March 13th, 2012, 09:20 PM
I am just finishing up a 5F11 clone all is working well except I would like to slow the vibrato speed down.I would like to get it as slow as my 6G2 Princeton. I have tried adding resistors to ground on the 2meg speed pot and at 5 meg total resistance it is slow enough but won't get much faster when turned up. Will changing the cathode resistor to a 3.3 K ohm like the oscillator triode is biased in a 6G2 affect the speed of the oscillation ?
March 13th, 2012, 10:38 PM
Correct me if I'm wrong (please cause it won't be the first time!) but I thought the best way to control the tremolo speed range is via the capacitor set up in that circuit.
I would put the resistor network back to stock and then from memory try doubling in value one or more of the capacitors (eg 0.01 to 0.02) in the tremolo circuit and that should slow it down for you.
March 13th, 2012, 11:00 PM
I built a couple of these amps and definately the caps for speed. If you want to just experiment keep the .01 in and tack another .01 on top of it just to hear the difference, but that was the trick for me and i like to get it as slow as it will go.
March 13th, 2012, 11:16 PM
Thanks Gentlemen I will try that right now.
March 14th, 2012, 12:00 AM
I returned the resistor /pot to stock and replaced one of the .01 caps with a .02 it gets slow enough now but when I turn the speed up it cuts off at about 11 of 12 as if the tube is oscillating into cutoff. I have a decade box I think I will try a .015 as a substitute. Capacitance is definitely the key to the problem though ,Thank You both very much