MOTM-700 Dual 2:1 Voltage-Controlled Router

MOTM-700 panelQuantity: 1
Modifications: none

From the Synthtech website:

The MOTM-700 is a dual, bi-directional SPDT switch that is “toggled” when an input control voltage exceeds a trip-point set by a panel knob. Special circuitry handles routing of audio (cross-fading VCAs) or control voltage (fast, low-offset switches). The MOTM-700 has two identical, totally independent sections.

Think of a SPDT (single-pole, double-throw) mechanical switch. When the switch is ‘up’, signal A is is routed to X. If the switch is ‘down’, then signal B is routed to X. There are two ways of viewing this: two inputs are routed to one output, or one input is routed to two outputs; it’s truly bi-directional. This is exactly how the MOTM-700 works. What makes it useful is that you control the selection with a control voltage! The MOTM-700 uses a circuit that compares the input control voltage with another voltage, set by the panel pot SWITCH. The SWITCH control is adjustable from -5V to +5V.

  • If the CV IN voltage is less than the SWITCH setting, then A and X are connected.
  • If the CV IN voltage is greater than the SWITCH setting, then B and X are connected.

A MODE switch selects if audio or control voltages are being routed. In the AUDIO mode, a special circuit switches by a very fast cross-fading between channels. This eliminates pops and clicks. If the MODE is voltage, then a high-speed, low resistance CMOS switch is used that is good enough for switching VCO control voltages without adding drift or offsets! It can also switch at audio rates as well! This can result in some very bizarre timbres.

The MOTM-700 patches below were contributed by John Loffink
The Microtonal Synthesis Web Site

Full wave rectifier

Signal source
MOTM-700 Dual VC Router
Oakley Multimix (need gain of -1), or
Mixer Comparator (using the inverting output)
Signal source to MOTM-700 CV IN (A/B/X) and to MOTM-700 IO B and
Signal source to Multimix IN1(or Mix-Comp MIX 1)
Multimix OUT1 (or Mix-Comp INV OUT) to MOTM-700 IO A
MOTM-700 IO X is full wave rectified waveform
Multimix IN 1 knob at -5 (or Mix-Comp INV switch up)
MOTM-700 switch knob at 0
MOTM-700 mode switch to voltage

Pulse Divide by Two

This divides a square wave frequency by two. Good for clocking/gate applications or suboctave square waveforms.

MOTM-320 VCLFO or MOTM-390 uLFO or MOTM-300 VCO
MOTM-700 VC Router
Oakley Multimix (need gain of -1), or
Mixer Comparator (using the inverting output)
300/320/390 TRIANGLE to MOTM-700 CV IN (A/B/X)
300/320/390 SQUARE/PULSE (set pulse at 50%) to Multimix IN1 (or Mix-Comp MIX 1) and to MOTM-700 IO A (This needs to be the same oscillator as the triangle wave.)
Multimix OUT1 (or Mix-Comp INV OUT) to MOTM-700 IO B
MOTM-700 IO X is divided square out

MOTM-300/320/390 Rate/Frequency = any
MOTM-700 Mode = voltage
MOTM-700 Switch = 0 for square wave, any other setting for uneven pulses
Multimix IN 1 knob at -5 (or Mix-Comp INV switch up)
For modulation of pulse width, mix the TRIANGLE wave with a second LFO sine or triangle, then feed that to the MOTM-700 CV IN.

Syncopated Clock with Random Probability

This gives a nice syncopated, semi-random clock, but always on the beat. Good for triggering envelope generators.

MOTM-100 or MOTM-101 Noise/S&H
MOTM-700 VC Router
MOTM-830 Dual Mode Mixer, or
Mixer Comparator (using the bias control)
MOTM-320 PULSE or MOTM-390 SQR to MOTM-100/101 EXT CLK and to MOTM-830 IN 3 (or Mix-Comp MIX 1) and to MOTM-700 IO A
MOTM-100/101 S&H OUT to MOTM-830 IN 2 (or Mix-Comp MIX 2)
MOTM-830 OUT1 (or Mix-Comp MIX OUT) to MOTM-700 CV IN (A/B/X)
MOTM-700 IO X is syncopated clock

MOTM-100 LEVEL = 10, SLEW = 0
MOTM-320 or MOTM-390 RATE = about 8
MOTM-700 SWITCH = +0.5 to +3.5
MOTM-830 (or Mix-Comp) IN 2, IN 3, BIAS (optional) = set to taste

Semi-random patch

Any 2 LFOs
MOTM-700 Dual VC Router
MOTM-820 VC Lag

Any LFO 1 waveform to MOTM-700 IO A
Any LFO 2 waveform to MOTM-700 IO B
MOTM-700 IO X to MOTM- 820 IN
MOTM-820 OUT1 to MOTM-700 CV (A/B/X)
MOTM-820 OUT2 to any control voltage input, VCO pitch, VCF cutoff, etc.

LFO rate, Router switch, and Lag Up, Down and Up/Down will cause significant change to the semi-random pattern. Adjusting the Lag control too far to the right may cause the Router to stay pegged to one side. The patch creates a feedback path so that lagged versions of LFO 1 and LFO 2 alternate control of the router switching.


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