Vintage Bogen Acousta Master CT-60 PA Amp

I tested the unit with a Shure SM57 microphone and both an 8 ohm and 4 ohm speaker cabinet. It works as it should. The built in compressor also works really well. It is an older unit so the pots should probably be sprayed out to eliminate some very minor crackles.

Bogen Acousta-Master@ CT Series Public Address Amplifiers are versatile, silicon-transistor preamp-mixer/amplifiers designed for professional-quality sound reinforcement requirements.

Model CT-60 is rated at 60 watts,

Four high-impedance microphone inputs are provided, each convertible for use with low-impedance microphones.
A simple modification converts inputs to low-impedance unbalanced; balanced inputs require accessory plug-in
transformers. Two mic inputs and one auxiliary input may be remotely controlled or muted for announcements over another mic channel. The same two mic inputs may be converted to accept a magnetic source, i.e., turntable or tape player. Two auxiliary inputs with fader control are provided, as well as a bridging input.

Acousta-Master amplifiers feature the Bogen built-in acoustic equalizer filter circuit, which provides a means of
boosting or attenuating any of five selected frequencies to suit individual room acoustics. An electronic limiter circuit provides uniform output regardless of wide variations in the input level. With this capability, all paging calls can be transmitted with the same volume and clarity. An output terminal strip and connectors at the rear of
the amplifier provide standard speaker impedance taps, as well as connections for 25volt or 70-volt balanced lines.
There is also a bridging output for feeding a tape recorder. Bogen accessories provide the amplifier with telephone
line input and output connections, remote volume control, and channel override facilities. Further information is
contained in the Accessories section.

The amplifier operates from a 105-125 volt, 50/60 Hz source. A three-prong line cord provides automatic grounding when connected to a three-wire power outlet. The power line is protected by a circuit breaker, and the output transistors by a thermal overload device, which shuts off the unit when the temperature of the heat sink rises excessively.