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HomepageOutboardDual Compressors › Gem Audio Labs Preceptor-A
Gem Audio Labs Preceptor-A
The GEM AUDIO Preceptor is two-channel (stereo/dual mono), pure analog (Class-A, discrete) dynamic processor, in which the gain reduction is made by a transistor in the differential amplifier circuit with Zener diodes stabilization.

POWER The common POWER switch. The amber light and panel meters glow when the unit is powered on.

BYPASS The bypass is a hard relay bypass. If the unit loses power, it will default to this hard relay bypass.

INPUT GAIN This switch lets You choose between HIGH or LOW input gains by changing input Z (HIGH- 2k5, LOW- 10K)

SIDECHAIN In the INT mode the Preceptor acts as a normal compressor sending main INPUT signal to the gain reduction stage. In the EXT position You can use another audio track (sending it to the EXT SIDECHAIN input on the rear panel) to control the volume of the main INPUT signal. This technique can really improve the quality of your music. There is another trick in the box. If the SIDECHAIN switch is in the EXT position and the EXT SIDECHAIN input does not receive any signal, then the Preceptor turns into a pleasant harmonic distortion generator. The amount of distortion depends on the Z and the INPUT switches settings. The larger the signal, the more distortion is in the processed signal (at extreme settings, it may be up to several % of THD). This is because there is no control signal and the circuit is driven.

LIMIT/COMP In the COMP position the Preceptor operates as a compressor with 2:1 compression ratio. In the limit mode its behavior can be compared to the famous Fairchild 660 limiter.

SPEED This switch allows to choose between three attack and release speed modes: “S” – slow mode, “M”- medium mode, “F”- fast mode.

ATTACK The ATTACK control (11-position gold contact switch) determines how fast the compressor reacts. Depending on the ATTACK control position and the SPEED mode, the attack can be set from 0,5ms to 60ms.

RELEASE The RELEASE control (11-position gold contact switch) determines the time the compressor needs to get back to the initial value after a level reduction. Depending on the RELEASE control position and the SPEED mode, the attack can be set from 25ms to 6s.

INPUT This is a 11-position gold contact audio taper switch that determines the level of the signal entering the channel, as well as the threshold.

OUTPUT 21-position gold contact switch set for +10dB/-10dB of gain control. Once the desired amount of limiting or compression is achieved with the use of the INPUT control and the Z control, the OUTPUT control can be used to make up any gain lost due to gain reduction. This control is used to set the amount of compressed (WET) signal in the blender stage.

BLEND 11-position gold contact switch allows to mix compressed (WET) and uncompressed (DRY) signals using only one knob. A single move changes mixing ratio by 10%. This technique is known as parallel compression, or as New York compression. This technique usually needs external mixing console, but not when You use our powerful Preceptor.

SIDECHAIN HPF With this control (6-position gold contact switch) you can remove low frequency information feeding the compressing circuit from 40 Hz, 80 Hz, 120 Hz, 200 Hz, 320 Hz. It can be also turned off by setting OFF position.

LINK/DUAL MONO When set to the up (LINK) position, the two channels of the Preceptor act as a single stereo compressor, with equal gain reduction on both sides, even when there is transient activity only on one channel. You only need to set all the functions on the left and right channel in the same position. It is not a problem having only rotary and toggle switches installed in the unit. In the down (DUAL MONO) position, the Preceptor operates as two separate compressors, with the two channels operating completely independent of one another.


The GEM AUDIO LABS Preceptor is two-channel (stereo/dual mono), pure analog (Class-A, discrete) dynamic processor, in which the gain reduction is made by a transistor in the differential amplifier circuit with Zener diodes stabilization. In fact, there are two independent mono blocks sharing common enclosure, the ON/OFF switch and the LINK/DUAL MONO switch.
Power supply section

Special care has gone into the design of the power supply of the Preceptor because the power supply is the heart of any electronic system, and the better it is, the better the whole system works. In an audio system, this translates into a better sound quality, lower noise and unwanted distortion elimination.

Preceptor’s power supply is based on a 70VA toroidal transformer, which is made on our special order from properly selected cores. It is characterized by the highest quality, good supply of power, silent operation and excellent electrical parameters. It has a core and windings impregnation, electrical shielding (between windings) and magnetic (external screen), its center is flooded with resin. The transformer has an anti-vibration mount.

On the primary side of the transformer a special EMI filter is installed. It filters out any interferences that can enter the device from the electric network. Signal sections are separated from the power supply section by solid metal partitions.

Every channel has its own rectifiers and secondary voltage stabilizers. We have designed a special filtering stage with high capacity capacitors (10000µF) and special active filters (based on discrete elements) eliminating noise and ripple. The power of all stages is symmetrical and every section has independent stabilization, which keeps the voltage range of +/- 0.01 V. All the voltage stabilizers are mounted to the common heat sink which cools them evenly . Furthermore, the heat sink acts as an additional shield.
Rotary and toggle switches

The Preceptor has only rotary and toggle switches installed to obtain the best repeatability of the all settings. Thus You can easily return to your favorite settings. By using 1% low-noise metalized resistors and gold contact rotary switches, we succeeded to obtain (in the link mode) the difference between levels and characteristics of two channels in a range of +/- 0.1 dB.

Our aim is to support our customers only with the mastering-quality devices. Ain’t no games !

We say: “Mastering quality is for everyone!”
Signal patch and sidechain section

The Preceptor has installed a high performance, no compromise, professional input transformers made by Carnhill Transformers Ltd. All elements in the signal path and the sidechain section are built from the high quality discrete elements (low-noise transistors, ultra low-impedance electrolytic capacitors, precision film capacitors, precision silver-mica capacitors, 1% low noise metalized resistors, etc.) Only in the blend section transparent IC’s were used for uncompressed (DRY) and compressed (WET) signals mixing.

The gain reduction is made by a discrete VCA based on bipolar transistors and Zener diodes.
  • Massive sound
  • Hand made and calibrated
  • Pure analog design
  • 3U rack space
  • Internal PSU 115V/230V
  • Special power transformer
  • Two independent mono blocks
  • Ultra stable power supply
  • 16 matched Zener diodes in the signal path
  • Internal and external sidechain
  • Classic Carnhill transformers
  • Input Z switchable (2k5 or 10k)
  • Stereo or dual mono operation
  • Hard relay bypass
  • Sidechain HPF
  • Blend function (parallel compression)
  • Retro panel meters
  • Only gold contact stepped attenuators and toggle switches (no potentiometers!)
  • Easy-settings repeatability
  • Highest functionality!
  • Specifications
  • Inputs: Balanced XLR
  • Outputs: Balanced XLR
  • Ext. sidechain inputs: Balanced TRS
  • Signal transformers: Carnhill
  • Bypass: hard relay bypass
  • Input impedance: 2k5 or 10k switched on the front panel
  • Output impedance: < 50
  • 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: limiter, compressor
  • 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
  • Reviews
    Free shipping in Canada. Conditions
    Additional information
    For more information about the Preceptor-A, please visit the website of Gem Audio Labs
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