self made band-pass-filter, how ?

FaschingsPrinz

Hello friends,
I´m new to this forum and to the G2 and am seeking for help today.

I´m trying to build my own band-pass-filter from an low-pass and a high-pass. The bpf in the G2 does have a slope of 12 and 24db, but I would like to use other slopes too (the lfp & hpf-modules have pulldowns for 6 to 36db). Event though the slope will have to be adjusted in the editor, because they are in pull-downs.

What I would like to achive is a bpf, where I adjust the hpf (so the bottom-border of the band) and a displacement, where I can adjust a gap, defining the width of the band I want to get past the filter.

Something like:I adjust 1kHz on the bpf and adjust the width to 2kHz so I hear the band from 1-3kHz. When I adjust to 9kHz, I hear 9-11kHz.
I would like to use this bpf to cut bands out of white noise.

Any hints how I can coupple the lpf-frequency to the hpf-frequency ?

Thanx very much,

PS.: In a later attempt I would like to modulate this bpf with an oscilator (or LFO) so the band cut from white noise will oscilate.

drapdap · Posted: Mon Oct 11, 2010 2:33 am Post subject:

hallo Prinz!

most of everything you want to know about the g2 filters is
written down by Rob Hordijk, here:

http://www.xs4all.nl/~rhordijk/G2Pages/Filters.htm

part of: http://www.xs4all.nl/~rhordijk/G2Pages/

do read them, they are excellent!

as for coupling cutoff and such, you can use a constant module,
and patch it's outputs to as much parameters as you want.
you can assign a midi CC to that constant, and you work from there,
move as many cutoff's as you can fit in the dsp. Smile

also check out the morph group assignments, where you can even
determine how much you want to adjust these parameters, also with one know; or whatever that sends midi CC's, you have eight of these...

róbert

FaschingsPrinz · Posted: Mon Oct 11, 2010 4:33 am Post subject:

Hello,

thanx for the link to the manual.
I´ll try to dive into it tonight.

Regarding the use of a morph-group:
I thought about this already, but it seems like the morph-values do not work the way I would prefer it.
I adjust the hpf-frequency to a certain amount and assign the hpf-frequency-knob afterwards to a morph-knob and pull the "cake-slice" from it´s adjusted hpf-frequency value to full. I adjust the lpf-frequency to an amount higher then the one on the hpf, and assign it to the same morph-knob and pull its slice to full open too. (I have to adjust both frequencies here, but would prefer to adjust the hpf-cutoff and the width of the band)
I then do assign the two frequency-knobs additionally directly to two knobs on the G2 so they are displayed on the G2 (while moving) and this way can be checked visually.
But when I do now move the morph knob, the distance between the two frequencies does not stay stable.
I would like the width of the band to stay constant when I move the hpf-cutoff.

Thanx,
FP

ian-s · Posted: Mon Oct 11, 2010 1:47 pm Post subject:

You can use a mix2-1b to subtract a 'width' from a common frequency control. In Clavia Units, 12 = 1 Octave so setting width to 24 gives you two octaves of pass band between the high/low slopes.

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FaschingsPrinz · Posted: Tue Oct 12, 2010 1:23 pm Post subject:

Hello friends,

I´m not sure if it is already "worth" it beeing posted here, because for most of you it will pretty basic stuff, so please excuse me for that.
But with many Thanx to 'ian-s' I have been able to achive what I was looking for.

Thanx,
FP

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that´s how the result looks with photosounder :

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bpf.jpg

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that´s how it looks under ReAper with RecordMonitoring activated and a freeware VST osciloscope as a track FX :
freeware vst-osciloscope: http://sonictransfer.com/free-vstau-oscilloscope.shtml

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FaschingsPrinz

Yesterdays version was done for the G2-demo only.
Due to the fact that low frequencies where louder then higher frequencies, I did add a volume-compensation.
Now operable from the G2

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LFOnoiseG2.pch2

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LFO-modulated bandpassfilter on white noise, with volume compensation for low frequencies

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