"[ ] There are, to be sure, subjective distortions that are level
dependent and as such are thought to be nonlinear distortion, but they are in fact linear effects that
have a nonlinear perception. The testing of this hypothesis is currently underway and the results
will probably be available in the future."
I'm looking forward to the testing results of something that's pretty much nonsense to begin with.
The author of this doesn't really understand it.
Jan
dependent and as such are thought to be nonlinear distortion, but they are in fact linear effects that
have a nonlinear perception. The testing of this hypothesis is currently underway and the results
will probably be available in the future."
I'm looking forward to the testing results of something that's pretty much nonsense to begin with.
The author of this doesn't really understand it.
Jan
That may be. However the work on HD perception, IIUC, has since been reproduced by others?
I don't think anyone should expect psychoacoustics to be as predictable and straightforward as say, comparing IM distortion specs of amplifiers. Two people can perceive two different things from the same stimulus, and neither person is wrong. In contrast, measuring two amplifiers will clearly differentiate which one is "less wrong" than the other.
Only in one dimension though. Making it less wrong in that dimension might risk making it more wrong in another dimension. For example, what if increasing loop gain to reduce distortion happened to increase susceptibility to EMI/RFI? Or with more loop gain, what if excess noise in feedback resistors added more correlated noise to the amplifier output? Not saying such examples are likely or common. Just saying trying to fix one thing can sometimes have unexpected side effects on other things.
I know about the juggling and I've done it.
It's still more objective than asking two people which amplifier has more distortion. Unless one amplifier is grossly inadequate, the answers will be for all practical purposes subjective.
You can make up your own tests and make up predictions if you don't like the conventional tests. Example I have an old boombox that boasts 110 WATTS! 55x2 watts RMS. I predicted they wouldn't be the same 55 watts a channel as my Nakamichi 55x2 amplifier. When I tested I found that the boom box did indeed provide 55 watts into 4 ohms one channel for about a fifth of a second, but with both channels driven into 4 ohms I was able to get about 12 watts steady state per channel. But the Nakamichi could drive 55 watts x 2 into 8 ohms indefinitely.
Now I further predict that this difference would be audible in a blind test. Certain passages would be audibly cleaner when driven by the Nakamichi. I didn't do the test but if anyone cares they can do it for themselves.
It's still more objective than asking two people which amplifier has more distortion. Unless one amplifier is grossly inadequate, the answers will be for all practical purposes subjective.
You can make up your own tests and make up predictions if you don't like the conventional tests. Example I have an old boombox that boasts 110 WATTS! 55x2 watts RMS. I predicted they wouldn't be the same 55 watts a channel as my Nakamichi 55x2 amplifier. When I tested I found that the boom box did indeed provide 55 watts into 4 ohms one channel for about a fifth of a second, but with both channels driven into 4 ohms I was able to get about 12 watts steady state per channel. But the Nakamichi could drive 55 watts x 2 into 8 ohms indefinitely.
Now I further predict that this difference would be audible in a blind test. Certain passages would be audibly cleaner when driven by the Nakamichi. I didn't do the test but if anyone cares they can do it for themselves.
Which two people? Someone who has been doing it successfully for a living for many years? Someone off the street? What kind of speakers would you use to most clearly hear the amplifier? horns, box speakers, electrostatic? What about the room, is it suitable for serious listening tests? IOW, its not just about asking two people, its about designing the experiment to produce high quality listener feedback on the sound. Same as with your other test gear, do you make sure it is well-suited for what you want to measure? Do you read the manuals so you know how to use it? Or do you just pull in two people and say, here, measure this. Then let them fumble around with it?
The same amplifier will have different distortions in different rooms, furthermore the influence of the local vicinity affects the sound, too. Distortion is distortion, you can’t separate distortion into component parts. You don’t realize it’s there until you figure out how to get rid of it. As Bob Dylan says at the end of all his records, good luck to everybody.
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I don't disagree. But at some point even a trained ear won't tell the difference. Distortion levels are so low today that any improvements are academic. I would predict that repeatable perceived differences in amplifiers are the result of something other than the usual THD and IMD. And there are other types of distortion (as referenced by Cordell, Self, and likely others) than THD and IMD. That's why I used two amplifiers that would almost certainly be parsed in a blind test. The obvious difference is in the dynamic range, and I'm certain I could craft a test procedure that would highlight this. And don't be fooled; the cheapo amplifier is surprisingly competent driving large and inefficient speakers. But test tones make it droop severely where the Nakamichi doesn't.
Distortions in rooms is more about loudspeakers I think. Many issues commonly blamed on speakers is actually the room acoustics.
Same issue i mentioned early in the thread. The hifi/radio stimulates the creation of the music in their heads. They make music for a living and they make it up listening to gear.
dave
I know several professional musicians and a couple are hifi nuts but most aren't. The ones that aren't just say the structure of the tune or the melody is enough for them to enjoy, they don't care about pretending they are at a concert. Nobody mentioned what I think you've stated.
That has been the case in my mind since the late 1970’s after the Japanese rush towards low numbers with little care for the sonics.
Distortion is a form of information loss, its precence buries/masks little bits of information. But thinking of adding things suggests that the device is perfect with added imperfections. This approach leaves lots on the ground to pick up, it blinds the observer from what is being lost because they are only looking for what is added.
dave
First, to make it clear, defining distortion as what is different (added or lost) from the original signal, the amplifier VERY much makes a difference. And an amplifier’s quality cannot really be evaluated without being considered as part of a system with the loudspeaker and what connects them.
For instance, my SIT-3 is a VERY good amplifier for most of the loudspeakers i have, but i dount it would driver DW XG-8s very well. @Nelson Pass?
dave
If the typical consumer knew how much HD that even a good loudspeaker introduces, they'd be mighty confused.
The nature of the HD from a solid state amplifier can make the amplifier sound "gritty, veiled, sweet, detailed," ad nauseum. These are subjective terms. The biggest contributor of distortion in a competently designed amplifier will be the crossover distortion, which produces higher harmonics. Modern designs have done a good job of minimizing this; even op amps can produce crossover distortion but is it an issue?
The nature of the HD from a solid state amplifier can make the amplifier sound "gritty, veiled, sweet, detailed," ad nauseum. These are subjective terms. The biggest contributor of distortion in a competently designed amplifier will be the crossover distortion, which produces higher harmonics. Modern designs have done a good job of minimizing this; even op amps can produce crossover distortion but is it an issue?
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