Ottawa

Ottawa is a voltage-controlled envelope filter, reminiscent of classic “auto wah” pedals like the Mu-Tron III. Ottawa has two stages, a filtering stage with CV over the cutoff frequency, and a VCA stage for the envelope. VCA stage accepts triggers or gates and has additional CV input to control the depth of the VCA.

Schematic

As with any schematic found on the internet, exercise caution when building. Test the build before plugging it into your case. If you find mistakes in the schematic, or you have recommendations for improving the design, feel free to contact us and let us know.

BOM

• Capacitors
  • 680pf (1) C6
  • 1nf (1) C4
  • 4.7nf (2) C5, C7
  • 100nf (4) C1, C2, C3, C8
• Resistors
  • 1k (7) R2, R14, R15, R18, R22, R23, R24
  • 2.2k (1) R5
  • 4.7k (1) R17
  • 10k (7) R4, R16, R20, R21, R25, R27, R29
  • 20k (1) R7
  • 47k (3) R6, R19, R26
  • 50k (2) R10, R11
  • 100k (2) R8, R9
  • 680k (1) R28
  • 1M (1) R1
  • 2.2M (2) R3, R13
  • 5M (1) R12
• Transistors
  • MPSA42 (1) Q1
• Potentiometers
  • 5k (1) RV3
  • 20k (1) RV4
  • 100k (2) RV1, RV2
• ICs
  • TL071 (1) U5
  • TL072 (1) U3
  • TL074 (1) U2
• 1N4148 diodes (2) D1, D4
• LEDs (2) D2, D5
• Zener diode (1) D3
• Vactrols (2) U1, U4
• Audio jacks (6) J1, J2, J3, J4, J5, J6

Demos