# Questions tagged [allpass]

Use this tag for questions related to filters that change the phase relationship of a signal, but does not change the gain (amplitude) of the signals.

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### Does flat group delay bandwidth of a Thiran filter increase with increase in filter order?

Experimentally, it does seem that for a Thiran allpass delay filter of desired low-frequency group delay $D$ with filter order $N$, increase in filter order $N$ increases bandwidth of the frequency ...
2 votes
1 answer
80 views

### Stability of N-order Thiran delay filter when required passband delay is N+1

In this lecture note, on page 7 (or page 111, the same page), it is said that the Thiran allpass delay filter of order N with passsband delay N+1 reproduces samples with zero error. I find it hard to ...
5 votes
1 answer
177 views

### Understanding conversion of frequency-warped signal and its orignal signal

I'm reading an article Frequency-Warped Signal Processing for Audio Applications which is talking about frequency warping. An open access version of this artical is available here. Say a signal or ...
• 169
10 votes
4 answers
285 views

### Minimum Phase - All Pass Decomposition For Large Linear Phase Filters

UPDATE: I am looking for a robust approach to decompose linear phase FIR filters with 100s of coefficients into its minimum phase and all pass components. I originally thought determining all the ...
• 36.1k
0 votes
1 answer
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0 votes
1 answer
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### Finding minimum-phase/allpass of transfer function

I am trying to find the minimum-phase system of the transfer function $H(z) = \frac{2 + 3.125z^{-2}}{1-0.9z^{-1}+0.81z^{-2}}$. I know I need to find and remove the allpass (basically reflect the two ...
• 33
0 votes
2 answers
872 views

### 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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0 votes
1 answer
2k views

2 votes
2 answers
3k views

### 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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2 votes
1 answer
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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 ...
• 123
4 votes
3 answers
1k views

### 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 ...
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