Have you changed speakers?
Is this a 22volt unit that has been converted to 110v?
Are you using a transformer to convert it to 110?
Many speakers' impedance will drop when pushed hard. If your nominal impedance is dropping from 8 ohms to 5 or 6, that could be why???
Otherwise, check for a mild short in the speaker cables. At low loads, the system can operate but as voltage increases...
Is this a 22volt unit that has been converted to 110v?
Are you using a transformer to convert it to 110?
Many speakers' impedance will drop when pushed hard. If your nominal impedance is dropping from 8 ohms to 5 or 6, that could be why???
Otherwise, check for a mild short in the speaker cables. At low loads, the system can operate but as voltage increases...