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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: This is the premise and result published many times by ... posted by gymwear5@hotmail.com on December 15, 2009 at 13:14:25:
Okay, what is that thing... that two-microphone intensity system? I'd like to read up on it.
I'm always fascinated by speakers that sound better (or worse) than normal measurements say they should, as that's an indication that we have some ground still to cover regarding which measurements correlate best with subjective preference. The Shahinians are a superb example - apalling conventional measurements, but glorious sound.
I haven't read Toole's book, but I've read a lot of his papers. Actually I came to that conclusion via another route, back in the late 80's, but didn't know how to put it into practice until a few years ago. I wrote an article on the subject for SpeakerBuilder magazine in 1989 but it was rejected, and in retrospect I'm glad it was.
To get a handle on the power response, I now use a suite of time-gated off-axis measurements (something I couldn't have done twenty years ago). Takes a while, though. I virtually ignore the on-axis curve when doing crossover design, but still run it just so I can see how closely it tracks the off-axis curves.
In my opinion the two dominant factors in how a loudspeaker sounds are frequency response and radiation pattern, and I think they can be conceptually combined into frequency response across the 3-dimensional space the speaker radiates into. This can be approximated by a colorized polar map, which simultaneously displays frequency, angle, and intensity in one plane (usually the horizontal). Polar maps are occasionally seen in high-end prosound. The only home audio manufacturer who has published polar maps, to the best of my knowledge, is Earl Geddes.
In my experience when there's a big discrepancy between the conventional on-axis frequency response measurement and the subjective "sound" of a speaker, the explanation is most likely to lie in what's happening off-axis... as in the case of the Shahinians.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
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Follow Ups
- RE: This is the premise and result published many times by ... - Duke 14:29:47 12/15/09 (0)
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