Hey guys. My amp has a problem. It is a Marshall Vintage Modern 2266 head. It keeps losing power. Well, volume. I can hear the guitar through it still but it's no where near as loud as it should be. There's obviously something wrong with it. My first thought would be the valves. But, despite it being a large amp, I haven't really turned it up past loud bedroom level, my band went tits up so I haven't used it at gigging volume yet. Ever. So I don't think it'd be the valves, seeing as I've only had it since March this year. There's no burning smell, smoke or anything out of the ordinary, just a significant volume loss.

I've taken all the pedals out and that doesn't make a difference.

I've also tried a different guitar, same result.
Hope you can help
Last edited by WholeLottaIzzy at Sep 22, 2011,
i'm guessing power tubes bro

tubes are funny like that

they can last 20 minutes or 20 years

you can try biasing the amp. does it have external test points? hit the tube pins with some contact cleaner and work them in and out. swap some preamp tubes around too while you are at it and report back
I have no idea when it comes to servicing or maintenance on an amp. Both valves are glowing, so that means they're working, right?
Oh. So it's definitely the power valves? So I just buy a new set (KT-66's) and put them in? Is it easy to do myself or should I get someone to do it for me?
the work itself is not too complicated but it can be dangerous.

every amp is different.

my amp is similar to yours and I have a blog on biasing 'my' amp which may or may apply to yours - but might give you an idea on what to expect.

no, no one can say that it is definitely your power valves - especially over the internet.

you might also try asking on the marshallforum