Cgs synth

Hello everyone -- This is my first post on the group, but I've been
watching for a while.

I finally got around to wiring up my Cynare and everything seems to be
functioning correctly except the VCF. There seems to be some signal
bleedthru. With nothing connected to VCF In, and listening to VCF
Out, I can hear the oscillators faintly, and also a loud impact thump
when the module receives a trigger. I've checked all of my
connections thoroughly and everything looks okay, so I'm a bit confused.

It appears that the filter itself only has a minimal effect on this
bleedthru noise. If I listen to +15v, I hear the same signal that is
bleeding thru.

I've uploaded a sound sample here of the VCF Out with nothing
connected to VCF In, and a trigger sequence being played:
http://www.lzxindustries.com/bad_cynare.mp3


Do I have bad transistors in the circuit? Mix out, noise, VCA in/out
all seem to be functioning perfectly, as does the filter (except of
course the bleedthru signal.) If you have suggestions to point me in
the right direction(s) I would greatly appreciate it.

Thanks,
Lars Larsen
creatorlars@...

>I finally got around to wiring up my Cynare and everything seems to be
>functioning correctly except the VCF. There seems to be some signal
>bleedthru. With nothing connected to VCF In, and listening to VCF
>Out, I can hear the oscillators faintly, and also a loud impact thump
>when the module receives a trigger.

The thump is probably the impact sound.

>It appears that the filter itself only has a minimal effect on this
>bleedthru noise. If I listen to +15v, I hear the same signal that is
>bleeding thru.

Your power supply is inadequate for whatever reason. At the very least, the
power rails need more decoupling near the cynare. It may also be supplying
inadequate current.

Ken
_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Awesome, thanks Ken. I found the previous discussion about this issue and
rewired the module to use the toggle switch as recommended. I also changed
the R-GAIN resistor to 1.8k as the output was very low compared to my other
drum modules. This seems to have almost removed my issue, but I will
experiment with different power supplies too.



This module is awesome!! Triggered via my Midibox SEQ3 with variable
gatelengths, there is so much potential for expression. I've attached a
picture of the module with my custom silkscreen-it's a pretty crappy
silkscreen job, but I kind of like it that way for my personal stuff anyway.
You can see it next to my Thomas Henry Clangora. (These two modules
complement each other very nicely.)



I'll post some sound samples too. Are there sound samples of the Drum
Simulator & Chime Simulator anywhere?



Cheers,

Lars







From: cgs_synth@yahoogroups.com [mailto:cgs_synth@yahoogroups.com] On Behalf
Of sasami@...
Sent: Saturday, April 19, 2008 7:16 AM
To: cgs_synth@yahoogroups.com
Subject: Re: [cgs_synth] Problems with Cynare filter