IGS Audio ZEN - Zener Diode Mastering Kompressor

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What is the IGS Audio ZEN?

The IGS Audio ZEN is a stereo analogue Zener-diode compressor and limiter designed for mastering, tracking and stereo-bus processing. Its audio circuit uses 14 bipolar transistors per channel, with compression achieved using eight hand-matched Zener diodes in a feedback circuit. It is a diode-based design, not a VCA, optical, FET or Vari-Mu compressor.

Is the IGS Audio ZEN suitable for mastering?

Yes. IGS Audio lists mastering as an intended application. The ZEN offers stepped controls, stereo linking, adjustable attack and release times, sidechain high-pass filtering, compressor and limiter operation, transformer-balanced inputs and outputs, and hard-wire bypass. These features support controlled, repeatable adjustments when processing a stereo master.

Can the IGS Audio ZEN be used for mix-bus compression?

Yes. The ZEN can process a stereo mix bus, with adjustable time constants and stereo linking for stereo sources. Its sidechain high-pass filter lets you reduce the influence of low frequencies on the compression detector. The amount of compression and the resulting character depend on the input level, operating mode and time-constant settings.

Does the IGS Audio ZEN have a limiter mode?

Yes. The ZEN offers selectable compressor and limiter operation. In compressor mode, the ratio varies with the input settings rather than being selected as a fixed numerical ratio. The limiter provides an alternative operating mode, but the ZEN should not be described as a brickwall limiter or as guaranteeing a fixed digital peak ceiling.

What attack and release times does the IGS Audio ZEN offer?

The specified attack range is 8–100 ms, and the release range is 10–2,000 ms. Both attack and release have a switchable ×4 multiplier, allowing longer time constants. The controls are stepped for repeatable settings.

Does the IGS Audio ZEN have a sidechain high-pass filter?

Yes. The sidechain high-pass filter offers Off, 60 Hz, 90 Hz, 120 Hz and 240 Hz settings. It filters the signal feeding the compression detector rather than removing bass from the main audio signal. This can help reduce excessive gain reduction triggered by low-frequency content.

What is AMP mode on the IGS Audio ZEN?

AMP mode bypasses the sidechain circuit so the ZEN operates as an analogue line amplifier without active compression. The unit offers up to 36 dB of gain. AMP mode is different from hard-wire bypass: it keeps the active audio path in use rather than bypassing the unit’s processing circuitry.

Does the IGS Audio ZEN have transformer-balanced inputs and outputs?

Yes. The ZEN uses IGS Custom audio transformers on both its balanced inputs and outputs. The specified balanced input impedance is 10 kΩ, and the balanced output impedance is 75 Ω.

What are the key technical specifications of the IGS Audio ZEN?

IGS Audio specifies a nominal operating level of +4 dBu, up to 36 dB of gain and up to 35 dB of gain reduction. The published dynamic range is greater than 100 dB, the signal-to-noise ratio is greater than 90 dB, and the frequency response is 20 Hz–20 kHz within ±0.1 dB.

What connections does the IGS Audio ZEN use?

The ZEN has two balanced female XLR inputs and two balanced male XLR outputs for its two audio channels. These provide the analogue connections needed to integrate it with suitable line-level studio equipment.

Does the IGS Audio ZEN offer dual-mono and stereo-linked operation?

Yes. The ZEN can process two mono signals independently or operate with stereo link engaged for stereo material. It also provides separate hard-wire bypass switching for the left and right channels.

Is the IGS Audio ZEN a 500 Series module?

No. The ZEN is a standalone 19-inch rackmount processor in a 3U enclosure. It has an internal linear power supply and does not require a 500 Series chassis.

What mains power does the IGS Audio ZEN require?

The ZEN supports selectable 115 V or 230 V AC mains operation and uses an internal linear power supply. Before connecting the unit, check that its voltage setting matches your local mains supply and follow the instructions supplied with the unit.