Monday, December 1, 2008

tube vca pcb design

i just did a redesign for the 5672 pentode vca circuit that was originally posted by j.barrs on that dutch synth forum and i added some summing lines and a final gain stage. there is also a pwm type effect that brings some unique tonal qualities to the signal as the vca opens and closes. there are lots of trim pots in the design which can all be brough to the panel if the builder feels necessary. they include: input attenuation (which attenuates the final sum of all the inputs), pw (changes the power feeding the tube which brings the nice pwm effect), final boost. there is also a switch to starve the heater and bring about some different tones.

the starve mod and pwm mod were made my crashlander and freqeuncy central. eric metasonix also helped me work out how to get a nice linear responce (-0.4v dc offset). so all i did was really add the summing stage, final gain and design the layout. here it is

the pdf version can be downloaded in this thread


Fer said...

I know this is old but imho with a timeless value. So, thank you so much.
Do you have the schematic for this layout?
I only have the J. Baars schematic
Thanks again

Fer said...

(in fact I have two schematics "low impedance output" and "high impedance output")