Originally released in the 70's, the API 525 is a "feedback" type
compressor, such as the 1176 and 660, etc. An input (threshold) control
and output (make-up gain) control are provided. An additional "Ceiling"
fine tune function modifies threshold and
make-up gain for
precise changes in compression without changes in output. A
compression/limit switch sets ratio at either 2:1 or 20:1. Attack time
is as fast as 15u/s. Four auto release modes are offered via two
switches, 0.1s, 0.5s, 1.5s, & 2.0s. A De-Ess function inserts an
inverse vocal energy curve filter in the detector for effective
sibilance/p-pop reduction. The 525 is an identical re-issue of one of
the most popular API products ever.
The API 525 is perhaps the most successful solid state feedback
compressor in history. It delivers dynamics control behavior unlike VCA
"feed forward" compressors so common today. A remarkable multi-function
"ceiling" control can increase gain reduction (lower threshold) while
simultaneously raising output level to match, so the user can alter
dynamics "on the fly" without level changes. This re-issue design has
been taken from the original blue prints and spec control drawings from
the API archives.
Release times vary with frequency, with high frequency/full
bandwidth content released faster than just low frequency for natural
envelope tracking. Attack time is fixed, chosen to catch the fastest
peaks, without "pumping". Equally useful as a tracking, mixdown or
program compressor/limiter, the benefits of the API 525 are most
obvious to those who use compression on a regular basis. "Vintage"
dynamics control, an easy to use multi-function control set, and a wide
range of 500 Series mounting options assure that the 525 will surpass
your most critical applications. With the addition of a hard-wire
bypass switch, a balanced input, and a pinout that is the same as all
the other 500 series modules, the 525 is still, after 25 years—"the
sound". Two or more 525s can be linked for multi-channel compression.
The 525 Feedback Compressor/Limiter makes use of the 2510 and 2520
op-amps and therefore exhibits the reliability, long life, and
uniformity which are characteristic of API products.
- Reissue of API's original 525 from the early 70's
- Peak detecting "feedback" compressor/limiter
- Variable Threshold and Output levels
- Unique "Ceiling" control combines key functions
- VU meter for monitoring gain reduction
- 4 Switchable release modes
- De-Ess function
- Traditional API fully discrete circuit design
- Hardwire bypass