Mu-Tron Red Opto-Mod Module for Micro-Tron IV

Mu-Tron Micro-Tron IV "Red" Opto-Mod

Mu-Tron Opto-Mod technology was developed to accurately re-create the characteristics of the original photocells used in vintage Mu-Tron products. Throughout their research efforts, Mu-Tron discovered a few variations that were so pleasing and unique that they decided to make it a pluggable component.

The new Mu-Tron Opto-Mod, swappable technology allows you to change the overall ADSR (Attack, Decay, Sustain, Release) characteristics of your Micro-Tron IV. For many years, the performance of any given Mu-Tron III was based on the electrical performance of the photo-couplers which were used to give the devices their unique and expressive feel. Unfortunately, not all of these photo-couplers behaved the same and depending on what other components had drifted from their stated values, some units were magical and others were lackluster. The new Opto-Mod modules make it possible to precisely calibrate every unit to the same Mu-Tron standard of perfection.

Available Opto-Mod Models:

• The “Gold” Opto-Mod behaves like the vintage Hamamatsu 0805a photo-coupler found in the vintage Mu-Tron III pedals. It produces a very pleasing, general-purpose “curve” which works well in all settings. This is the stock Opto-Mod that comes in all Micro-Tron IV.

• The “Red” Opto-Mod, has a slightly slower attack and decay time, which offers a longer “curve.” It is a bit chewier and is great for slower, swampy types of music. Also, in the “Vintage Mu-Tron pre-amp jumper mode,” the Red Opto-Mod can get a little grittier. This unit models an older Mu-Tron III which has drifted out of factory calibration.

• The “Blue” Opto-Mod has a much steeper Attack and Release and is more suitable for fast, “Jaco” style bass playing. If you like to play 16th and 32nd notes and your filter just can’t keep up, this may be the one for you.

(Note: Each Opto-Mod is sold separately, this listing includes the Red Opto-Mod only)

Installation and Calibration Instructions:

- Remove 4 screws and bottom of enclosure
- Slowly remove current Opto-Mod by pulling with thumb and middle finger on wide edges
- Gently place replacement Opto-Mod on top of 8 pin socket
- Make sure all pins are aligned and then press firmly into place
- Set Micro-Tron IV face-plate control to Jerry G. or P-Bass setting in Micro-Tron IV manual
- While playing your instrument turn the right trimmer (red square in photo) to find "sweet spot"