Offering an exact reissue of the famed original from the early '70s, the API Audio 525 is a peak-detecting feedback-style compressor and limiter module for 500-series racks. Sporting variable threshold and output levels, an analog VU meter for monitoring gain reduction, and a unique Ceiling control, which combines key functions, the 525 is a versatile vintage dynamics processor.
The unit sports a compression/limit switch, which sets the compression ratio to either 2:1 or 20:1. The attack time is as fast as 15 μs and is fixed, in order to catch the fastest peaks and avoid the pumping effect. Four auto-release modes can be selected via two switches, and a de-ess function can be used to quash excessive sibilance and vocal pops. The 525 also features a hardwired bypass switch and balanced input and output. You can link two or more 525 modules for stereo processing and multichannel compression.