Engl Special Edition problem (help me to diagnose)

[spycam]

Well,
i'm the lucky owner of Engl SE amp for something more than 2 years. I didn't change the tubes yet, i don't use it a lot, maybe just 1-2 times per week (usually) for like 1.5 hours or so.

During the last 2 rehearsals i noticed a strange thing that bugged me for like 3 times: the volume of the sound gets like 2 times lower than i'm playing and it get's back to normal after i clicked on pedal board's pedals for a few times, or once i just used the stand-by button to switch it OFF and ON and it fixed itself right away.

I'm not a pro at diagnosing such cause, but i thougth that this couldn't be caused by tubes (if it was time to replace them).

Can you help me diagnose what could be the cause of that or give me some advices?

Thanks a lot!

 

[guitarguru777]

Bad power tube possibly?

 

[bryan_kilco]

I'd check all the tubes. I had an incident with my Mark IV once at a show, and ONLY once....it just may have been the power in the venue?!?! But my volume during soundcheck cut drastically and I couldnt figure it out. Someone told me it could be a bad Master Volume pot....but the problem NEVER happened again. I did notice I had issues on that same side of the same stage a few times, but it was usually more like the power actually cutting out from the outlet.

 

[spycam]

I'm using power conditioner, don't know if it was some problem with power if i would feel it this hard