LA-76 Mojo Module Settings

The LA-76 Comp Mojo Module is a stereo optical compressor that can be used as a stereo processor and a dual mono processor. The device is set at the factory for dual mono processing, as that can be preferable from a stereo image standpoint.

There are multiple jumpers and trimmers on the board that allow you to customize how the module will affect your audio.  

General Operation Settings:

Trimmer L OUT, R OUT: Make-up Gain – This is calibrated at the factory to offset typical levels of gain reduction with the default threshold setting.  We recommend not touching this control unless you are using heavy amounts of gain reduction and need more output level. Turn clockwise to increase output and counterclockwise to decrease it. Increasing make-up gain will increase overall level, but will increase the signal to noise ratio.

Trimmer L THRESH, R THRESH: Threshold – Turn clockwise to lower the threshold for more compression and less saturation.  Turn counter-clockwise to raise the threshold for less compression and more saturation.  

Trimmer Ratio TRIM: Ratio Sensitivity – Turn clockwise to raise the sensitivity for each channel’s ratio.  Turn counter-clockwise to lower the sensitivity.  Please Note: each trimmer has a paint mark for factory settings, so it’s easy to get back to factory settings.

LINK Jumper : Insert this jumper to stereo link the left and right side-chain; you may want to adjust the ratio sensitivity trimpot on one channel to match compression levels more effectively. (More about this in Calibration section)

Left Ratio Jumper, Right Ratio Jumper: There are two sets of jumper pins to set the compression ratio on the LA-76. There are 4 total ratios available, 2:1, 4:1, 8:1 and 20:1 ratios are available. Set the jumper pin for the ratio of your choosing with the jumper pin on each channel. If no jumper pin is selected, 20:1 ratio will be active. *If you want to disable compression and only use the saturation of the mix amp circuitry, you will have to turn each threshold trimmer fully counterclockwise to bypass the compression circuitry.

Factory Calibration Procedure: 

For all these steps, send a 1kHz, 0 dbVU = +4 dBu (0.775VAC) sine wave signal to the Silver Bullet mk2 with the LA-76 installed.

OUT trimmer: Engage the Mojo C push button. Set Mojo C drive control to fully counterclockwise and Mojo C blend to full clockwise positions. Adjust the Out trimpots to achieve roughly 4db above unity gain on the level meter.

Threshold trimmer: With the Mojo C Drive Control at noon, set the threshold trimpot to read 3db above unity gain at noon on a level meter. With the drive control at max (full clockwise), you should be around 8db under unity gain, or roughly 12db of compression. Tweak these threshold trimpots so there is only a variance of .2db between the left and right channels, respectively.

Ratio sensitivity trimmer: Simply use these trimpots for further balancing of compression at max drive and noon. Then lastly, insert the link jumper and further balance ratio sensitivity trimpot(s) to find a healthy balance between compression balance in unlink and link mode. Remember, these factory settings should be notated by the markings on the trimpots so you can easily revert back  to factory spec. 

Enjoy, and congrats on owning the LA-76!