stereo / dual mono Zener compressor/ limiter

aggressive version

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Gem Audio Labs Preceptor Model-A

The Preceptor model-A (Aggressive) is a two-channel, class-A compressor/limiter. Gain reduction is handled by a discrete VCA design based on Zener diodes and bipolar transistors. There are 16 preciesly matched Zener diodes on board! The Gem Audio Labs Preceptor Model-A compressor/limiter looks right out of the early '70s. Its stepped knobs dole out satisfying clickage and its dual VU meters bathe your console in a warm yellow glow. Hand-built using premium parts, the Preceptor juices whatever you send its way with warmth and sheer size. if you were looking to add aggressiveness and color to your final 2-Mix. If you’re looking for a versatile, great-sounding compressor/limiter, give Gem Lab Audio’s Preceptor Model-A a try.

Inputs: Balanced XLR

Outputs: Balanced XLR

Ext. sidechain inputs: Balanced TRS

Signal transformers: Carnhill

Bypass: hard relay bypass

Input impedance: 2k5Ω or 10kΩ switched on the front panel

Output impedance: 50Ω

Frequency response: 20-22.000Hz

Maximum input level : + 21 dBu @ sensitivity +4 dBu

Maximum output level: +23 dBu

S/N ratio (A-weighted) : better than 85dBu

Meter: 0 to -20dB gain reduction

Signal path: Class-A, discrete

VCA: bipolar transistors biased by Zener diodes

Dynamic modes: Compressor, Limiter (Fairchild  660)

Speed modes: fast, medium, slow

Attack: 0,5ms – 60ms

Release: 25ms – 6s

External sidechain: YES

Sidechain filtering : OFF, 40Hz, 80 Hz, 120 Hz, 200 Hz, 320 Hz

Blender (parallel compression) : yes

PSU: internal

Fuses type: 230V : 630mA (slo-blo; 5x20mm) /115V :1,25A           (slo-blo; 5x20mm)

Power consumption: 70W

Dimensions (WxHxD) : 483x133mm (3U) x 245mm

Weight: 6,4kg


Subject to change without notice.


Gem Audio Labs (Generic Audio) Preceptor compressor limiter review

Difference between Preceptor Model-A and Model-T

The Model-A has a “Speed” switch that affects Attack and Release times. On the Model-T, the switch affects Attack only (and is labelled as such).


The Model-T sports an additional switch (not present on the Model-A): “Action,” which lets you choose between two modes – each giving you a different combination of threshold and compression knee. “Soft” gives you less pump factor and is useful for for complex material – mastering, for instance. “Hard” allows for more agressive pumping and is great for tracking, when you occasionally want access to stronger compression.


The Model-T’s “Soft” setting is optimized for complex material that requires a more finessed touch, such as film scoring or classical music recording and mastering. In case your were wondering, the “T,” in Model-T designates “Transparent.” The Model-A (“Agressive”), lacking this switch, exhibits the “Hard” compression characteristic, and is great for more agressive material such as rock and pop recording and mastering.