Ibanez SG655 making speakers thump.

[string45]

On occasion, my Ibanez SG655 will make the speakers of my Baby Mark IV combo amp, push in & out to the point of making a loud thumping noise without me touching a string in active mode.The other night it did it when a turned the mid knob more then halfway & got worse the more I went. This bass also seems to have way more output then it should in active mode. Any idea what's going on?

 

[Keither]

Hey there, maybe you can find a very small volume trim pot in the electronic cavity, sounds like its cranked up.
If the trem pot is there you can adjust with a small screw driver.
The pre amp should be capable of matching volume with passive mode.