B-52 AT-100 making vibration sound when palm muting or low notes

[Metal-Head-Dan]

Ok so my head is making a weird vibration noise when palm muting or just hitting a low note... I replaced the tubes trying to get rid of it and it did for all of about 5 mins till the tubes got warm - now would a bad connection on the board pick up a vibration lime that and send it to the cab?

[Chuck H]

Vibrations (or things that sound like vibrations) can be really, really hard to find or troubleshoot.

Try playing the amp through another cabinet to determine if the offending sound is electronic or mechanical. If it's electronic the other cab will make no difference. If it's mechanical vibration the problem should go away when playing through a different cab.

If it's your cab that's vibrating you would need to tighten all screws, check for gaps where panels meet, does grill material touch the cab in such a way that it could cause the noise, is there a logo screwed onto the cab and could it be loose or rattling on the cloth, etc...

If it's an electronic issue I would try replacing the tubes. If that didn't help I would send it in for service. It's a fairly recent model amp, is it still under warranty? If it is let the store and MFG work it out. That's a cheap, disposable amp anyway so you may even get a new one out of it.

[Metal-Head-Dan]

I think its in the head itself - I have it out of the box to try to pin point it and when I tap the chassis the noise stops but will come back quickly - I did replace all the tubes and that did nothing but make the amp sound better when it's working properly - I've got it on a Marshall 1960a cab - any thoughts?

[Chuck H]

It could be anything. A parasitic oscillation, a cheap microphonic capacitor, a mechanical ground becoming loose, a tube pin making intermittant contact, etc...

Take your guitar into your local mega guitar store (probably Guitar Center) and plug it into the exact same rig WITH THE EXACT SAME SETTINGS as you use. Does it do the same thing as your amp??? If yes that's your ass, you should have bought a better amp. If not then you should explore any warranty option. Trouble shooting this sort of problem for a novice or in a shop could litterally take more time in hours than the amp is worth.

[Metal-Head-Dan]

yea i know its not a great amp... im in the process of building a JCM800 clone all point to point... this is just a head to get me by the sound is more annoying then anything else... im going to go through the boards on this one to see if i can figure it out if not oh well im only out like 200 bux... if nothing else itll be a good learning process about the shitty boards they use specially with the caps and resistors to get different tones... just looking to see if anyone has had the same problem... if its nothing i can figure out im gunna junk the head and pull parts