>If you need extra VCA's *and* want to enrich your harmonic output,Don't isolate your grounds - it can cause potential build up between
>this may be the ticket. Of course, it may also force you to enrich
>your power supply requirements. Right now, I'm using a separate
>triple-output supply (+&-15 and +5vdc)for just the planned triple
>tube VCA. This would probably be better done with a separate 5 volt
>filament supply and a much larger dual-output supply for the synth's
>15 volt requirements. The present method will require me to isolate
>my tube VCA grounds from the rest of the synth modules to avoid
>ground potential hum. Hmmmmmmm....
modules. What I do is make sure the metalwork of the PSU is grounded to the
mains ground, but ensure that the 0V line is isolated from ground. I then
put a 1k 2W to 5W resistor between the 0V line and the case ground. This
keeps the 0V line from jacking itself up, and prevents hum loops. Of course
you will need to make sure the PSU is not bolted to a common metal chassis
with the other supplies.
Ken
_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>