I have an MC420B and when using wired to motorcycle battery the sound will break up really bad when I accelerate but will work fine at idle or not under acceleration. I was thinking of using an external battery to take it off of the motorcycle charging system. Does anyone know what mc420b draws in power so I can get the smallest 12v battery that could power the unit and would last approximately 1 hour of usage?
Be sure to make sure that TA is turned off and that Standby Mode is disabled. Those are the issues I had that caused similar problems.