The 100VAC output from the amplifier might destroy the emitter-base diode of the transistor when the peak of the signal goes 140V negative.
The transistor will be turned on only for the loudest signals from the amplifier.
Place a diode from emitter to base. Cathode to base, Anode to emitter, This will protect the transistor.Hi audioguru thanks for your input so what do I have to do?
The circuit I see will trigger on sounds greater than about 1/10 watt. If it is too sensitive, use a 10K potentiometer from emitter to base (instead of a fixed 10K.)The transistor will be turned on only for the loudest signals from the amplifier.