Analog tape compression circuit
This circuit is a waveform compressor that compresses more at higher frequencies. It consists of a 70 microsecond (2.25 KHz) pre-emphasis, followed by a diode type waveform compressor, followed by a 70 microsecond de-emphasis. This compressor has an unusually good sound considering the lack of time constants. Distortion and "pumping" effects are both virtually inaudible.This circuit was designed to simulate the effects of analog tape compression. It will be useful with digital tape recording equipment if a more "analog" sound is desired.
Notes for this circuit:
1. Power supply is a split supply of +/- 15 volts.
2. Any decent quality op-amps can be used.
3. If equipment feeding or being fed by this circuit has any extraneous DC voltages, you will need to add blocking capacitors.
4. The germanium diodes are available at Radio Shack, 276-1123.
5. The silicon diodes designated "1N914" are available at Radio Shack, 276-1122. 1N4148 diodes may be used.