"Shaken light bulb" sound from amp?

[MikeMcK]

That's the best way to describe the noise I hear from this amp... like an amplified version of a dead light bulb when you shake it.

"Aha" I think, it must be a tube. But I've now replaced every tube in it and still get the same noise.

Any ideas?

[Ronsonic]

EL84s?

[MikeMcK]

Hi John, it is a metallic sound. I tried a couple of pre's, but they were NOS RFT's that I bought at the same time (maybe the same issue). I'll try another one or two...

Ron, the power tubes are EL84s; it's a Liverpool clone from Nik at Ceriatone. I have a couple of quads so I swapped in a completely different set.

[Ronsonic]

I asked because those have a famous tendency to rattle. Usually just the mechanical sound of the tube itself, but through the speaker when they do fail.

Best thing is to go tapping around and listening. tap on tubes, reverb pan, chassis bits. See that the speakers are secure and that nothing is laying against the frame and that there's no construction debris stuck to the magnets. Look for unused spring clamps or tube retainers.

The EL84s are still my first suspect.