Problem with Mesa Express

[Zephor]

Ok here's a crazy sound I'm getting from my amp.

Here's how I created this:
Amp: Mesa Boogie Express 5:50 1x12 Clean Channel
Settings: Drive 11 oclock, Tre, 10 Mid 12, Treb 12, Reverb 10 Volume 8
Guitar: Stratocaster EMG pickups. (happens on all guitars but its different settings)


The sound clip I included has 2 normal notes, then the problem note. The only problem happens on certain notes on certain settings. Any way I can figure out how to fix this? The mic I used is terrible. It's the huge slipping not the popping.

http://rapidshare.com/files/145321247/mesa.mp3.html

 

[Don]

I can't listen to this at work (they block it), but I can listen to it then try it on my Express tonight.

 

[nemesys]

Interesting -- it sounds like the vibration from some notes is causing a poor connection within one of the tubes, or even the amp itself, to become intermittent. I'd start by looking for a bad preamp tube...

 

[MrMarkIII]

Google "amp motorboating".
Then take it to a tech.