API 500 Series 525 Discrete Compressor Module, Re-Issue

API 500 Series 525 Discrete Compressor Module, Re-Issue

Product code: api525

The API 525 is an exact reissue of API's original 525 from the early 70's in Series 500 'Lunchbox' format.


  • API 500 Series 525 Discrete Compressor Module, Re-Issue

    The API 525 is an exact reissue of API's original 525 from the early 70's in Series 500 'Lunchbox' format.

    Main Features

    • Peak detecting 'feedback' compressor/limiter
    • Variable Threshold and Output levels
    • Unique 'Ceiling' control combines key functions
    • Analogue VU meter for monitoring gain reduction
    • 4 Switchable release modes
    • De-Ess function
    • Traditional API fully discrete circuit design
    Read More

    Originally released in the 70's, the API 525 is a 'feedback' type compressor. An input (threshold) control and output (make-up gain) control are provided, along with an additional 'Ceiling' fine-tune function which 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. 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/pop reduction. The 525 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 lower frequencies 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 525 utilises 'vintage' dynamics control and an easy to use multi-function control set. The 525 has a hard-wire bypass switch, a balanced input, and a pinout that is the same as all the other 500 series modules. Two or more 525s can be linked for multi-channel compression.

    The API 525 Compressor makes use of the 2510 and 2520 op-amps and exhibits the reliability, long life, and uniformity which are characteristic of all API products.


    API 525 Specifications

    Input Impedance: > 30 K Ohms, Balanced
    Output Impedance: 100 Ohms, Transformer coupled, Balanced
    Operating Levels: -15 dBu to +20 dBu
    Maximum Gain Reduction: 25 dB
    Noise: 98 dB below +10 dBu output, at 10 dB of Compression
    Harmonic Distortion: 0.5% Max, 30 to 20 kHz
    Attack Time: 15 micro seconds
    Release Times: .1, .5, 2.0, 2.5 seconds
    De-essing: Inversion of the Voice Energy Curve
    Slopes: Compression, 2:1, Limit, 20:1
    Metering: Compression 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.
    Size: 1.5 x 5.25 x 7.5 inches
    Weight: 1.77 lbs.



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    UK Non-Mainland: £ 12

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  • Additional Information

    On demo in store No
    Brand Api
    Condition New