After doinking around with far too many less important matters, I
finally finished the Dual Tube VCA/Wavefolder. Whew! Actually, the
only real hang-up turned out to be the tube selection. I had
purchased 4 NOS 6064's and did my initial testing and breadboarding
with, apparently, the best of the lot. What are the odds?
After playing around with other parts of the circuit, I finally put a
pot between the cathode and ground of each tube and tweaked the bias
for maximum effect and range. Now I have one VCA with only a drive
control and a make-up amplifier gain switch (selecting a gain of
approximately 2 or 4)and a second with the addition of a CV
level/screen bias control. In the future, I might add additional
make-up gain (perhaps a gain pot)and a zener clipper to hold the
amplitude to 10vp-p. That would add some extra rasp to the mixture!
A cool module, indeed, Ken! Thanks for the design. Next up will be
a 6JH8 beam modulator with 15VDC plate voltage. Now that the power
is available, why not? I'll keep you posted.
Chub
finally finished the Dual Tube VCA/Wavefolder. Whew! Actually, the
only real hang-up turned out to be the tube selection. I had
purchased 4 NOS 6064's and did my initial testing and breadboarding
with, apparently, the best of the lot. What are the odds?
After playing around with other parts of the circuit, I finally put a
pot between the cathode and ground of each tube and tweaked the bias
for maximum effect and range. Now I have one VCA with only a drive
control and a make-up amplifier gain switch (selecting a gain of
approximately 2 or 4)and a second with the addition of a CV
level/screen bias control. In the future, I might add additional
make-up gain (perhaps a gain pot)and a zener clipper to hold the
amplitude to 10vp-p. That would add some extra rasp to the mixture!
A cool module, indeed, Ken! Thanks for the design. Next up will be
a 6JH8 beam modulator with 15VDC plate voltage. Now that the power
is available, why not? I'll keep you posted.
Chub