IGS A-Type 525 compressor/limiter

Compact design while maintaining all classic compressor features
 
The IGS A-Type 525 compressor/limiter is inspired by a legendary American design from the 1970s. The circuit is built entirely with discrete components in a through-hole assembly. The compressor input is balanced by the SSM2141 op-amp, while the output is transformer-balanced. An additional, second audio transformer is responsible for the feedback signal, which, after adjusting the time constants, returns to the compression control element, the VCR (Voltage Controlled Resistor). The control signal has a negative value relative to the circuit ground, and its value directly affects the VCR resistance, which in turn adjusts the gain of the first amplification stage.

Reissue of the original American "feedback" compressor with fully discrete design and balanced input/output.
 
Simple and fast operation thanks to the intelligent Gain control system
 
The compressor is equipped with a unique set of controls, including a „Compress” switch that simultaneously changes both Gain and Threshold values. This allows you to adjust compression parameters while maintaining constant peak signal levels. Additionally, separate Threshold and Output knobs allow for precise control over the compressor’s activation point and output signal.
 
Features variable threshold, output, and "Compress" control for dynamic adjustments without level changes.
 
Ultra-fast attack for perfect peak control
 
The device offers two modes of operation: Compressor (2:1) and Limiter (20:1). The Attack time is fixed and very fast at 15μs. The Release time can be set to one of four options: 0.1s, 0.5s, 1.5s, and 2.0s. An additional mode is the de-esser, designed to reduce sibilance in vocal recordings.
 
Offers fast attack (15μs), four release modes, and a De-Ess function for reducing sibilance in vocals.
 
Applications
 
The A-Type 525 has a wide range of applications. It works exceptionally well on vocal tracks, acoustic and bass guitars, various percussion instruments, and many other sources.

Bullet: Suitable for tracking, mixdown, or program compression, with hardwire bypass and multi-unit linking capability.
 
 
Input & Output
Audio transformersYes, IGS custom transformers
Input Impedance (balanced)10k, SSM2141
Output Impedance (balanced)75 Ohm, IGS custom transformer
Levels
Operating Level+4 dBu
Max input level+27 dBu
Max output level+28 dBu
Max Gain Reduction-25 dB
Max. gain25 dB
Noise Level-99 dBA
Time constants
Attack15us
Release100ms - 2s
Ratio2:1, 20:1
Bandwidth
Frequency response8 Hz to 20 kHz, +/- 0.1dB
Distortion (@ 20 Hz - 20 kHz)
THD+N0.014%
Power
Power consumptionPower consumption: 2.5W
Packing box
Shipping weight1kg