Mesa Roadster problem, 100w doesn't work properly anymore, 50w works

Hi all,

It has come to my attention that I get huge volume drops now and then.
It's probably something in the power section.
If I switch the channels to 50w mode on the back of the amp, it all works fine.

If I have it on 100w I sometimes get huge volume drops and then the sound is very thin and low volume.
It actually sounds thin as if the volume is barely opened up, which is normal behaviour for the amp.

What do you think? The strange thing is it actually comes and goes... so sometimes it works, sometimes not.


50 watt works totally fine.

Hmm, it could be a pair of power tubes are on the way out, do you have spares that you can swap in to test?