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Distortion pedal for the guitar and the bass


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Distopia is a DIY distortion pedal, mainly for guitar and bass. This page contains the building instructions.

This pedal was designed in collaboration with the SheWolf music band, for their use.

The circuit is loosely based on the Boss DS-1 circuit but has moved quite far away from it during design. However, the idea remains broadly the same.

Above, the first model, a fully working prototype.

And above, an early test version of the circuit, on breadboard.


Bill of materials

NameQtyValueSpecific contraints
or model
C1, C3, C5, C13 4100nF Film, pitch 5mm, 7.2×4.5mm²
C2, C8, C14, C24 41µF Film, pitch 5mm, 7.2×4.5mm²
C4 1100pF Ceramic, pitch 2.5mm
C6, C23 2100µF Electrolytic, 25 V, pitch 2.5mm, Ø6.3mm, low ESR
C7 1250pF Ceramic, pitch 2.5mm
C9 1470nF Film, pitch 5mm, 7.2 × 4.5mm²
C10 110nF Film, pitch 5mm, 7.2 × 7.2mm²
C11, C29 215nF Film, pitch 5mm, 7.2 × 7.2mm², accurate value if possible (≤5%)
C12, C28 268nF Film, pitch 5mm, 7.2 × 7.2mm², accurate value if possible (≤5%)
C15 147µF Electrolytic, 25V, pitch 2.5mm, Ø 6.3mm, low ESR
C16, C19, C25, C26, C27 5100nF Ceramic, pitch 2.5mm, doit loger dans 2.5×5mm², hauteur 4mm max.
C17 122nF Ceramic, pitch 2.5mm
C18, C20, C21 347nF Ceramic, pitch 2.5mm
C32 12.2nF Film, pitch 5mm, 7.2×4.5mm²
D1 1LED 5 mm, red, low current (1–2mA)
D2, D4, D6, D7, D8 5Small signal silicone diode 1N4148
D3 1LED 3mm, red, standard (20–40mA)
D5, D9, D10, D11 4Germanium diode 20V, 1N34A
D12 1Zener diode 18V, 1N4746A
J1 12.1mm male power jack socket Panel mount, insulated from the enclosure
J2 1Socket for 9V battery
J3 1Momentary SPST footswitch Soft touch
J4 16,35mm stereo female jack socketPanel mount, Neutrik NYS230
J5 16,35mm mono female jack socket Panel mount, Neutrik NYS229
J6 1Toggle switch SPST Panel mount
Q1 1JFET-N TO-92, pinout: DSG, J201
Q2, Q10 2NPN TO-92, pinout: EBC, 2N5088
Q6, Q7, Q8 3JFET-N TO-92, pinout: DSG, 2N5457
Q9 1MOSFET-P TO-251-3 or TO-220-3, pinout: GDS, low Rds, Vds −30V, NTD2955-1G, IRFU5505PBF or IPP80P04P4L-08
R1, R11, R22, R44 41kΩ
R2 12.2MΩ
R3, R34 23.3kΩ
R4, R10, R20, R23, R26, R39 6100kΩ
R5, R19, R27, R32, R33, R36, R4071MΩ
R6 1150kΩ
R7, R21, R28 3330kΩ
R8, R18, R25, R35, R41, R42 610kΩ
R12, R38 210Ω
R13 1820Ω
R9, R14, R15 32.2kΩ
R16, R17 26.8kΩ
R24 18.2kΩ
R43 1120kΩ
R45 1330Ω
R46 1100Ω
R50 182kΩ
RV1 110kΩ potentiometer Linear, Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
RV2 1250kΩ potentiometer Inverted logarithmic (C type), Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
RV3 110kΩ potentiometer Inverted logarithmic (C type), Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
RV4 150kΩ potentiometer Linear, Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
RV5 1100kΩ potentiometer Logarithmic, Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
RV6 1500kΩ potentiometer Linear, Ø 16mm, vertical on PCB, 16mm min pin length. Alpha 16mm type 4
U1, U2, U4 3Operational amplifier Dual, low noise, DIP-8, NE5532AP. U4 has less requirement on noise and can be just a NE5532P.
U3 1Hex schmitt trigger DIP-14, CD40106BE
U1, U2, U4 3IC socket, DIP-8 Hollow body in order to put a 100nF capacitor inside
U3 1IC socket, DIP-14 Hollow body in order to put a 100nF capacitor inside as well as two resistors
Wire About 1m Insulated. At least 0,25mm² (AWG 23), preferably stranded.
Enclosure 11590BB ou équiv. Eddystone 29830PSLA
Knobs for the potentiometers 6 Ø 6mm shaft, with screw
PCB 1 See below

