Akashic Guitar effects circuit lookup
MIXTRACK

Enclosure not stated · 2 knobs

TH Custom Effects

U-Boat

Based on the Merlin Blencowe U-Boat

Category
Octave / Pitch
Controls
Mix · Track
Price
€9.16in stock
Buy the PCB at TH Custom Effects Build document1.5

From the vendor

A clean analogue suboctave generator based on Merlin Blencowe's U-Boat circuit. The dry guitar signal is squared and divided by a CD4013 flip-flop to generate a precise one-octave-down square wave, smoothed and blended with the original signal at the output. Merlin Blencowe is famous for his deep knowledge of valve circuits, but every now and then he releases stompbox designs of his own. The U-Boat is one of those designs — an analogue suboctave with a different approach to the well-known OC-2. With a few tweaks added on top, it tracks more reliably for a wider range of pickups. Merlin's project page documents the original circuit; valvewizard.co.uk is the home of all his work. This V1.5 boa

Schematic

The schematic is in the vendor's build document. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 54 rows

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RefValueNormalizedTypeNotes
Resistors 30
R110kΩ10kMetal film ¼ W
R210kΩ10kMetal film ¼ W
R610kΩ10kMetal film ¼ W
R710kΩ10kMetal film ¼ W
R810kΩ10kMetal film ¼ W
R1010kΩ10kMetal film ¼ W
R1110kΩ10kMetal film ¼ W
R1210kΩ10kMetal film ¼ W
R1310kΩ10kMetal film ¼ W
R1510kΩ10kMetal film ¼ W
R1610kΩ10kMetal film ¼ W
R1810kΩ10kMetal film ¼ W
R1910kΩ10kMetal film ¼ W
R2010kΩ10kMetal film ¼ W
R3100 Ω100Metal film ¼ W
R26100 Ω100Metal film ¼ W
R410MΩ10MR17 — only fit if IC2 is not a LM833.
R1710MΩ10MR17 — only fit if IC2 is not a LM833.
R2710MΩ10MR17 — only fit if IC2 is not a LM833.
R51MΩ1MInput bias for IC1A
R92.2kΩ2.2kIC1B gain network
R214.7kΩ4.7kQ1 source resistor
R2347kΩ47kIC4A summing network
R2447kΩ47kIC4A summing network
R2547kΩ47kIC4A summing network
R14100kΩ100kEnvelope / output stage
R28100kΩ100kEnvelope / output stage
R29100kΩ100kEnvelope / output stage
R3082kΩ82kTRACK pot end-stops
R3182kΩ82kTRACK pot end-stops
Capacitors 15
C1100 µF100uPolarised electrolytic — supply reservoir
C222 µF22uPolarised electrolytic — VR decoupling
C3100 nF100nBox film — supply / input coupling
C4100 nF100nBox film — supply / input coupling
C522 nF22nBox film
C1122 nF22nBox film
C64.7 nF4.7nBox film — IC1B Sallen-Key & IC1C feedback
C74.7 nF4.7nBox film — IC1B Sallen-Key & IC1C feedback
C8680 nF680nBox film — envelope hold cap
C910 pF10pCeramic — IC2B compensation
C1010 µF10uPolarised electrolytic
C1310 µF10uPolarised electrolytic
C1410 µF10uPolarised electrolytic
C122.2 nF2.2nBox film — IC4A feedback HF rolloff
C15100 pF100pCeramic — IC4B HF rolloff
Diodes 1
D11N40011N4001Reverse polarity protection on +9 V supply.
Transistors 1
Q1J112J112N-channel JFET switch — gates the suboctave signal. 2N5485
ICs 4
IC1TL074TL074Quad JFET-input op-amp, DIP-14.
IC2LM833LM833Dual low-noise op-amp, DIP-8 — highly recommended . TL072 works but R17 must then be fitted.
IC3CD4013CD4013Dual D-type flip-flop, DIP-14 — divides square wave by 2.
IC4TL072TL072Dual JFET-input op-amp, DIP-8. NE5532 OPA2134
Potentiometers 2
MIXB10kB10k16 mm board-mount, B-taper (linear).
TRACKB10kB10k16 mm board-mount, B-taper (linear).
Switches 1
SW12PDT2PDTTrue-bypass footswitch (PCB-mounted or wired).