HELP Flatulant Amp!!!!

[Robotalk]

I was playing a small gig today, and my Mesa Boogie F30 "quit" on me. I had it turned up louder than I usually do (around 1 o'clock) but I had taken the gain down, and I don't think this was the problem. All of a sudden, when I kicked my octave pedal on, the amp made an intermittent farting noise. BRRMP.....BRRRMP....BRRMP. I turned off the octave, and it went away, but then came back when I kicked my fuzz on (same pedal-Pigtronix Disnortion). I then turned off my amp, and plugged directly into it. It worked fine for a minute, then the same thing happened, on all channels. Someone had an old Peavey they let me plug into, and I had no trouble (amp or pedals-and I did use the Pigtronix) through that.

I retubed the amp (pre and power amp) with Eurotubes (which have been great) about a month ago. So, I'm unsure what the problem is. Anyone have ideas???

[andy7jem]

Indigestion??

[GuitarBizarre]

Sounds like the speakers have blown. The only other thing I know causes problems like that with speakers, is when the cabinet uses porting thats badly designed.

[Robotalk]

So here's an update. I played around with it at home, and even with the dirty channel around 9:00 if I really dug into chords the same thing would happen. When I used the channel switch on the amp, it would happen too. Then I tried changing power tubes, and everything worked fine, even when pushed. The power tubes were only 4 months old, so I'm wondering if it is something to do with the fixed bias of the amp??? Or did I just blow the tubes? (I only play about 2 hours or less a week)