Amp back from the tech, unluckily the problem persist.
He said he couldn't find the real cause of the noise, he just supposes that it may be some faulty integrated circuit on the board ( 6-pin things, maybe optocouplers?? )...
He did the bias of the power tubes, only positive thing is that now the amp sounds louder at less "knob" volume, so the noise is now a minor issue while playing.
He also did a test of the "old" preamp tubes and said they're fine and I can keep them as good spares if needed.
Tho I'm still experiencing strange things:
Turned the amp on, and it had almost no volume and no gain in all of the 3 channels. Turning the volume knob on the guitar would give me A LOT of crackling/oxid-like noise. Noise (fried like) was present and consistent. Swapped the v1 with a spare one and it got way better. (gtr volume knob ok, volume and gain fine).
Then i noticed the noise would be present also with a 100% wet on the fx loop, thus making me think about a problem on the phase inverter ( tube or anything??)... I was playing and then after almost 1 hour the amp volume dropped almost to 0, so I shut off the amp. After shutting off the power, I heard strange popping sounds from the cabinet for like 3 seconds ( discharging/faulty caps?!? - I'm sorry, I dont know what it could be, just wondering ). Turned it back on, and all I could hear from the amp was a 50hz hum. Swapped v5 with a spare one and the amp worked (for an hour so far).
All this is really frustrating, is it possible that so many new/not old tubes fail randomly like that and then work fine?! If it was every other component, would the problem get better/change just swapping tubes?
I'm really hoping the problem gets costant now, because I can't bring to a tech and stay there and play for 2 hours hoping the problem will happen. Problem is that the problem doesn't seem to get consistent in time...
And I can't rely on this amp to play live because of the shame it would cause if it shuts off during a show.. :mad: