Vintage API 525 Pair

Original ’70s API 525 pair. These take a little getting used to, control-wise, but once you get the hang of them, they’re a really wild time. Very “colored.”

The input (threshold) and output (make-up gain) controls are what they say they are, along with an additional “Ceiling” fine-tune function, which can increase gain reduction while simultaneously raising the output level to match. A compression/limit switch sets the ratio at either 2:1 or 20:1. Attack time is fixed, chosen to catch the fastest peaks without “pumping.” A few release times are offered via two switches, which you can combine. Release times also vary with frequency, with high-frequency/full-bandwidth content released faster than lower frequencies for natural envelope tracking.

A De-Ess function inserts a filter into the detector for effective sibilance/pop reduction—also handy for bright things like cymbals or acoustic guitar finger-slide noise.

The original 525s are not “500 Series compatible,” so you can’t just plug them into a lunchbox. These have been modified to work with any modern 500 Series power supply.

These each use three 2520 op-amps, and the two that have actual audio running through them are vintage Huntingtons. The newer API op-amp you see is in the sidechain/detector circuit. This was done for reliability and to match the units more closely for stereo operation.

These came from Dr. Dre’s Studio Record One, founded by Val Garay in ’79. Not that that really matters, but it’s a fun historical fact.

Local pickup in Los Angeles. Free shipping if you’re in the US 48.