rattling sound coming from g****r amp?

[budget bassist]

I know it's not a bass amp, but I thought you tech-heads might know. I bought a little 20W ashdown valve combo used from a local music shop a couple of months ago, and today it's started making a little rattling sound when playing, or if i tap the amp lightly... It's pretty irritating, and it's coming out in recordings as well. It only makes the sound when the amp is on, not on standby or when it's off. Any ideas? I thought it might be a loose valve or something, but seeing as it doesn't happen when it's off, it may not be?

EDIT: sorry i just realised this should probably be in technical issues, feel free to move it, mods.

Edited February 5, 2011 by budget bassist

[GarethFlatlands]

Loose spring reverb unit?

[budget bassist]

Hmm possibly, i'm not entirely sure if it's spring reverb or not


EDIT: yeah i think it is

Edited February 5, 2011 by budget bassist

[RAY AGAINST THE MACHINE]

It is a guitar your using? If not, you could've blown it .

[budget bassist]

yes it is a guitar

[Mr. Foxen]

Microphonic valve. Tap them with a chopstick when it is on. Is most noticeable if it is one early in the signal path, as there is more gain afterward, so if you have no spares, can do some swapping to lessen the problem.

[budget bassist]

[quote name='Mr. Foxen' post='1117142' date='Feb 5 2011, 10:25 PM']Microphonic valve. Tap them with a chopstick when it is on. Is most noticeable if it is one early in the signal path, as there is more gain afterward, so if you have no spares, can do some swapping to lessen the problem.[/quote]
cheers, i'll give that a try

[GarethFlatlands]

Tap all your valves with a glass hammer. If they smash, they're a witch.

[budget bassist]