All-Pass Circuits

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mediatechnology
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All-Pass Circuits

Post by mediatechnology » Tue May 05, 2020 1:12 pm

All-Pass Filters

The Elliptic Equalizer uses an All-Pass Lead Filter in the Mid channel to compensate the phase error of the Side HP Filter. Jung provides an excellent discussion of All-Pass filters that some of you may find useful.

All-Pass Filters from the 3rd edition of the "Audio IC Op-Amp Cookbook" https://proaudiodesignforum.com/images/ ... g_1987.pdf

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AnalogJoe
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Re: All-Pass Circuits

Post by AnalogJoe » Thu May 28, 2020 10:22 pm

There is a great treatment by Kugelstadt in TI's "Opamps for Everyone" chapter on All-Pass filters, including higher order All-pass. I had to design and build high order all-pass filters to implement analog delays for my PhD project, I wrote an optimization routine in MATLAB to find the optimum time constants of each filter to achieve a specific time delay, the book was of great help.

Check page 325 of this free book https://web.mit.edu/6.101/www/reference ... eryone.pdf

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JR.
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Re: All-Pass Circuits

Post by JR. » Fri May 29, 2020 9:10 am

Back last century, all pass filters were used inside premium analog loudspeaker crossovers to generate time alignment delay.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

AnalogJoe
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Re: All-Pass Circuits

Post by AnalogJoe » Fri May 29, 2020 10:43 am

JR. wrote:
Fri May 29, 2020 9:10 am
Back last century, all pass filters were used inside premium analog loudspeaker crossovers to generate time alignment delay.

JR
They are still used today!, Douglas Self talks about their application in his Active Crossover Design book. Although most are replaced by DSP these days.

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JR.
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Re: All-Pass Circuits

Post by JR. » Sun May 31, 2020 7:31 am

I was still selling cheap analog crossovers at last century, but Peavey was already making digital crossovers back then. Now the cost of putting DSP crossovers and more (like sophisticated protection circuitry) inside powered speakers has gotten even cheaper.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

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