iD5751 compressor is based on the vintage unit made by the PYE company. This is a very interesting and unusual compressor. At its core, it has something called PWM - pulse width modulation. When compressor is working, it chops the audio signal and removes some bits of it. We don't hear these «chops» because the audio is cut at a very high frequency. Our ears translate this to a lower overal volume level. Finally, special filters remove all high frequency artifacts competely.
This compressor is rarely recreated. And there is a reason to this. The main PWM oscillator includes a special inductor, parameters of this inductor are not available anywhere. Often people make a PWM oscillator using a special chip – the circuit is simpler and easier to adjust. However, our research showed that a chip based PWM oscillator behaves differently in this particular circuit. As a result, the compressor sounds not true to the original.
Our module uses a proper inductor based PWM oscillator. This makes our compressor behave and sound closer to the original unit.