# Tagged Questions

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### filtering in frequency domain

I am performing decorrelation of two channels of audio using all pass filtering. The two all pass filters for two channels are of very high order (>1000 but with not all coefficients non zero). I have ...
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### All pass systems- Poles and Zeros

If an All Pass system has poles at $0.8\exp\left(-j \dfrac{\pi}{4}\right)$ and $0.8\exp\left(j \dfrac{\pi}{4}\right)$, There would be $2\pi$ jumps in the phase (principal value) at angular frequency ...
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### Allpass filter feedforward/feedback design and code

I want to design/implement a simple feedforward/feedback all-pass filter, and I am having some troubles and questions with it. From Shroeder design (based on J. Smith article here): I came up ...
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### 3 Band Crossover with Linkwitz Riley Filter

I would like to write a 3 Band "EQ" with BiQuad Filters but for some reason, I get some phase distortion. The problem already got discussed here. I found out that I need to work with Allpass filters ...
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### Unstable Cascade of Allpass Filters

I'm working with cascaded second-order allpass filters. Each filter is characterized by conjugate pole/zero pairs. In a long (>50) cascade of identical filters, the pole locations of the overall ...
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### Confusion about result of FIR All-pass filter design

I try to design a FIR All-pass filter with random phase in the frequency domain. I am a bit confused by my result and am not sure if the reason is a programming error or a misconception about ...
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### Allpass group delay formula and effect on Karplus-Strong

Some introductory questions: What is the unit of the group delay in a digital filter (is it samples?) What is $\Omega$ in the equations below (is it $\Omega=2 \pi\frac{f}{f_{sample}} ?)$ If I got ...
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### Resonant peak frequencies for phaser effect

I have a conventional phaser setup with allpass filters and feedback. I can calculate the peaks frequencies of the phaser when the allpass delays are set to 1 (then they work as simple one sample ...
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### How to delay a signal by D degrees

I read in a paper that a sound signal can be delayed by D degrees. How can such a thing be possible? Isn't sound signals expressed only in terms of the time axis? Thanks in advance
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### Minimum phase systems with pole at infinity

If a system is given by a transfer function in the z domain that has all poles and zeros inside the unit circle except for a factor of $z^{-1}$ in the denominator (pole at infinity), can it still be ...
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### How to design an all pass type filter with inverted phase response?

I want to model a "negative dispersion" in waveguides. Is it possible to design an all pass filter with inverted phase response? (e.g. -pi at 0 and pi at Nyquist)? I feel :) this could be possible ...
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### All-pass filter implementation in numpy

I'm playing with Python & numpy to filter audio. It is relatively straightforward to design and us low-high-bandpass/stop FIR and IIR filters, stuff can be done in a couple of lines. I'm ...
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### All-pass filters to remedy group delay

I would like to sum a filterbank made of bandpass butterworth filters to reconstruct an audio signal. Given group delays for each channel shown in the following plot . . . How would I go about ...