OT - Tube buzz / Amp question!?

[spkirby]

Folks,

I have recently picked up a tube amp that produces a buzz / fizzy rattle when I hit the open low E string on the clean channel when the volume is loudish. I thought this would be a preamp tube issue so I've just ransacked my other amp for 12AX7's as test replacements but this (tube?) rattle/buzz is still there.

Is this problem also often seen in power tubes? Or could it be something else?

Just wondering as I dont have any like for like power tubes to allow a full test so I am wondering what you guys may have experienced in the past....?

Thanks
Steve

 

[spkirby]

As an addition...just tested the combo amp by routing it to an external speaker (and detaching the built in speaker). Now no buzz...

Hmmmm power tube, loose component....??

 

[TNT]

Tubes that are typically "failing" produce odd & unique sounds that are prevalent throughout the entire scope of notes/strings.

I would probably say that it is a "vibrating" issue somewhere with either guitar, amp, amp stand, things nearby, etc. . . .


Frustrating though - good luck!

 

[candid_x]

Could be any number of things in the cab. My first guess would be tube sockets, which are usually held in place with pop rivets. Often the rivets are loose and rattle at certain frequencies. Just a couple of amps which are notorious for this include smaller Fenders and Peavey Classic 30's. Not hard to fix, either by tightening the rivet or with a small dab of silicone. Also check your reverb tank, if it has one, and loose speaker mounting screws/bolts.

 

[Spudmurphy]

You could try tapping gently with a pencil on some of the components to see if that induces the same fault?

 

[spkirby]

After a bit more experimentation I have concluded it is the EL34 power tubes rattling, one in particular. Playing the open low E on the guitar while simultaneously holding the EL34 with a oven gloved hand (dont try this at home kids!) reduced the rattling considerably.

I guess it's time to cough up for a new pair of EL34's...

 

[Larry]

It could be the EL34 tube. Or the tube socket could not be holding the tube securely. Check both