Mesa Express 5:50 112 rattle at high master vol settings

[Laxrappa11]

ive had this amp for a month, played about 5 gigs with it, but didnt get to really crank it up for the first time until last weekend. i noticed i had the master higher than i had ever had on the amp before, maybe around 1 oclock on both channels, and i got this overwhelming rattling noise when i hit an open chord. the sound guy said it was a bad tube. seems like it could be a power tube issue since it only is noticeable when the master is cranked up past midnight. any ideas?

[recto-robbie]

One way to see if it is actually a tube with loose insides is get the amp to make the rattle again and hold the end of each power tube until you find the guilty tube. They will be hot obviously so use a cloth or something and simply apply a bit of pressure as if pushing the tube further into the socket. Dont break anything!!!!! Good luck

[Don A]

Might be a microphonic pre-amp tube. V2 or V1 would be the usual culprit. They're all 12AX7s so you can swap them around.

Also, has the chassis ever been out of the cabinet? Boogies have a tension screw between the chassis and cab.

[Laxrappa11]

no i havent touched any part of the amp except the dials on the front. now that i think about it i actually had the fx loop with my envelope in it for the first time on stage, but it still made the rattling with the effect off. its true bypass too so im not sure how that would affect anything

[jaxonmills]

I had power tube rattle in a few tubes when I had an Express 5:50 fwiw. The store replaced them at no cost, rattle went away.

[Laxrappa11]

im almost positive thats what it is, ive been contacting mesa im hoping to work something out this amp is brand new this whole deal is really frustrating

[recto-robbie]

You should have no issue then,, my first Mesa, a F-50 had some rattling tubes. Called Mesa and told them my problem but made it clear that the rattling was horrible. Within a week or so I had new tubes delivered to my house free of charge.

[jaxonmills]

If there's a Mesa dealer nearby, they should be able to help you out, even if it's not where you bought the amp. I'm pretty sure they'll just charge Mesa for the new tubes, not you. They can also help you diagnose the problem.