Blues Seville A note buzz

[bkemker]

I have a newer model Fender Blues Deville 212 and there seems to be a buzz every time an A noted is played. Have checked tube plates, reverb unit, speakers and anything else that can vibrate but have came across nothing. I have even used multiple guitars to see if that was the problem and still nothing. So I am kinda stuck and wanted to know what might be causing it.

[Enzo]

Roll up a magazine and hold the resulting tube to your ear. Now while someone plays to make it buzz, use the magazine like a stethoscope to listen to small areas at a time to determine where the buzz comes from. It is surprisingly directional.

Make sure all hardware is tight, including things like transformer mounts, handles, corners. While it does it, press hard against various surfaces of it - the sides, the top, the rear panels. Reach in and press against the baffle board between the speakers. Does pushing on anything stop it? Use the top handle and rock the amp tack at a 45 degree angle, hold it balanced like that. Still buzz? Now up on either bottom side edge. We are trying to put a bit of gravitational force on the cab, flex it a hair.

Up top, the panel peeks out from under the top surface. Get a small screwdriver or something and wedge it in the crack up under the top. ANy change?

There is a rear panel covering the chassis. REmove it. WARNING: the voltages inside this amp can KILL YOU. ANything loose on the inside of that panel? From the main board there are some gray ribbon cables down to the tube socket board. Make sure none of those are leaning up against the rear panel. Does the amp still buzz with that panel removed?

[Mick Bailey]

Just a check - if you plug your guitar into the 'power amp in socket' does it still vibrate? You isolate the preamp by doing this. If it stops then you may have a bad solder joint or a mechanical resonance in a preamp tube.