Author Topic: Modulating cutoff for the bandpass filter  (Read 1022 times)

widdly

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Modulating cutoff for the bandpass filter
« on: August 26, 2014, 07:19:30 AM »
I cannnot get the bandpass filter cutoff to modulate.  If I create a patch with a LP filter and set a modulation matrix to use P1 to modulate the cutoff it works properly.  When I change the filter type to BP, I cannot seem to move the cutoff using P1.  Anyone else having this problem?  Perhaps I'm missing something.

Xavier

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Re: Modulating cutoff for the bandpass filter
« Reply #1 on: August 26, 2014, 01:45:33 PM »

It's a know limitation.
Because changing the BP middle frequency requires several heavy operation, so i didn't want to make it change all the time with a modulator.
I think i'll change that.


widdly

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Re: Modulating cutoff for the bandpass filter
« Reply #2 on: August 26, 2014, 04:16:01 PM »
I just had a look at the code.  The LP and HP code is pretty tight.  I wonder if you could change the BP to a LP and HP in series.  Remove the resonance parameter and add a width parameter.  The width would be an offset between the LP cutoff and the HP cutoff.  The Yamaha SY-77 had something like that.

toneburst

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Re: Modulating cutoff for the bandpass filter
« Reply #3 on: August 28, 2014, 05:05:54 PM »
The Machinedrum and Monomachine (and possibly other Elektron gear) have a similar setup and cascaded low and high-pass filters.

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toneburst

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Re: Modulating cutoff for the bandpass filter
« Reply #4 on: August 28, 2014, 05:07:29 PM »
@widdly it would be a shame not to have resonance on the BP filter, though.

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