frequency control of higher order filter with mono pot

okmog · 29th August 2011, 11:15 AM

Hi,

I would need a (low phase shift) 12 dB high-pass filter, where I can change the cut-off frequency just with a mono pot.
Is this possible, since a 12 dB filter is a 2-pole (when using caps and resistors) and the cut-off frequency of each pole has to be changed simultaneously and so I would need a stereo pot.

Any experiences?

mickeymoose · 29th August 2011, 01:59 PM

THAT app not 130 describes a VCA controlled state-variable filter. Not quite what you want but maybe a guide. E

jcx · 29th August 2011, 02:16 PM

its got one knob...

okmog · 03:44 PM

Thanks for your posts.

The mechanical solution would be probably too "expansive"

VCA solution should work. Is this standard solution filter freq by a pot? I can't remember haven't seen VCAs in synthesizer filters ...

phase_accurate · 2nd September 2011, 01:38 PM

If you impolement your filter as state-variable filter you might control it using CMOS analog switches and a pulse-width modulator.

Regards

Charles

29th August 2011, 11:15 AM	#1
okmog diyAudio Member Join Date: Feb 2010	frequency control of higher order filter with mono pot Hi, I would need a (low phase shift) 12 dB high-pass filter, where I can change the cut-off frequency just with a mono pot. Is this possible, since a 12 dB filter is a 2-pole (when using caps and resistors) and the cut-off frequency of each pole has to be changed simultaneously and so I would need a stereo pot. Any experiences?

29th August 2011, 03:28 PM	#4
okmog diyAudio Member Join Date: Feb 2010	Thanks for your posts. The mechanical solution would be probably too "expansive" VCA solution should work. Is this standard solution filter freq by a pot? I can't remember haven't seen VCAs in synthesizer filters ... Last edited by okmog; 29th August 2011 at 03:44 PM.

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29th August 2011, 01:59 PM	#2
mickeymoose diyAudio Member Join Date: Nov 2008	THAT app not 130 describes a VCA controlled state-variable filter. Not quite what you want but maybe a guide. E

2nd September 2011, 01:38 PM	#5
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	If you impolement your filter as state-variable filter you might control it using CMOS analog switches and a pulse-width modulator. Regards Charles

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