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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Re: changed the subject line...again! and again posted by Dan Banquer on April 26, 2004 at 09:48:13:
DB: ""Any reasonably well designed amp or pre amp will have uniform group delay also. ""Any you can prove that? :-)
It's not that difficult to make high bw amps..and measure them using normal techniques.
But how do you test them for R-L delay artifacts???
Example:
Amp...load, speaker....cable..
Signal 40 hz, Pout = 300 wrms, one channel only.
Output V/I: heavily into all four quadrants.
Now, add a hf signal to both channels..
Time correlate the hf on both channels.
Do the leading and trailing edges line up temporally? This involves verifying that the hf signal is temporally accurate to the tune of 1.5 uSec..What do you imagine a 200 nHenry per foot wire would do to a 12 Khz squarewave signal leading and trailing edge? Perhaps 10 uSec delay?. Is the amp controlling the load on the other end of that 2 uhenry inductor? (10 feet) Is the amp capable of keeping the zero crossings that well (1.5 uSec), with such a current slew limiting thing in the way? Geeze, I'll even take 5 uSec, or 10...
Bottom line: Given the ramifications the Nordmark paper could have on human perception issues, (assuming it is correct), I don't know what is going on..but the research he did is rather interesting.
And I believe that there is nobody around who has ever tried to measure the temporal domain at high power with any real accuracy. I may be wrong..but so far, nobody has chirped up to say otherwise.
Cheers, John
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Follow Ups
- Re: changed the subject line...again! and again - jneutron 10:19:17 04/26/04 (5)
- Re: changed the subject line...again! and again - Dan Banquer 11:08:12 04/26/04 (4)
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