Tube Amp Archive

Thanks for the reply - the manual says this: 'Connect EXT AMP 1/2 only to amplifiers that utilize "short-tosleeve" footswitch inputs. Connecting to any other sort of input could cause permanent damage to both your amp and HX Effects hardware! If you're not sure if your amp has short-to-sleeve inputs...

I have a Musicman RD50 and want to be able to switch the limiter channel and reverb on and off with my Lien 6 HX FX. Does anyone know whether this will work with it or what sort of voltage the RD50 is expecting to see to change the channel?

Replacing some out of whack resistors helped. Replacing the IC's stopped all the oscillation - sounds great now and very low noise floor even with gain.

Sorry, I meant more of a noise than a hum after the resistor change. I have now changed the wire wound resistor to a carbon film resistor one and the amp is nice and quiet and no sort of oscillation/hum other than at absolute maximum volume and gain which I am unlikely to ever want anyway.

Well, I returned R61 to 47k stock. Now the hum/oscillation doesn't start until the master is almost fully cranked, somewhere I'll probably not need to use it at. But now I have HF noise, like RF hum. I had used a cheap ceramic wire-wound resistor - idiot! Decent film resistor on its way which I reck...

Hi - thanks for the help. The BobW mods can be seen here https://imgur.com/a/Q9Ao364 I have sen it suggested that the 1K substitution for 47k at R61 may be the problem and leading to too much plate voltage so I will put that back to stock first. There is no problem with the clean channel. As for mud...

Hi all, I recently re-capped my RD50 (Rev-B) I replaced all of the electrolytic capacitors. I upgraded C33&34 to 100uf, c35 to 20uf. I then did the BobW mods. The only other mods I have done are to bring the rest of the board to Rev E spec. That included diverting C23 to pin 2 on IC_2 from Pin 1 and...