My definition of 'no appreciable difference between input and output signals' was: there is no audible difference between input and output signal. Logically, amplifiers with that attribute therefore sound the same. How could it be otherwise?
jan didden
Jan,
How do we determine "no audible difference between input and output signal" for an amplifier? It is doable for cables, possibly even for preamp's and maybe DAC's, but amplifiers?
What is your "reference" for the "input signal" that allows audible comparison to allows to conclude "no audible difference" in a manner that is fair and sensible?
Yes, they would be the same. However you have a major issue to explain how you can quantify said attributes?
Ciao T
How do we determine "no audible difference between input and output signal" for an amplifier? It is doable for cables, possibly even for preamp's and maybe DAC's, but amplifiers?
What is your "reference" for the "input signal" that allows audible comparison to allows to conclude "no audible difference" in a manner that is fair and sensible?
Yes, they would be the same. However you have a major issue to explain how you can quantify said attributes?
Ciao T
Yes that's a major pita. But, as I said, engineers are good in solving clearly defined problems
. This one is like bootstrapping.An idea: how about using a 'good' headphone, switching between input and output (suitably attenuated), if the source can handle the load? The headphone doesn't need to be ruler flat or something because you listen for differences. Even an amplifed headphone could work, as headphone amps are probably an order of magnitude more accurate than power amps.
Question: since we only listen to minute differences, we need a method to show minute differences, not necessarily show the differences exactly as they are. So, even a power amp could be used. Take the example that you have an amp that has 1% THD, and you want to know if that is audible. You take another power amp, with that same 1% THD, and you switch it between the input and the attenuated output of the DUT. How important is that 1% THD of the amp you use for listening? Is it important at all, or irrelevant?
What does the gathered intelligence out there feel about that?
jan didden
I've often used headphones thru an attenuation network and dummy load to listen for differences. It's not a bad technique. But the dummy load in my case was always purely resistive, so that's not ideal. And I do miss some stuff on headphones that I hear with speakers - spacial stuff, mostly.
Jan,
Hold on, you presented your assertion as observed fact. I can think of a few possible solution, however this is not what I asked, what I asked is what test setup YOU used to establish "no audible difference between input and output" for "best amplifiers"?
I really need to know the experimental setup you used to establish your results to know if I should give credence to the claims you made.
Ciao T
Yes that's a major pita. But, as I said, engineers are good in solving clearly defined problems
An idea: how about using a 'good' headphone, switching between input and output (suitably attenuated), if the source can handle the load?
Hold on, you presented your assertion as observed fact. I can think of a few possible solution, however this is not what I asked, what I asked is what test setup YOU used to establish "no audible difference between input and output" for "best amplifiers"?
I really need to know the experimental setup you used to establish your results to know if I should give credence to the claims you made.
Ciao T
Yes ideally you'd use a real-world load, a speaker or a dummy speaker load.
About the spacial things, do you think we could have the situation that two amps have a different spacial rendering, yet sound the same on the headphone?
jan didden
I tired to build a dummy load out of a speaker that I could not hear, but that didn't work. Not sure that a passive L,R,C network would be as good a dummy - but it should be better than just a resistor..
Yes, I think that two amps could have different spacial renderings and "I" wouldn't hear it on headphones. But that's me and my ears.
Yes, I think that two amps could have different spacial renderings and "I" wouldn't hear it on headphones. But that's me and my ears.
There's one test I use which no loudspeaker has passed- but it consistently works on headphones. "For a Thousand Mothers" on Jethro Tull's Stand Up. The main section of the song (in E) ends, then a reprise in D begins. In the beginning of the reprise, there's a little drum and cymbal figure- with excellent headphones, you can make out a sound like a champagne cork in the second part of that figure, right as Clive Bunker moves from cymbals to tom. Never been able to hear that on loudspeakers.
Ok,
My space is big enough I can load two amplifiers with loudspeakers and look at the difference. When I tried this after balancing the output level, several issues show up.
The gain of the amplifiers does change a bit as they heat up and cool down. Even using two channels of the same stereo amplifier, there are artifacts that show up. How do you judge these?
I can't imagine two different amplifiers not having even more artifacts than two of what should be the same.
That is how I got to the resistor vs the loudspeaker load test. The amplifiers I am familiar with do not drive resistors and loudspeakers the same. It is waaay to early for me to present the results of this bit of playing around.
My space is big enough I can load two amplifiers with loudspeakers and look at the difference. When I tried this after balancing the output level, several issues show up.
