I did some experiments with using brickwall (elliptic) IIR filters and combining them with some allpass filters to move some parts of the overshoot to the other side of the edge (like in a sawtooth or square wave), i.e. distribute the overshoot more symmetrically between the left and right side of the discontinuity. Initially, due to the minimum phase characteristic of the elliptic filter, all the overshoot is on the right side. With the allpasses, I can reduce the overshoot on the right side at the expense of introducing some overshoot on the left side (where previously was none). I'm considering to use that technique in the future for brickwall IIR filters. Edit: after doing these experiments, it occurred to me that I'm actually manually trying to design a phase-correction allpass. Something like this:I did run some experiments. Shifting the phase of partials can indeed help to reduce the ringing around discontinuities in the waveform. However then it always appears somewhere else. So in short: it won't help in practise
https://spinlab.wpi.edu/courses/ece503_ ... xample.pdf
Of course, for (symmetric) FIR filters, the ripple is already symmetrically distributed to both sides of the edge in the first place, so in such a case, an allpass won't help.
Statistics: Posted by Music Engineer — Mon Mar 25, 2024 8:35 pm