could this be a leaky cap?

[jamme61]

The amp sounds ok but as it gets hotter the sounds starts to die. The sustain on the note gets worse and worse until it sounds very weak and the bass part of the sound starts to break up like a fuzz pedal sound. The longer I play the amp the worse it gets. I changed all the preamp and power tubes out- it only does this on the crunch mode all the other modes sound strong.
checked the effects loop - in or out same problem. The amp is a Mesa Boogie stiletto that I picked up used -its a stage I - very early one 2004 dont know the history of the amp. thanks for any help on this

[herbvis]

Does this happen in all modes? Tube Rectifier and diode mode. Bold and spongy mode

[jamme61]

yes it happens in all those modes too ( Tube Rectifier and diode mode. Bold and spongy mode) I'm a plexi guy and this amp is very complex - hard to sort out. I have all the schematics- its funny it was sounding great and I was playing and I heard and felt something change - and like I said, the longer the amp runs the worse the problem gets. I'm going to pull the board next because there are mods done and maybe some of the soldering is off? anyway I know Mesa around here is a bad word so thanks for the time on this.


Update - turned out to be a bad Plate resistor- very happy

[herbvis]

Thats great! I love it when the problem found and corrected. I had a stilleto deuce mkII. A killer amp with all sorts of awesome options. Nice looking too! Maybe one day ill pick up another one. After I pick up another Vintage Modern, a Nice Twin, A nice strat etc, I can dream right lol! Anyways, great news! I am happy for you