Comptronic Optical Leveling Amplifier

Smooth program-dependent compression, from transparent leveling to saturated drive.

Comptronic is an optical leveling amplifier built around an optical cell. Its program-dependent attack and release produce gradual gain changes that work naturally across vocals, bass, synths, guitars and full mixes.

Peak Reduction controls how hard the sidechain drives the optical cell, while Compress and Limit provide two different compression curves. The response remains smooth even at substantial gain reduction, making it useful for everything from gentle leveling to more pronounced dynamic control.

The R37 Frequency Response control shapes what the compressor listens to: keep it frequency-flat for classic full-range leveling, or focus it increasingly on high-frequency content, so bass stops driving the compression and bright peaks get tamed instead.

The Analog trim adds tube and transformer coloration. Keep it clean at 0%, use the classic setting around 50%, or push it further for pronounced harmonic distortion and saturated low end.

A straightforward compressor with enough range to cover both transparent control and deliberate coloration!

Front panel

• Gain output level from 0–100%. 37% is unity gain, with a range from −25 dB to +28 dB.
• Peak Reduction controls how hard the optical cell is driven.
• Compress / Limit Compress provides a gentle ratio of approximately 3:1. Limit uses a steeper, flatter response.
• R37 Frequency Response 100% gives a flat sidechain response. Lower settings increase high-frequency sensitivity by up to 10 dB of additional gain reduction.
• VU Meter switch between Output, Gain Reduction and Sidechain level.
• Sidechain switch between internal and external sidechain.

Back panel

• Analog trim adds tube and transformer coloration from 0% (clean) through 50% (classic tone) to 100% (stronger saturation).
• VU Scale dBFS / +10 / +18. Sets meter sensitivity so 0 VU corresponds to 0 / −10 / −18 dBFS.
• Connections stereo audio input and output, plus stereo external sidechain input.