Blues Jr. Reverb Buzz

[sgsnider]

Hey everyone,

I'm hoping someone may have experience with this issue.

I have a ('95? Green Board) Blues Jr. that I purchased used about 2 years back.

After a short while of owning the amp the reverb went out. About 6 months ago I finally replaced the reverb tank with a Ruby reverb, at the same time changing my pre and power tubes (Blues Forever Set from Torres Eng.)

My problem is that whenever I turn up the reverb dial, i get this buzz that gradually gets worse as I increase the the amount. With the dial all the way down, there is no buzz.

I haven't been able to figure out why this is. A grounding issue? defective tank?

Any help would be much appreciated.

Thanks for your time!

[Prairie Dawg]

Hey everyone,

I'm hoping someone may have experience with this issue.

I have a ('95? Green Board) Blues Jr. that I purchased used about 2 years back.

After a short while of owning the amp the reverb went out. About 6 months ago I finally replaced the reverb tank with a Ruby reverb, at the same time changing my pre and power tubes (Blues Forever Set from Torres Eng.)

My problem is that whenever I turn up the reverb dial, i get this buzz that gradually gets worse as I increase the the amount. With the dial all the way down, there is no buzz.

I haven't been able to figure out why this is. A grounding issue? defective tank?

Any help would be much appreciated.

Thanks for your time!

Is your guitar well shielded?

[Enzo]

OK, if you spin the reverb control from zero up to full on, does your hum instantly come up with the control movement? Or does it take a few seconds to sort of build up?

Is the hum sound the same sound as if you touched the tip of your guitar cord? Or is it more of a low pitched WOOOOOO sound?

[sgsnider]

Hey Thanks for the quick responses,

Prarie dawg, I'm not really sure if my guitar is well shielded. I'm using a shielded cable (I think...). It's a telecaster made from parts by someone other than myself, so it is possible that that has something to do with it, but when using my guitar on other amps I don't seem to get the same problem.

Enzo, it instantly gets louder as I increase the reverb knob. Also, it is more like the guitar input buzz (although not as dramatic as that), rather then a "Wooooo".

[Enzo]

OK, real hum then, not pan feedback.

Pull the cables out of the jacks on the pan. Turn on the amp with the reverb up some. Now touch both cable plug tips with a finger. One of them should make hum out the speaker when touched.. that one should be plugged into the OUTPUT connector on the pan. We want to make sure the cords are not reversed.

Pull your pan out, and check inside it. Any broken little wires between the transducers and the jacks?

Measure DC resistance across each jack. (No cables plugged in) One should show a very low resistance, and the other maybe 100-200 ohms. WHat we don;t want to see is an open reading.

Plug the cables into the pan, but leave the pan outside the cab. Get the pan as far from the power transformer as the cables will allow. Does it make any difference out there? Does moving the thing or rotating it make any difference?

Since your pan is not the original, look closely at the two jacks. The OUTPUT jack should be grounded to the metal reverb pan chassis - the metal box itself. The INPUT jack shoult NOT be grounded to the pan chassis. Or using an ohm meter, measure resistance between the outer parts of the two jacks. If they show continuity between them, it is the wrong type pan.

[emtjr928]

Green Board Reverb

See if this info from BillM fits what you are experiencing.

Billm Audio Improving Blues Junior Jr Green Board Reverb