Q2 Audio

The ADR Compex F760-RS by Q2 Audio reintroduces, at long last, the venerable and highly sought-after dynamics processor of yesteryear. The unique character and spirit of the Compex can be heard on many classic recordings (think of that huge, commanding drum sound on When the Levee Breaks by Led Zeppelin, for instance). With painstaking attention to detail, Q2 Audio has masterfully reproduced the exact circuit design of the original Compex, with a handful of new features and updated components.



Re-issue of the classic stereo compressor/limiter/expander/gate


Functionally, the new Compex has all the same features and settings as the original unit, employing the same super-flexible FET-based compression, limiting and gating. Switchable threshold, compression ratio, and attack/release times are available with all the same settings and a stereo link switch is provided for linking the two channels together for operation in stereo. An all-new external side-chain insert has been added to the new Compex, letting you feed the detector circuit of the compressor with an independent sound source. The side-chain insert can be set to control the gate circuit, instead, by simply switching over an internal jumper. The limit section has a switchable 50us "pre-emphasis" setting in addition to the normal “on” position. Pre-emphasis was originally used for limiting high frequencies to prevent over-modulation during broadcast use. Pre-emphasis boosts the high frequencies entering the limiter side-chain, acting as a de-esser causing limiting action on sibilant high frequencies. The compressor side-chain insert is useful for adding an EQ to the side-chain audio signal to create "vocal stresser" type frequency-dependent compression effects or inserting another audio source for “ducking".

Improving upon some of the components and build-quality concerns of the original Compex, a high-quality meter has been employed (replacing the discontinued Sifam™ Director 14 meter) and the original “ABC” cards have been combined to a single PCB to allow for more efficient manufacturing. Also, some slight alterations have been made to the calibration functions to help the unit maintain calibration over a longer period of time. The original potentiometers were an open frame design which became noisy as time wore on, the re-issue has sealed conductive plastic potentiometers to improve the usable life-span.

With a wide range of features and functions, the new ADR Compex by Q2 Audio can meet the needs of any dynamic-processing task, adding a character and flavor all its own. Those familiar with the original Compex will be pleased to see how faithfully recreated this reincarnate really is, with a few enhancements and updates to make one of the best compressor/limiters just that much better.


F765 Compressor/Limiter Module

q2 compex f765 500

Manufactured by Q2 Audio in close collaboration with Audio & Design, the F765 is a remake of the classic F760-N module and has now been adapted to the 500 series modular rack system. It is authentic in every detail and reproduces the exact sonic qualities of the original product.

Using the original discrete analogue circuit design employing a feedback FET technique and maintaining the use of the same components that give this product such a distinctive sound, the new F765 compressor/limiter will add dynamic punch to your sound as well as controlling peak excursions.

The original F760-N module was used by major recording artists worldwide throughout the 60s, 70s, and 80s. This famous, iconic processor was instrumental in shaping the sounds of that era. Now as the F765 it returns to take a worthy place in the ever-popular 500 series rack system with it's unique signature on the sounds of today.


  • Single channel level control offering simultaneous compression gain reduction with peak limiting
  • Precision calibrated compressor/limiter threshold control which allows the user to “dial up” the amount of compression required before peak limiting occurs
  • Switched Compression values from 1:1 (amplifier), 2:1, 3:1, 5:1, 10:1 & 20:1 (limiter)
  • Auto dual platform release function – allows fast transient recovery on a “build-up” slow release


  • Gold contact rotary switches
  • Gold contact toggle switches
  • Conductive plastic potentiometers
  • PCB headers for possible future connection to E900 type EQ
  • Sidechain Insert and Bus output functionality per Radial Engineering specs
  • Sidechain insert is jumpered by default
  • Sidechain insert send minimum external load of 10K

Input: 10K ohms Unbalanced

Output:  Transformer Balanced (Cinemag CMOB-3L) Max output: 20dBu, 18.5dBm

Metering:  Sifam Fast Responding analog meter

Stereo Linking:  Must ordered as stereo pair for proper stereo performance

Power requirements:  +/-16V DC @ 70mA per rail (brief 400mA turn-on surge)

System Gain:  34dB with input/output attenuators fully open. Unity gain in Bypass mode

Peak Limiter: +14dBu maximum with unattenuated output. Referred to unattenuated input level 20dBu
Compressor:  Calibrated with reference to Peak Limiter thresholds and marked 0 – 20dB in 2dB steps. (Reference to unattenuated input level this is -20dBu to -40dBu)

Peak Limiter: 250mS,
Compressor: 25mS, 50mS, 100mS, 200mS, 400mS, 800mS, 1.6 secs, 3.2 secs + Auto release function

Peak Limiter: < 250uS for 100% control of overshoot – without any over limiting. (measured at 1KHz for 10dB gain reduction)
Compressor: 250uS, 2.5mS, 25mS

Distortion:  Measured at 1KHz for 10dB compression & 3.2 secs release time.
Compressor: at +10dBu threshold <0.1% (typically 0.04%)
Peak Limiter: at +14dBu threshold <0.3%

Frequency Response:
Balanced: < -0.5dB at 20Hz & < -0.75dB at 20KHz

Signal – Noise Ratio:
Referred to Peak Limiter threshold level as set by output attenuator: better than -80dB (Measured with low pass filter -3dB at 25HKz)

Stereo Matching:
Control volts matching on compressor to within ±1dB of each other, consequently no image shift during operation
Selectable Peak Limiter operation
Peak Limiter on – off or Pre-emph (50uS time constant)

Overall Gain Reduction Meter scaled 0 – 20dB in 4dB divisions. White scale on black background with yellow pointer
Peak Limiter operating: Red indicator