The gain of the amplifiers does change a bit as they heat up and cool down. Even using two channels of the same stereo amplifier, there are artifacts that show up. How do you judge these?
I can't imagine two different amplifiers not having even more artifacts than two of what should be the same.
That is how I got to the resistor vs the loudspeaker load test. The amplifiers I am familiar with do not drive resistors and loudspeakers the same. It is waaay to early for me to present the results of this bit of playing around.
Hi Ed,
I suspect that track is a bit "corked"...
I don't have the album, so I cannot comment.
I find that fine detail audibility depends on the speaker having a sensible directivity, e.g. no dome tweeters etc... The massive room scatter from dome tweeters tend to obscure a lot of stuff...
Ciao T
I suspect that track is a bit "corked"...
I don't have the album, so I cannot comment.
I find that fine detail audibility depends on the speaker having a sensible directivity, e.g. no dome tweeters etc... The massive room scatter from dome tweeters tend to obscure a lot of stuff...
Ciao T
Since the general agreement is that even the best amplifiers sound differently, let's talk about the best ones.
Of course, everyone will have a different opinion about which ones are "the best sounding amplifiers".
John, Charles and others, what is the best sounding amplifier you've ever heard in these categories (regardless of any measured performance like THD, IMD, etc.):
-tube amp with GNFB
-tube amp with no GNFB
-semiconductor amp with GNFB
-semiconductor amp with no GNFB
Of course, everyone will have a different opinion about which ones are "the best sounding amplifiers".
John, Charles and others, what is the best sounding amplifier you've ever heard in these categories (regardless of any measured performance like THD, IMD, etc.):
-tube amp with GNFB
-tube amp with no GNFB
-semiconductor amp with GNFB
-semiconductor amp with no GNFB
I don't think I mentioned a setup. I said that if you don't hear a difference between input and output signals, that amp was 'ideal enough' in terms of reproducing the music accurately enough. I have not done any comprehensible test to find out if my own or somebody else's amp meets this criterium.
Do you not agree that if we can hear no difference between input and output, that that is sufficient and necessary?
Or do I misunderstand you?
jan didden
Hi,
It depends on system context (mostly but not entirely speakers).
In a system that is compatible the "compatible" amplifier will be the best.
If we may choose everything freely than a high efficiency speaker of exceptional quality combined with a non-feedback single ended tube amplifier using specific pre WWII Tubes would be my personal choice.
Ciao T
It depends on system context (mostly but not entirely speakers).
In a system that is compatible the "compatible" amplifier will be the best.
If we may choose everything freely than a high efficiency speaker of exceptional quality combined with a non-feedback single ended tube amplifier using specific pre WWII Tubes would be my personal choice.
Ciao T
The best amps i ever heard are the Audionet Max and The Vacuum State KT88. They could not be different. The Max uses gobs of feedback and measures extremely well with nearly 1000W on tab into 2 Ohm. The Vacuum State is a zero NFB diffential design and the late and great Allen Wright told me that he had not even measured distortion during development. He was not interested in things like that. It was dead quiet though on my 100dB sensitive speakers and rather wideband and high power ( 4 x KT88 per mono block ). The Max sounds extremely accurate and pristine but without being harsh. There is a nothingness to sound that my classical oriented audiophile friends find irresistable. They tell me that they can follow the partitur to the nth degree. It throws a big stage if its on the record. I can hear no loss of micro detailing and that was also reported from the ones that use it in other systems. Allens amp is something different. It does not analyse the music. It simply playes the music in such a beautifull and mesmerising way that you simply forget in a minut that you are listening to your HiFi.
Pick your poison.
Pick your poison.
Hi Jan,
Not quite. Your originally wrote in the original post:
To me this writing signifies that according to your testing "the best ones out there have no audible difference between their input and output signals".
It it merely expresses a belief, not rooted in actual experiment, as it now appears, than I am forced to disagree at this time with your contention, for lack of actual and tested evidence.
It is noble a belief to hold, for sure, I tend to be much more circumspect in my beliefs.
Ciao T
Not quite. Your originally wrote in the original post:
To me this writing signifies that according to your testing "the best ones out there have no audible difference between their input and output signals".
It it merely expresses a belief, not rooted in actual experiment, as it now appears, than I am forced to disagree at this time with your contention, for lack of actual and tested evidence.
It is noble a belief to hold, for sure, I tend to be much more circumspect in my beliefs.
Ciao T
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