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mutu

David Huss's avatar
David Huss authored
Changes to the circuit:

- Replaced R8, R20 with 100R (was 220R) to increase vactrol/led current
- Reversed turning direction of pots LVL-A and LVL-B to the expected
direction
- Simplified Sync-Section (removing an resistor and a mosfet)
717680ac
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README.md
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MUTU – MUTUAL VCO

A synthesizer with two oscillators in a mutual relationship with each other.

Goals

  • flexible sound-generator
  • simple and DIY-friendly
  • eurorack-compatible (CV inputs for FM and VCA, size fits eurorack)

Non-Goals

  • No perfect tonal tracking intended
  • No features that raise the parts count too much

Topology

Interface

Panel draft with 16 HP (~80 mm wide, 119 mm tall)

Inputs

Name Function Normalization
CV-VCA-A CV-Input for the first VCA. Positive voltages turn up the level of the first oscillator Fixed positive voltage
CV-VCA-B CV-Input for the second VCA. Positive voltages turn up the level of the second oscillator Fixed positive voltage
CV-FM-A Frequency modulation (FM) input for the first oscillator -
CV-FM-B Frequency modulation (FM) input for the second oscillator Signal plugged to the first FM-Input (CV-FM-A)

Knobs

Name Function
FREQ-A Sets the base frequency (pitch) of the first oscillator
FREQ-B Sets the base frequency (pitch) of the first oscillator. If Track is on, this gets added to the frequency set by FREQ-A
MOD-A Changes the amount of frequency modulation (FM) the second oscillator applies to the first
MOD-B Changes the amount of frequency modulation (FM) the first oscillator applies to the second
ATT-FM-A Attenuates any incoming (external) modulation signal plugged into the input CV-FM-A
ATT-FM-B Attenuates any incoming (external) modulation signal plugged into the input CV-FM-B. If no signal is plugged into CV-FM-B the signal of CV-FM-A is used here.
SHAPE-A Morphs the waveform of the first oscillator between triangle and sawtooth. Might also detune the oscillator
SHAPE-B Morphs the waveform of the second oscillator between triangle and sawtooth. Might also detune the oscillator
LVL-A Sets the level of the first oscillator. If something is plugged into the CV-input CV-LVL-A this knob attenuates the level of the incoming CV-signal.
LVL-B Sets the level of the second oscillator. If something is plugged into the CV-input CV-LVL-B this knob attenuates the level of the incoming signal.

Switches/Toggles

Name Function
S_TRACK Switches on or off the tracking function where the second oscillator follows the frequency changes of the first.
S_SYNC Hardsyncs the second oscillator to the first one

Outputs

Name Function
OUTPUT Outputs the summed signal of both oscillators