Join Date: Jun 2003
Location: Kenfield, CA, USA
Allpass filter design using passive components
Does any1 have any experience of using allpass filters in audio?
An allpass filter does not effect the amplitude of any signal, but it does effect the phase. Hence it can be used to correct the phase shift caused by use of Butterworth-type filters. Does any1 know how to do this?
Also, has any1 compared (listened) to the difference between a lowish order Butterworth and a highish order Bessel? I recall that Thorsten and Elso Kwak have a different approach to this in their treatment of filtering in non os dacs, but what is the difference in sound between a perfect square wave response, higher order Bessel and a phase shift (distorted) low order Butterworth.
Maybe I should just build them both and tell you!!