'd set up some years ago where the same amplifier was installed in two different cases. One had quite a heavy face plate and the other sort of svelt. The listeners, not knowing that the amps were identical had substantially different evaluations of the sound, noting that the heavier cased amplifier was more authority, power bass and even balsy.

knowing the power of subjective expectations presents a challenge in evaluating just about anything except magic rocks. no evaluation needed for a sure thing!

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Guest David H

One thing that came to mind, reading this guy talking about how expectations about how a given amplifier should sound, was something you posted back in the early JM days. You mentioned a comparison you'd set up some years ago where the same amplifier was installed in two different cases. One had quite a heavy face plate and the other sort of svelt. The listeners, not knowing that the amps were identical had substantially different evaluations of the sound, noting that the heavier cased amplifier was more authority, power bass and even balsy.

Gives a bit of merit to the blind test. I wonder if the audience would have heard a difference if they could not see them.

Dave

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I think it is a mistake to turn an artistic endeavor into data-driven codified experience. Music itself is not this way, so making music in your living room ought to be as free-wheeling as the other end of the process.

HALLELUJAH

Now lets all go and get some [pi] &

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A person doesn't
"think" he likes Twain better than Tolstoy, he simply does.
A person doesn't think they like Miro over Picasso, they simply do.
And people don't think they like a SS amp better than a tube, they
simply do.

A HiFi set playing a record or CD is never, under any
circumstance now or in the future, going to flawlessly "reproduce"
the sounds of the musical event that took place at the time of
recording.


.... and if it did, we wouldn't know it. What we are looking for is faithfulness to the imagined original, or a sound that pleases us, or both.

We may like Twain or Tolstoy, as you say. The trouble is that they both vary. Some of Twain and some of Tolstoy I consider superb, and some pedestrian, and my view of my reading experience is not usually changed by what others think. My liking for a given HiFi component varies with the program material. I have Khorns because they often pleased me, particularly with low distortion recordings with great dynamic contrasts ... but sometimes I long to hear one of my CDs on another speaker, e.g., an old Bozak three way. This was immediately clear when I ABd Khorns with other speakers, such as the JBL Paragon (close), and the B&W 801 F (very different). I favored the Khorn about 60% of the time over the Paragon, and about 90% of the time over the B&W. It would be lovely, but ridiculous, to have all three (or others) splayed across my listening room. I knew a guy who preferred Bose 901s for some of his listening, but insisted on using his Altec A7s to playback recordings of his guitar work, because they sounded both better and more real to him with guitar.

My "artistic" experience occasionally involves using tone controls, sometimes in addition to Audyssey. I adjust for preference, but preference often coincides with my fallible memory of the sound of the several orchestras and a couple of bands I played in, which may boil down to faithfulness to the imagined original.

As I have said before, the differences between amps are much less important to me than the differences between recordings (gargantuan and unpredictable), rooms, and speakers. Most of us can't afford several amps in the same room. BUT, if someday there is a set of tests that could reliably delineate a relevant and comprehensive set of differences between high quality amplifiers, and my choices in blind perceptual choice experiments were also put in a data base and analyzed, the tests might predict my amplifer preferences -- if any --- with given CDs, but it would require another set of free wheeling blind choices to predict another individual's preferences in amplifiers with those CDs.


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The 800 pound gorilla in the room is this... an amplifier cannot make a sound on it's own. It requires a source connected to the input and a transducer connected to it's output in order to do that. Testing an audio amplifier with a resistive load absolutely will not give one an idea of how it will sound. Using a "simulated loudspeaker load" consisting of resistors, coils, and capacitors is not the answer either because a moving loudspeaker generates back EMF which can affect the amplifier.There are thousands of models of speakers out there, each with different impedance curves, drive requirements, frequency and phase responses, sensitivities, et al. If a loudspeaker is to be connected for testing purposes, which loudspeaker should it be?

If the amplifier's input impedance is too low it can affect the operation of the source, changing the signal before the amplifier amplifies it. And what sort of test signal should be used? A simple sine wave is no good as far as determining how an amplifier will sound, as music does not consist of one single frequency tone at a steady level.

I don't want to imply that amplifier testing with sine waves and resistive loads is of no value at all. Those types of signals and loads are quite useful in exposing nonlinearities. If the amplifier doesn't pass such a test it will not do better with a complex input signal or a complex load. Sine wave and resistive load testing is also valuable for production line quality control.

PWK did some amplifier tests that he published in a Dope From Hope, Vol. 16 No. 8. He tested an amplifier with a resistive load and then with a Heresy as a load. When testing for TIM distortion with a resistive load the TIM level was -76 dB. With the Heresy load there was no TIMD visible on the graph. That's just one example of how the load can affect the output of an amplifier.

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My long standing observation is that the K-Horn LS, and Belle put out 104 db at one watt (nominal) at one meter for one speaker and:

60 dB down from that is 44 dB which is pretty quiet. One scale I see on the Internet puts 40 dB as a quiet library.

It is not too farfetched to say that some of our listening is at 44 dB.

But to make that 44 dB we need only 1 microwatt from the amp, if my calculations are correct.

Were are the measured distortion levels on amps running 1 microwatt output in comparison?

If 44 dB is too low to account for our normal listening levels, I'll settle for 1 milliwatt which is 30 dB down from 104 dB or 74 dB. That is above normal conversation and less than a vacuum cleaner at 1 meter -- you can stuff like this on the Internet.

We can put in an extra 3 dB for two speakers and maybe knock it down 6 dB or more for distance. But we are still in these ballpark figures.

WMcD

Or we could just take an oscilloscope and measure the voltage.....your analogy isn't taking into account crest factor of the source material, and the fact that the waveform is much differently shaped with a multi tone signal. Amplifiers don't have a perfectly flat distortion response either - the clipping behaviors can start as much as 10dB before the true maximum output voltage.

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