Important notes:

Count about 50€ of good quality components.

Tools: soldering material, cross-head screwdriver, cutting pliers, drill, drill bits from 3 to 12mm for the metal, round file for the metal, a set of wrenches or adjustable wrench, tools to strip wires, insulated tape, metal saw.

Schematics and PCB

Electronic schematics, Gerber files for the print, layouts and KiCAD source files are located in the following archive: distopia-2018-09-03.zip (2776kB).

I can provide PCBs at cost price + shipping fees. Please contact me if you are interested.

Building instructions


The pedal is put together pretty tight in a 1590BB enclosure. There is no room for a battery, power supply must be external. However the circuit has been designed for battery so it could fit in a slightly bigger enclosure. The board is attached with the potentiometers but there are mounting holes if you need it to be mounted differently on the enclosure. The jack sockets must be located at the bottom of the enclosure. The power jack and the Dry/mix switch are located at the top, between two potentiometers, and as close as possible to the base so their pins will not make contact with the board. Holes must be placed as accurately as possible.

Panel artwork is available here (29MB). To be printed on self-adhesive transparent paper. Clean and wipe the enclosure, stick the artwork then add several layers of varnish to protect it.


Solder the components sorted by height. The order is given by layout.ods (order for film capacitors may vary depending on the parts). This file indicates the position of each component on the board, too.

This point require some care: R26 and R27 are intended to fit in the socket of the CD40106. Because the socket thickness may vary, make sure that everything fits well before soldering. If not, it is possible to file down the inner edges of the socket. Or to solder the resistors once the socket is set up.

One more thing: be careful when bending the legs of the 1N34A diodes. Indeed, the legs are to be bent right at the end of the glass enclosure. However the package is very fragile and could break if the legs apply too much pressure on it. In doubt, solder these diodes vertically.

The D3 LED (on the component side) has no visual use, so it can be soldered at any height.

Carefully cut the legs of components that will overlap with the potentiometers. Cut the wires to the right length and solder them to the PCB, connectors and switches. Don’t connect the audio output ground wire, it could make a ground loop with the conductive enclosure.

ConnectionNumber of wiresLength
Audio input36cm
Audio output1 or 27cm
Power jack35cm
Dry/mix switch212cm


With cutting pliers, cut the anti-rotation bits from the potentiometers and the rotative switch. Fasten them to the enclosure, without tighten so they can move easily. Be careful not to mix up the different kinds of potentiometers. Ajust the potentiometers by fitting the PCB on them, but without soldering at the moment. When the PCB is fitted, fasten the potentiometer nuts.

Now remove the PCB and cut two strips of insulating material to be inserted between the potentiometers and the PCB, in order to avoid any short. I used offcuts of transparent sheets, but any other material would be fine.

Put the LED and fit the PCB again on the potentiometers. Solder them, as well as the LED. Avoid the LED to stick out too much, to protect it from impacts. Fasten the other connectors and switches. The Dry/mix switch should have its wires on the Dry side.

When everything is ready, screw the knobs on the pot shafts. To avoid fastening them too low (which can cause friction and blocking), you can insert small elements between the top of the shaft and the bottom of the knob. For example, I used a sheath from a thick electric cable, cut into 5mm pieces.


The user manual is available here (PDF, 267 kB).


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