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It's good to run pots and sensitive parts of the VCOs off some internal regulators rather than relying on the power rails. Opamps can be powered from any supply but not the voltages used for setting pitch and the comparator trip point in particular. You can usually isolate those points quite easily.

From: cgs_synth@yahoogroups.com <cgs_synth@yahoogroups.com> on behalf of Ken Stone otherunicorn@... [cgs_synth] <cgs_synth@yahoogroups.com>
Sent: Friday, 6 October 2017 8:45 PM
To: cgs_synth@yahoogroups.com
Subject: Re: [cgs_synth] Clean/Dirty power supplies

VCOs on their own PSU can be good. VCAs and VCFs may pick up clicks off noisy power rails, but are unlikely to be affected to the same extent as a VCO.

Shielded cable will not help.

Extra caps on the VCOs, and thicker power wires may help. Having their own wires that run back to the PSU might help.

Ken

On Fri, Oct 6, 2017 at 8:16 PM, Mike Burnham mikejburnham@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

I recently built a few more PSUs for my modular but I noticed the other day that the VCOs are ever so slightly unstable and seem to be modulated by other stuff on the power rail. I notice that Yusynth designed an oscillator with onboard regulators because of this problem.

I made sure there is plenty of headroom for each PSU

I presume VCOs are really sensitive to these forms of modulation.

I have heard mention clean and dirty power supplies. Should all VCOs VCAs and VCFs be hooked up to one PSU and all logic/lfos/modulators etc hooked up to a dirty supply?

Also is it a good idea to use shielded cable for power?

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

Cgs synth

Re: Clean/Dirty power supplies

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