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IGS Audio Tubecore 3U Mastering Vari-Mu Compressor

Original price $3,995.00
Current price $3,195.00
Symmetric transformer balanced stereo mastering compressor


The IGS Audio Tubecore 3U is a fully symmetric transformer balanced stereo mastering compressor. The structure is based on the typical vari-mu solution. Apart from the classic INPUT, THRESHOLD and OUTPUT controls it introduces switchable high pass filter in the sidechain, parallel compression (MIX knob), independent ATTACK and RELEASE switches and user replaceable tubes accessible from the back of the unit.

The Tubecore was designed as a studio mastering compressor. It is built using the 3U enclosure, which improves front panel clarity and makes it easier to replace tubes located at the back. The compressor allows you to work either in dual mono or mid/side mode (M/S). The Mode switch has two bypass positions – they both do the same, but IGS has added the second one for your comfort and quick A/B comparing.

The design of the Tubecore 3U is based on the ease of tube replacement. As a user, you can choose between a few types: 6N1P-EW – standard set of tubes, “standard” IGS compression, 6BC8/6BZ8 – tight, transparent, punchy compression, 6386 – legendary compression, by famous twin triode, 5670 – deep and dark tube compression. The User Manual describes in detail how to replace tubes, so it is quick and straightforward.

Every single Tubecore 3U is hand made with high quality, matched components (1% metal film resistors, Wima caps). It is equipped with 6N1P-EW NOS tubes and individually calibrated to give you the unique and unspoiled experience of one of the best vari-mu compressors in history. It is equipped with Carnhill and Sowter audio transformers.


  • Vari-mu Compressor
  • All stepped manipulators: 24 pole Elma switches
  • Sidechain HPF: 120Hz, 60Hz, Off
  • WET/DRY mixer: 0 - 100%, 4 dB step
  • MID/SIDE processing: OpAmp M-S encode/decode
  • Input Impedance (balanced): XLR, 600 Ohm, Carnhill balanced
  • Output Impedance (balanced): XLR, 600 Ohm, Sowter balanced
  • Operating level: +4dBu
  • Max input level: +22 dBu
  • Max output level: +22 dBu
  • Dynamic Range: >107 dBA (@ 1kHz, +24 dBu)
  • Max gain: +35dB
  • Max gain reduction: 20 dB
  • Attack: 0.1 - 30ms
  • Release: 0.1 - 4s
  • Frequency response : 20Hz to 20kHz; +/- 0.2dB
  • Signal to Noise Ratio: 87 dBA
  • THD: 0.12 %
  • THD+N: 0.15 %
  • IMD (SMPTE): 0.32%
  • Crosstalk: 82 dB
  • Voltage: 115/230V AC, 50-60Hz
  • Power consumption: 44W
  • Power supply: external
  • Tube set: 6N1P-EW, 6BC8, 5670, 6386