In Reply to: Re: A correction on one point posted by tomservo on December 11, 2006 at 16:08:41:
>One gets a phase plot one expects from those amplitude changes.'Expects' on the basis of Hilbert phase? Or--?
>Now, using a dsp speaker controller, construct this filter alignment
The DSP will give the same phase as a modeled analog minimum phase filter? It doesn't have to, it can be even linear phase. One can make about any phase and amplitude response one wants to (with a significant delay added, of course).
Take a look at the theory used in MLS (such as Rife and Vanderkooy, "Transfer-Function Measurement with Maximum-Length Sequences" JAES Vol. 37, No. 6). It is a deconvolution of output vs. the input, and the first result is the impulse response, about as straightforward as it gets -- and the result is the same as you get if you directly measure the impulse response with an impulse input. The test needs to use an MLS length long enough to represent the IR of what is being measured and also the microphone response (including its phase response) is going to be a big player. The phase response will be significantly affected even a decade from the mic's response cutoff -- a better reality check would be to measure an electronic all-pass network, then mic issues aren't involved.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: A correction on one point - bwaslo 05:40:01 12/12/06 (2)
- Re: A correction on one point - tomservo 07:12:46 12/12/06 (1)
- Re: A correction on one point - bwaslo 09:32:05 12/12/06 (0)