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the characteristic ‘dow’ sound. Oddly, the envelope amount also gets higher for repeated
triggering of the gate.
GATE LED: Lights green when an active gate is present.
VCF DECAY: Controls the time it takes for the envelope to decay down to zero. From ‘dit’
sounds to ‘dowww’ sounds.
ACCENT DECAY: This will allow the filter decay time to be a certain proportion of the time
set by the VCF DECAY pot when accent has been triggered. In other words you can set the
accent decay time from very short to the same as the VCF DECAY time.
FILTER MODULATION: Adjusts how much of the selected VCO output modulates the
VCF’s cut-off frequency. This brightens up dull timbres and somehow gives them a burbling
sound. Use with high values of resonance for really odd noises. Remember that the source of
the modulation comes from the VCO WAVE switch. So changing the waveform makes a huge
difference to the sound.
VELOCITY CONTROL: This switch turns the velocity processor on or off. With it off,
velocity has no control over the slides and accent modes of the 3031. When on, the velocity
processor measures the value of the velocity CV and controls the synth accordingly.
Example velocity CV processor sensitivity:
Velocity CV Approx MIDI value Slide Accent
0-2V 0 -31 no no
2-4V 32-63 no accent
4-6V 64-95 slide no
6-10V 96-127 slide accent
Adjust the SENS trimmer for actual processor sensitivity.
Although it is called velocity control, you could of course use any external CV. One example I
have seen uses the second channel of an analogue sequencer to control the 3031’s processor.
With an internal tbDAC, the user is not aware of any CV control. You just simply bang away
at your sequencer, or keyboard, and the velocity value of each MIDI note determines what
mode the 3031 drops into.
ACCENT: When accent is triggered the VCA can become louder and more punchier. This
pot controls how much the accent has an effect. Like the TB303, the 3031 also modulates the
VCF with this signal.
VCA DECAY: The VCAs envelope can be changed from about 0.1s to about 3s with this
control. In other words it affects how long the note is heard after initial triggering.
OVERDRIVE: Adjusts how much the output waveform of the filter gets distorted. Fully
anti-clockwise gives an undistorted TB sound, while clockwise gives a heavily clipped
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