I got an artisan 30 combo second hand. Played for 3 hours at the shop and loved every minute of it so decided to trade in a guitar and money on top for it. Because of this i didn't get a warranty.
I have been using the amp for no longer than a few weeks with a Blackstar HT Overdrive (the one with the valve and different power adaptor) and various other effects. When playing along with some tunes through my studio monitors the sound of the amp cuts dramatically and there is a loud 'hum'. When i switch the amp on stand by there is an awful noise which kind of sounds like a wave crashing/waterfall. I sent it to a local Amp servicing guy who only managed to get the amp to do this issue only once (he thinks) after turning the amp on/off roughly 100 times. He didn't notice anything wrong with the wiring etc but did notice that one of the EL84 housing brackets got extremely hot. He replaced all my EL84's in the hope the issue would stop. Needless to say it hasn't stopped and happened again. So my questions are:
Could it be related to the Overdrive Pedal?
Could it be because of my Monitors?
It only seems to happen when im playing along with music, but cant see why this is an issue, its not effected any other amp i have owned.
Its also worth noting that when i had everything hooked up to the amp (OD Pedal & other various pedals) with the amp on stand by i 'blended' the two channels and got a slight electric shock.
Please help, any advice or assistance would be massively appreciated