IGS Audio Alter 500 FET Compressor - Black

The ALTER is a single-channel unit with stepped input and output controls. The Ratio switch has six positions, including two additional to the original 1176 1:1 and 2:1 settings. Slam Mode can be turned on with a separate switch, working regardless of the Ratio settings. Attack and release times can be set to Fast / Mid / Slow with 3-pole switches. The compressor is equipped with a relay bypass, achieved on the front panel. The input is balanced with a modern, low-noise op amp and the output with a Carnhill transformer. The circuit has two amp stages, between which is the output control. The stage amps are based on the discreet API2520 circuit. 

Front panel, Notable features: 
Variable Attack - 3 ranges: 0.02, 0.2 and 0.8 ms. 
Release – Amp recovery time to the value of 0.85 max. Range: 50ms, 600ms, 1.5 sec. 
Ratio ranges: from 1:1 (line amp), through 4:1 (compressor) to 20:1 (limiter) 
SLAM - allows the enabling of All-Buttons-On - aka "4 button trick" 
GR - very fast LED indicator showing the compression level in the range from 0 to 30dB. 
Specifications: 

- API 500 standard Module, 
- Input impedance: 1kOhm, 
- Output impedance: 600O on Carnhill- Maximum input level: +20 dBu, 
- Maximum Output Level: +22 dBm, 
- Total Harmonic Distortion: 0.2%, 
- Frequency response: +/- 0.1 dB 20Hz to 20kHz, 
- Gain: 40dB- The signal to noise ratio: greater than 99 dB- Attack: 0.02, 0.2 to 0.8 ms, 
- Release: 50ms, 600ms, 1.5 s,