MOTM-820 VC Lag Processor

MOTM-820 VC Lag Processor

Courtesy of Paul Schreiber, here is the link to the Synthesis Technology User Guide: http://synthtech.com/motm/docs/MOTM820%20User's%20Guide.pdf

The MOTM-820 is used to add slew to an input. The most common use would be to add portamento to a control voltage feeding a VCO .  In analog keyboards with portamento (Moog called this glide) the rise and fall times were the same. This is because a simple RC filter is controlled by a single pot. The shape is the same: an exponential rise and fall. Although we are used to hearing this shape, the fact that we have an exponential voltage feeding an exponential response (1V/Oct of the VCO) means that musically we are limited.

The MOTM-820 is your solution! It is the most advanced lag processor ever designed. How can we claim this? Well, just check out the features:

• Independent voltage control of both rise (UP) and fall (DOWN) times
• Times variable from 500us to 5 minutes
• Ganged UP/DOWN control to emulate standard portamento effects
• A new SHAPE control that varies the glide slopes from Linear to Log
• Remote or panel BYPASS to turn the effect off without any DC shift!

Easy to build, the MOTM-820 also offers a "hidden multiple": it can drive 3 VCOs (or other modules) from a single input! The output stage is a special "capacitive cable driver" for driving long cables (up to 20 feet) without any voltage drop