V571 Compander / Dual VCA

Description

The CoolAudio V571 is a compander noise reduction chip, but it contains two VCAs which can be used independently. It is a modern replacement for the SA571 and NE571. The chip is very useful to squeeze a bit of extra performance out of BBD-based circuits like delays, chorus, or flangers. It can also help reduce noise in PT2399-based delay circuits.

There is a short article about compander noise reduction with schematics for the compressor and expander stages that you might find helpful.