Express 5:50 1x12 combo noise problem

When I play a power chord on my express 1x12 combo as the chord sound fades I hear a noise best described as a set of keys rattling on the amp . Has anyone had this , do you know a fix for this or do I bring it back to the store ? I just brought it home a week ago and it was used but looked good so I'm a little disappointed .If I'm playing with a back-up track then I won't hear it but if I want to record it's going to be ugly .Does anyone run a 5:50 head and experience the same noise or other noises because I'm thinking of trading for a head .Thanks....John T

Hi there, check out the post just below "possible microphonic problem".

Your "jangling keys" description again sounds just like my problem with the aluminium 12AX7 shrouds vibrating.

It's quick to check and free.

It sounds like a microphonic tube.

Does this happen at 5w or 50w or both? Mine seemed to do something similar when I played certain 'D' or 'E' notes at 50w. I tightened up the main chassis screws on the top and took off the preamp tube covers and now the noise is still there a bit, but greatly diminished.

The fact that this happened at the 50w setting leads me to believe that it could be one of the power amp tubes, but when a similar thing happened while trying an amp at a music store, the repair guys took it apart and said that it was the chasis rattling and the tubes picking it up. I don't rmember how they fixed it.

I pulled the plug on the 5:50 express and brought it back , but in a feeding frenzy I bought a Lonestar head and before I could get out of the store I bought a matching Lonestar 4x10 cab and a Voodoo Lab amp selector to hook-up my other gear.....Thanks

I always leave my credit card at home if I am "just going to look around".

Have fun with the Lonestar.