Heritage Audio 73 Jr. II, 500 Module, 80 dB Class A microphone preamplifier, Selectable input impedance, Ideal for ribbon microphones, 50 dB Class A line preamplifier, Discrete Class A J-Fet DI input with high input impedance, Class A single ended, 2N3055 output stage, 20dB pad switch, Phase reverse and low cut, Variable hi-pass filter 20 - 220 Hz, +48 V phantom power switchable, Output control, Carnhill input and output transformer, Construction: 500 modules