VibroVerb clone problems

[rutledj]

I have built a vibroverb clone and just have a few questions. When I compare my voltage readings to that of the schematic I find some significant differences. They seem to match at the PT and Output tubes just fine. The plate voltages on the preamp tubes are close but voltages around the reverb recovery tube and PI are off nearly 25v. Perhpas this isn't enough to matter?

Anyway, the problem I have is that when plugged into the normal channel I get a nice clean tone until the vol reaches around 7-8. At this point I get a very buzzy noise. Using the scope, I don't see this until after the summing resistors (220ks) in front of the PI.

On the vibrato channel, it is much louder (higher gain) at the same vol setting compared to the normal channel. Go much above 2 and the buzzing really kicks in.

Also, the vibrato ckt doesn't appear to be working. I don't get any tremolo effect at all.

Any suggestions would be appreciated.

Thanks
Rut

[Phil_S]

AFA the tremolo, it is essential to use a 12AX7 in that hole or it won't work. The plate resistance on a 12AT7 is too low. Sorry, can't really help much otherwise.