My shuttle 6 is acting up
 

Every once in a while, when I turn the power switch on on my shuttle 6, I get a very strange crackling noise accompanied with "a fm-radio off tune'' noiselike distortion. Today it happened again and I even noticed a large displacement of the speaker like I never saw it move before while playing through it.

I tried different kettle cords, with or without aux in, tuner out ; also with both of my 112 cabs (one has a speakon connector genz benz built in and the other has a speakon cable) . My luthier tried cleaning the jack inputs (all of them, including the fx loop) with a special tool. But the problem still persist.

Now I'm reading here that it could be a faulty tube in the preamp section... I have no idea on how to check and replace the tube, I don't know where to look for them inside the amp, I don't know which screws I have to remove to access or whatever, and I'm not sure on which tube to buy. I wrote to Genz Benz a few month ago, but I haven't heard of them. Could anyone guide me in the procedure ? I suppose I could bring the amp to a technician but I would prefer to learn how to do it in case it is needed again in the future.

I haven't seen anything from you. Perhaps you could PM me and I will walk you through a few troubleshooting steps to identify the problem. It may be nothing more than a defective tube, if so I will walk you through replacing that as well.

Yeah, some spam filters classify my email addy as spam. You, Sir, have a pm coming your way...

Good to see someone knowledgeable jump on this so quickly. Good deal, Andy!

As usual.

Tubes are easy. Unbolt the lid, spot the tube, pop it out, pop the new one in the socket, done.

Responded. We have some pretty agressive spam filters in place, otherwise life would be pretty miserable and my delete button would get worn out in a hurry ;)