RM20 speaker/tube issue

ricky · Oct 23, 2013

I am having an issue with an RM20 combo. When I use an external speaker there is no problem. When I use the internal speaker, it rattles the cabinet and I get tube noise, all tubes check out so I am wondering what might be rattling. Anyone had this issue? What could I have tightened up to fix this?

Jaded Faith · Oct 23, 2013

Not to sound sarcastic, but it sounds like you have something loose in your combo. Should be a very simple fix in less time than it took you to post this on here. Grab a phillips head screwdriver and check the following in no particular order:

- The four screws mounting your speaker
- The bolts securing the amp to the combo shell
- Any/all screws on the cab
- The handle screws
- The logo badge screws

ricky · Oct 29, 2013

tightened all the mentioned screws and there is still a tube rattle that is not there with an external cab. HOw would one tighten tube sockets? Would that be a possibility? A friend had this little thing that straightened all of the metal things on all of the tubes and the tubes all checked out. It just seems that when I crank it, something makes the tubes rattle and make noise.

Jaded Faith · Oct 29, 2013

The sockets are PCB mounted, there's nothing to tighten. Are the tubes physically rattling or are they amplifying a noise? Can you put a towel on your hand and stop the problem by touching the tubes when the problem occurs?

ricky · Oct 29, 2013

I love the towel idea! However, I am out of town and will be away from that amp until next week. I will let you know....
thanks Rob. You are a great resource to MTS!

Oregon · Oct 29, 2013

That's great advice on the tubes. I've had annoying cabinet noise in all tube combos. Ungh.... Best of luck to ya, and I hope you get the rattle noise settled.

Adding preamp tube sleeves might help if that's where the noise is.

ricky · Oct 29, 2013

How did you deal with the tube/cabinet noise?

Oregon · Oct 30, 2013

Tightening every screw to start. I've been surprised how much that helps. Cab rattle drives me bat#%*^ crazy.

Jaded Faith · Oct 30, 2013

Almost every combo I own or service (which is a TON) benefits greatly from occasional tightening of every last screw. From the speaker, to the handle to the rubber feet. I do this immediately to every combo I service and often use Locktite or clear nail polish as needed to keep things snug. It makes a world of difference. Do no overlook the from baffle screws too, particularly if the amp is ever a Fender.