It can be used with just about any source- the critical thing is the load, since the caps are 1uF. An amp with 100k or more of input impedance will do just fine. In my own tests of myself, I used both digital (ripped files and M-Audio 192 soundcard) and analog (phono). But the idea of the box is that I can take it with me and plug it into anyone's system.
You are correct, except at the time, virtually all audio testing used SYMMETRICAL TEST SIGNALS. Music is not symmetrical. Now, even then an asymmetrical pulse would have found it, but they didn't have convenient analysis for that, back then.
The biggest difference is that Richard Heyser was trying to show people how something could sound different with music yet still measure OK.
What SY insists on is that everything really sounds the same, and it is only in our expectations that anything subtle sounds different. I don't go for it.
The biggest difference is that Richard Heyser was trying to show people how something could sound different with music yet still measure OK.
What SY insists on is that everything really sounds the same, and it is only in our expectations that anything subtle sounds different. I don't go for it.
I call shenanigans. When have I ever said anything like that?
Show me something electronic that has been demonstrated to sound bad but measure well under the listening test conditions.
edit: I deliberately omit transducers, where interpretations of measurements are far more complicated. And I used the qualifier "under the listening test conditions" to exclude clipping and oscillation; I've been pretty vocal about the audibility of amps with differing overload recovery and design my own amps specifically to be excellent in that regard.
I'd like to point something out - most of us (not all) on here are getting "older" which means our hearing is declining. Also, some people NEVER really have "good hearing".
When I was young, I could hear into the ultrasonic (yes, it was quite annoying). It was rather easy to hear some distortions that quite frankly are totally inaudible now. I know that because I don't hear any of them now!
Sometimes I wish I could still hear that very HF stuff, sometimes not. It made it easy to discern many of the things that we discuss now. (not all of it, just much)
You all should think about this...
_-_-
PS. SY, happy to take ur cap test - not hard to pass that here I suspect. (there is an AC and DC coupled input on my Symphony No. 1 amp, not terribly hard to hear the diff - subtle though) When are you coming over?
When I was young, I could hear into the ultrasonic (yes, it was quite annoying). It was rather easy to hear some distortions that quite frankly are totally inaudible now. I know that because I don't hear any of them now!
Sometimes I wish I could still hear that very HF stuff, sometimes not. It made it easy to discern many of the things that we discuss now. (not all of it, just much)
You all should think about this...
_-_-
PS. SY, happy to take ur cap test - not hard to pass that here I suspect. (there is an AC and DC coupled input on my Symphony No. 1 amp, not terribly hard to hear the diff - subtle though) When are you coming over?
This is just the opposite of what I test for. I test for audio differences, even when the measurements are similar. SY tests for audio sameness, even though we could measure a difference.
While this test may have some merit, I would hold that it does not have enough deviation to make it worthwhile. I don't expect just one cap to be obvious, unless it has real problems, but a series of caps and other attendant compromises does seem to make a difference. When I remove the coupling caps in a preamplifier, I might be removing 6 caps per channel, for example, or even more, not just one.
While this test may have some merit, I would hold that it does not have enough deviation to make it worthwhile. I don't expect just one cap to be obvious, unless it has real problems, but a series of caps and other attendant compromises does seem to make a difference. When I remove the coupling caps in a preamplifier, I might be removing 6 caps per channel, for example, or even more, not just one.
You don't want to rely on trust in a scientific endeavour.
You don't want to end up with a positive result and then someone on the other side accuses you of measuring it secretly and thus scoring well. People are people
jd
it depends.
do you want answers
or just to be published?
No it does not depend. If you are serious about the results being trustworthy, beyond a shadow of a doubt as far as you can manage, you take care of these issues.
jd
that's why we get nowhere in the discussion.
i can't prove it
therefore i can't hear it
According to a piece in a 1989 issue of the BAS Speaker, "...Richard Heyser devised a hypothetical device that has good frequency response, no noise and no distortion but speech passed through the box is unintelligible. In the black box is a computer that recognizes test tones and if the test tones are not present, the output is intermittently shorted to ground."
I've not been able to find any evidence that any such "black box" was was ever actually constructed.
se
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