My L1 Model II has developed a popping noise with instrument (unbalanced) input. It does it whether the instrument is plugged into the base or T1 Tone generator. Microphone inputs do not pop. There is no cutting of sound as in other community inquiries. I have 2 B1 bass modules; disconnecting them does not change the behavior. Thanks
Not sure what you mean by microphone inputs, as it has only the 1/4" input. You may have a dirty input or trim knob. Try spraying some electronics cleaner into the input and on the trim knob. Work the trim knob back and forth for 15 seconds and work a 1/4" in and out of that jack a dozen times or so.