I finally made a speaker cabinet that sounded so good with the GM40 that I was inspired to noodle away for hours…and then a weird noise showed up (like a high pitched fly buzzing). I shut down, played the next day and it came back after about a half hour. I popped the top and tapped the tubes and it crackled when tapping the shielded tube 12ax7 and the two right hand power tubes when facing the amp. Of those two EL84s, the second one from the right was dim. Also the two center TSC lights were lit. So I bought a new set of four matched power tubes and put them in. Tapped them, no crackle! Played for a while and no weird noise has shown up. The problem is the two center TSC lights are still on. I tried swapping the pairs around with no change. I tried a master reset, no change. I also swapped out all 3 preamp tubes with no change.
The amp seems to work absolutely fine. The volume drops from 40w to 20w on the power soak, it seems as loud as it did before it went wonky. I am guessing all the power tubes are working? I did the pick trick and all the tubes are within a flash of each other.
Any suspicions as to if there could be an underlying problem or if anybody has experienced this?
Thanks all!
(PS this amp is out of warranty so return is not a solution. I have used it sparingly because it never had a tone that inspired me but I loved the midi features. This forum got me to try different speakers and cutting the presence control as mentioned in thread “GM40 High End and Treble”)
The amp seems to work absolutely fine. The volume drops from 40w to 20w on the power soak, it seems as loud as it did before it went wonky. I am guessing all the power tubes are working? I did the pick trick and all the tubes are within a flash of each other.
Any suspicions as to if there could be an underlying problem or if anybody has experienced this?
Thanks all!
(PS this amp is out of warranty so return is not a solution. I have used it sparingly because it never had a tone that inspired me but I loved the midi features. This forum got me to try different speakers and cutting the presence control as mentioned in thread “GM40 High End and Treble”)