Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

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Re: Well

Posted by bwaslo on February 27, 2007 at 17:26:56:
I suspect you haven't read the documentation that comes with the program. No offense, but there's a lot written there about that. Here's a summary:
Recording with mics in a normal listening room isn't likely to be usable, the thing is insanely sensitive to even teeny differences. Things like the mic or speaker moved several mils, very exact positions of reflective sources including the person doing the recording in the room, even in other rooms that open into the measurement room, maybe air currents and temperature changes). I've not obtained a good silent difference track with acoustical signals when testing with no changes at all between recordings (a good verification test for setups).
For similar reasons, I doubt it would work with turntable sources either (though I haven't tried) because of changes in the vinyl after the first playing. Maybe if it were done on different days after the plastic has relaxed again it might work, if the turntable speed was consistent enough.
But electrical signals can be recorded from speaker terminals or at line levels between any components in the chain. As long as what is being changed comes before the place where you record from, you should be able to pick up differences in the audio electrical signal.
So devices to test might include cables, CD treatments, contact enhancers, AC Power enhancers, vibration control devices, etc. (unless they are having their effect on the listener by some way other than through the electrical audio signal).
So things like speaker drivers (which are generally agreed to make a difference anyway), room resonators, other stuff that doesn't act on the electrical signal probably can't be tested with Diffmaker, at least not without special isolated conditions and extreme care. It doesn't do everything, but neither does any other test. Use where appropriate.
I'm really not out to prove that things don't make a difference (that couldn't be proven anyway unless every possible situation was evaluated). But the reverse is provable, and by only ONE universally repeatable example! I keep seeing finger-wagging audiophile posts here and elsewhere about how engineers aren't measuring the right thing. So here's an attempt to do that. I can't do scientific investigation and find those measurements without actual evidence (as opposed to testimonials), so the idea was to get evidence where it may be gettable, and also to maybe give me and others a feel for the degree of difference being made (or not made).
I'm not trying to take away anyone's toys, OK?
It will take only one repeatable example of an audible effect (that isn't explained by current theory) to allow actual research on it to start (and fame for the lucky engineer who gets first crack at it, too). Help me out here, if you want to (not just EStat, anyone else, too). If you really want someone to "measure the right things", that is.