Archive of the former Yahoo!Groups mailing list: tube synth diy

Hi all
looks like my first post describing this synth has disappeared
so try again.

finished first rack of a tube modular.
pics in Photos.
I am planning to build a few of each module so designed and etched
circuit boards for the circuits.

Eric Barbour VCO - works fine

Beat Frq VCO - I built an EB VCO and changed the cap around the
thyratron to get the operating range around 20-30kHz. The output goes
into a 6AR8 modulated by two neon oscillators set to run at 25kHz. It
"kinda" works but needs some sorting. Neon oscillators are apparently
quite unstable above 10kHz, which I view as a good thing, at the
moment it seems they only fire at certain settings, maybe too
unstable.....anyway, debugging to do.

Rene's VCF - built two of these, both with sync-able neon LFOs, the
idea being the flashing neons drive the LDRs in the filter circuit and
I get a LFO output too. The neons and LDRs came from some old HP lab
gear, so I figured they should be fine. One is, but the other isn't,
which probably indicates a wiring error. I used 6021 sub-mini tubes
for the triodes and 6AU6 for the pentodes. The 'scope shot is from the
VCF that works, it sounds as nasty as it looks, I like it!

Electronic Peasant VCA/Mixer 2&3. If you have seen this design it is
the one with the 600:600 Ohm transformer on the output. It works
perfectly! I think I might try a few more EP designs

Power supply is +/-140V, but I will increase the output to ~160 or so.
heaters are powered by a switching PSU from a computer, just added a
pot to get 6.3V from it at 20A.
All sockets BNC, today I built an interface panel to send/rec signals
with my other synths.

cheers
Andrew