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CGS 64 VCA

CGS 64 VCA

2015-12-06 by hiko_goldenballs

Hello Ken and all.


I've constructed the cgs 64 VCA.

The thing is that an audio signal in the input can not be gain zero. I adjusted the CV INIT trimmer but the signal doesn't disappear. I could more or less perfectly eliminate the CV signal in the CV input by adjusting the trimmers, following the set up instruction.

One thing I haven't done is that I used unmatched 548s, but don't really know how much it affects to.

I've used a 2SC 2559 for the Dual transistor.


It would be very helpful if anyone could give me a clue.


Thank you very much.


Fuyuhiko


Re: CGS 64 VCA

2015-12-06 by Ken Stone

The CV init trimmer should be able to trim it to a minimum level. Getting "perfect" silence is unlikely with any VCA. Failing to match the BC548s would probably cause your problem.

Cheers,
Ken
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On Sun, Dec 6, 2015 at 1:55 PM, hiko_goldenballs@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Hello Ken and all.


I've constructed the cgs 64 VCA.

The thing is that an audio signal in the input can not be gain zero. I adjusted the CV INIT trimmer but the signal doesn't disappear. I could more or less perfectly eliminate the CV signal in the CV input by adjusting the trimmers, following the set up instruction.

One thing I haven't done is that I used unmatched 548s, but don't really know how much it affects to.

I've used a 2SC 2559 for the Dual transistor.


It would be very helpful if anyone could give me a clue.


Thank you very much.


Fuyuhiko





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

Re: CGS 64 VCA

2015-12-06 by hiko_goldenballs

OK, it seems like the 548s are the cause of the problem, I will try to get it.

Thanks for your quick reply.

Cheers

Hiko

Re: CGS 64 VCA

2015-12-07 by Chris Juried

Hi,

What method are you using to match your 548's? Curve Tracer? Meter with emitter referenced to shorted base/collector? Thanks.
Sincerely,
Chris Juried
Audio Engineering Society (AES) Member
InfoComm-Recognized AV Technologist
http://www.juriedengineering.com (Juried Engineering, LLC.)


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From: "hiko_goldenballs@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Sunday, December 6, 2015 5:21 AM
Subject: [cgs_synth] Re: CGS 64 VCA

OK, it seems like the 548s are the cause of the problem, I will try to get it.

Thanks for your quick reply.

Cheers

Hiko


Re: CGS 64 VCA

2015-12-07 by hiko_goldenballs

I don't really know how to much it. All I know is put the transistors into a meter.

Thanks

Re: CGS 64 VCA

2015-12-08 by hiko_goldenballs

Thank you very much for the link!

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