API 525 Discrete Compressor / Limiter / De-Esser Re-Issue - 500 Series Classic Module


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Dale #:API-525

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  • 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.

    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.

    • 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
  • Input Impedance> 30 K Ohms, Balanced
    Output Impedance100 Ohms, Transformer coupled, Balanced
    Operating Levels-15 dBu to +20 dBu
    Maximum Gain Reduction25 dB
    Noise98 dB below +10 dBu output, at 10 dB of Compression
    Harmonic Distortion0.5% Max, 30 to 20 kHz
    Attack Time15 micro seconds
    Release Times.1, .5, 2.0, 2.5 seconds
    De-essingInversion of the Voice Energy Curve
    SlopesCompression, 2:1, Limit, 20:1
    MeteringCompression or Limiting-Illuminated Analog dB meter, shows Gain Reduction
    Frequency Response±.5 dB, 30 to 20 kHz
    Power Requirements±12/18 Volts/DC, @80 ma.
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