Cgs synth

I finished mine today!

http://pugix.com/synth/cgs-dual-cmos-filters/

I have a few questions about the CV range. First, I followed Ken's
wiring diagram, which runs the FREQ pot between ground and +15V. During
my initial check of the module, it sounded thin and didn't go into low
frequencies. After I patched a +/-5V LFO to the CV input, it would go
down low with a negative voltage input. So it seems to me that the FREQ
pot should be connected to -15V, not ground. This is more of an
observation than a question. The question is what input resistor to use
with it. The 100K value seems too small. I'm going to change this to 270K.

The second, related, question is: How should the trim pot be tuned? It
sets the CV range. I'll probably set it to a sensitivity I like, but I
was wondering if it should be calibrated to 1V/octave.

Thanks,

Richard Brewster

>I finished mine today!
>
>http://pugix.com/synth/cgs-dual-cmos-filters/
>
>I have a few questions about the CV range. First, I followed Ken's
>wiring diagram, which runs the FREQ pot between ground and +15V. During
>my initial check of the module, it sounded thin and didn't go into low
>frequencies. After I patched a +/-5V LFO to the CV input, it would go
>down low with a negative voltage input. So it seems to me that the FREQ
>pot should be connected to -15V, not ground. This is more of an
>observation than a question. The question is what input resistor to use
>with it. The 100K value seems too small. I'm going to change this to 270K.

Fair observation, and yes, 270k sounds like an appropriate resistor if you
are using + though - on your pot.

>The second, related, question is: How should the trim pot be tuned? It
>sets the CV range. I'll probably set it to a sensitivity I like, but I
>was wondering if it should be calibrated to 1V/octave.

Yes, 1 volt per octave.

Ken
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
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