This is my Oakley Sound TB3031. It's a great sounding 303 clone with some nice extras like sub-oscillator, filter-FM, overdrive, etc. Unfortunately the PCBs have now run out and I'm not sure if Tony Allgood (of Oakley Sound) will be making any more - however you can purchase the schematics and PCB gerber plots from him to make your own PCB.
This 3031 has my own MIDI to CV converter based on the Fat Controller design and PCB. It has been customised specially for the 3031 and has the following features:
- MIDI In, MIDI Thru
- 3x gate outputs: Note on/off (0V/5V), Slide on/off (0V/5V), Accent on/off (0V/12V)
- Up to 15 high-precision CV outputs, of which 7 are currently used:
Note value 0V to +10.6V 3031 input is 1V/octave Velocity 0V to +10.6V Modulation wheel 0V to +10.6V Pitch bend -4.4V to +4.4V 3031 input is 2.2V/octave Software LFO -4.4V to +4.4V 3031 input is 10V/octave An extra pair of CV and Gate outputs (for controlling an external synth)
- Adding more CV outputs can be done by just adding more S&H caps and opamp output buffers to the PCB, and changing the software in the PIC.
- Comprehensive MIDI specification:
Note On (Pitch & Velocity) 0 = 0V, 120 = 10V, 127 = 10.58333V Note Off Modulation wheel MIDI CC 1 0 = 0V, 120 = 10V, 127 = 10.58333V Slide On/Off MIDI CC 65 0->63=Off, 64->127=On Accent On/Off MIDI CC 80 0->63=Off, 64->127=On All Sounds Off MIDI CC 120 All Notes Off MIDI CC 123 Pitch Bend 0x0000 = - full bend range
0x2000 = no bend
0x3FFF = + full bend range
Pitch Bend Range MIDI CC 16 0 = no bend
60 = 1 octave bend (+/-2.2V)
120+ = 2 octave bend (+/-4.4V)
LFO Speed MIDI CC 17 0 = slow (0.5 Hz), 127 = fast (65 Hz) LFO Extra Speed * MIDI CC 18 0 = slow (65 Hz), 127 = fast (146 Hz) LFO Waveform MIDI CC 19 0 = sine
1 = triangle
2 = falling saw
3 = rising saw
4 = square
LFO Depth MIDI CC 92 0 = 0V ptp, 127 = 8.8V ptp Legato Retrigger MIDI CC 82 0->63=Off, 64->127=On
- * LFO Extra Speed only has effect when LFO Speed is at maximum (127). LFO Extra Speed takes the LFO frequency further up into the audio range allowing different FM timbres. The frequency does not track note pitch so it has limited 'musical' applications, but is very nice for creating interesting timbres that will be played only on single notes (or at octave intervals).
The whole thing is housed in a 1U 19" rack mount case from Maplin Electronics (part no. N34AN, costs about £30) which has plenty of room for the MIDI to CV PCB (back left) and the mains transformer (back right). The front panel was made by Schaeffer AG.
- Front panel
- UK sources for parts
- MIDI to CV Schematic
- MIDI to CV Parts list
- MIDI to CV PCB layout
- MIDI to CV Source code