Studio .22 reverb attitude

[soberskipper]

I'm new and would like to say Hi to everyone


I am cleaning up a Boogie Studio .22 (1st version) for a friend and have noticed when the Master is all the way up, the Reverb makes a horrible noise if I touch the spring holders, wires leading from the tank, or the inputs with my chopstick. Also makes the noise as the Master pot is turned. When I remove the reverb tube, it sounds fine with the Master dimed. I have tried all the preamp tubes in my supply thinking it might be a shady tube but they all do it. Also, have replaced the 6BQ5 set just to see.

When I back off the Master a bit, the reverb is useable and sounds great.

There is a single, very small diameter (maybe 26 gauge? it's super tiny) leading from the middle spring to *nothing*... I can't tell if it once was connected to something but I can't find it on the schematic. I'm thinking it might connect to one of the other springs?

I read the manual and understand the part about how they say that the circuit is basically unstable in certain conditions... is this just how the reverb behaves with Master on 10?

Does anyone know if this loose wire could be the cause of my problem?

thanks,

uri g.

(this was posted at ampage too)

 

[stomper]

Do you mean by "horrible noise", a howling, feedback type sound? If yes, try swapping in another reverb tank. The tank gets bashed about in the caliber chassis. Try using adhesive weather stripping above and below the tank. Guard the tiny green and black wires from impacting the chassis. You followed a good practice of troubleshooting by pulling the reverb tube.
Stomper

 

[soberskipper]

The noise sounded like cymbals crashing mixed with "electronic" sounds... Since I've put the cleaned amp back into the combo box, It doesn't make that noise under those conditions... but it does start feeding back a low signal when I crank the Master and Reverb pots together.

Possible that exposure to RF in my room was the cause of that noise? (That room is bad for radio being picked up by the guitar) And having the slab of wood above sensitive reverb wires is quieting it now? Just a thought.

thanks for the tip about the weather strip too!

 

[stomper]

If you were running the amp outside the cabinet, the open chassis was not sheilded and could pick up the noises you describe. Especially if someone nearby had a cell phone in use. The design of the early caliber amps was susceptible to reverb problems. That is why they put the tank in the bottom of the cabinet later on. The weather stripping is great if you gig a lot and want the reverb working when you get there!

 

[soberskipper]

lol

awesome info, thanks!