Single Rectifier Severe Humming

[brentalous]

So recently I've been experiencing some pretty awful amp hum in my Mesa Boogie Single Rectifier. I've always used JJ 6L6GC's inside, and replace them every 7-8 months, since my band is pretty active with live shows. But, lately I get an extremely loud buzz and amp hum that I've never heard before, even when my tubes would use to give me the crackle signal that they needed to be replaced. This is entirely a different sound and is so loud I have to switch it on Standby to even keep it under control.

Deeper tones seem to trigger the noise and sometimes I can even strum and it'll stop completely — strum again and boom, there's the hum again. Before I buy another pair of tubes, since these are only maybe 2 months old, I'm wondering if there's something else I should be looking at?

I'm not seasoned in amp repair, but I'm really good with electronics so if it's something reasonably simple I can verify whether or not it's the problem — I'd love to know!

Thanks for any help!

 

[screamingdaisy]

I've had power tubes do that before. Usually something has failed mechanically and is rattling around inside. Bass notes vibrate it and cause it to intermittently short. If you pull it and shake it you may be able to hear something rattle inside the glass.

Did you look in the rear to see if one is red plating when it's humming?

 

[vick1000]

Clean all jacks with Deoxit by spraying a cable end and working in and out. Yes, like sex with your amp. Wipe the cable off every few "thrusts" and respray. Let the amp sit afterward for about 30min so it can "recover" (deoxit drying time), before powering up.

 

[TRENCHLORD]

Clean all jacks with Deoxit by spraying a cable end and working in and out. Yes, like sex with your amp. Wipe the cable off every few "thrusts" and respray. Let the amp sit afterward for about 30min so it can "recover" (deoxit drying time), before powering up.

"recover" huhuh huhuh

 

[Old BF Shred]

By all means, swap out the tubes.
Even 2 month old tube can go bad. Are you sure you're buying tubes that are rated for Mesa's bias range? (most vendors will know what you need).
Under-biased output tubes will often hum just before failure. As screamingdaisy says, look for tube plates glowing red...not a good sign! :shock:

It could also be a bad preamp tube so it is always good to have a known good spare to swap out, one at a time, to see if that helps.

A leaky signal coupling cap can cause this too, since it's job is generally to isolate the power supply voltages from the signal path.
Let's hope not, but changing tubes is a relatively easy first step....
Good luck!