1 Slot

Available as an assembled Module and as a DIY project.

This Module is currently available.

Compressor One

Outstanding VCA compressor with multi-channel operation capability and user configurable sidechain filters.



Threshold : -30dBu to +20dBu

Attack : 100uS to 75ms (Also active in A1 or A2 Recovery mode).

Recovery : 75mS to 3S or A1: 50ms/5S or A2: 100mS/2S

Ratio : 0 to Limit (>10:1)

Gain makeup : -6dB to +18dB

Dry/Wet : Fully Dry (Uncompressed) through to fully Wet (Compressed).

Sidechain Filter switch : OUT or low pass filters F1 or F2. These can be user defined by jumpers.

Optional Sidechain and Dry path insert points.

Hard/Soft switch.

Feed forward/Feedback switch.

“L” switch providing “Sidechain Listen” facility or multichannel linking.

“Master “LED illuminated when a module is the “Master” of a group of modules.

Audio meter range : Signal present to +18dBu

Gain Reduction meter range : 1.5dB to 22dB


+/- 0.5dB 20Hz to 20 kHz with no compression.


Measured true RMS, 20Hz to 20 kHz

Compressor OUT: -98dBu

Compressor IN (unity gain) -88dBu (with THAT4301 VCA).

With the BYPASS card option there is no noise contribution when the compressor is switched OUT.


Better than 0.05% at 1 kHz and +10dBu input with compressor OUT.

With the compressor IN the THD&N is similar with moderate degrees of compression but will increase depending on control settings and signal frequency.


Supply rails +/-16V

Maximum input level: +27dBu

Maximum output level (Compressor OUT): +27dBu into 200k load, +25dBu into 600ohm load.

Internal operating level -6dB. This is also the level at unbalanced insert points.


Input impedance (balanced): 24k ohms.

Output impedance (balanced): 75 ohms.

Unbalanced SIDECHAIN insert input impedance: 50k ohms.

Unbalanced SIDECHAIN insert output impedance: less than 75 ohms.

Unbalanced optional DRY insert input impedance: 50k ohms.

Unbalanced optional DRY insert output impedance: less than 75 ohms.


Compressor OUT better than 7V/uS.

Compressor IN 2V/uS


submitted Mar 17th 2020, 14:11 by fragletrollet | last Change Jul 28th 2021, 12:52 by tipa