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Coefs - Biquad?

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Coefs - Biquad?

Postby lalalandsynth » Tue Jun 18, 2019 6:21 pm

Can someone explain to me how I can use the Coefs and Biquad module and the relevant coefficients to make a filter ?
And do I need to stack them to make a proper filter ?
Also , why do they have stream inputs ?

As In when I hook it up its just a lowpass filter

Sorry for the basic nature of these questions but I want to learn :)
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Re: Coefs - Biquad?

Postby martinvicanek » Tue Jun 18, 2019 8:10 pm

There are various prims in FS:

Biquad is a lowpass filter, however it is buggy for low corner frequencies.

2P2Z is a generic biquad with 2 poles and 2 zeros. Watch out when taking coefficients from the literature: the a's and b's are the other way around!

Coefs is a lowpass coefficient calculator which may be placed before the 2P2Z prim. Unfortunately this module is also buggy at low frequencies.

The coefficient inputs are of the stream type to allow continuous modulation. However do not modulate too fast else your filter will run away and kill the audio stream. For fast modulation I recommend the ZDF topology.

If you stack two filters (in series) you get a steeper filter.

You can create your own filter using the RBJ audio cookbook.

You might want to check my Optmized Biquad Filters at FS Guru, too.
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Re: Coefs - Biquad?

Postby lalalandsynth » Tue Jun 18, 2019 8:34 pm

i wonder if the 2P2Z has been removed from the Alpha , cannot find it ?

And yes,I noticed the A0 , which should be B0 right ?
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Re: Coefs - Biquad?

Postby wlangfor@uoguelph.ca » Wed Jun 19, 2019 12:44 am

Has FS Furu overcome the https certificate issue?

martinvicanek wrote:There are various prims in FS:

Biquad is a lowpass filter, however it is buggy for low corner frequencies.

2P2Z is a generic biquad with 2 poles and 2 zeros. Watch out when taking coefficients from the literature: the a's and b's are the other way around!

Coefs is a lowpass coefficient calculator which may be placed before the 2P2Z prim. Unfortunately this module is also buggy at low frequencies.

The coefficient inputs are of the stream type to allow continuous modulation. However do not modulate too fast else your filter will run away and kill the audio stream. For fast modulation I recommend the ZDF topology.

If you stack two filters (in series) you get a steeper filter.

You can create your own filter using the RBJ audio cookbook.

You might want to check my Optmized Biquad Filters at FS Guru, too.
Download VST: LA Bands 15 Band EQ
My Website http://www.leattol.com
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