YuSynth Wavefolder PCB

YuSynth Wavefolder Module Bare PCB

(£17.29 exc. tax)
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YuSynth Wavefolder


A bare double sided PCB 100x75mm (no need for the wire jumper links shown on the PCB layout) for the Yusynth Wavefolder synth module. These PCBs are manufactured by Soundtronics with a percentage of the sale going to the creator of the YuSynth - Yves Usson. These are early days for the YuSynth Modular Synth at Soundtronics, our plan is to stock PCBs for all of the projects as well as components, kits and front panels. This is going to take time but will eventually be as comprehensive as our MFOS range.

No components are included with the PCB but check out our Synth Components section where you should find what you need. We do suggest visiting the YuSynth Wavefolder project page for detailed information on this PCB.

This circuit is a device which provides wonderful sonic possibilities. This module performs a non-linear transformation of a simple waveshape (triangle or sawtooth) into a complex waveform rich in overtones.

This module is based on Jürgen Haible's wavefolder B that Yves associated to a VCA at the input to dynamically control wavefolding, and with an amplifier to adjust the output level.

This circuit is made of three parts : the first one is based on U2, Q1 and Q3 and is a voltage controlled amplifier (VCA) and accepts an input signal ranging from -10V et +10V with a control voltage (CV1) ranging from 0 to 15V.  The second part made of U1b, U1c and U1d and diodes D1 à D20 is actually Jürgen Haible's wavefolder. Next, the third part is a level amplifier which gain is set to obtain an output signal in the range -10V to 10V. By the way, if you need to modify the voltage range of the input and output signals, it is just a matter of changing the values of R20 & R21 for the input signal and that of R17 & R18 to adjust the output level.

Parts List

The parts list below is direct from the YuSynth website. The value in the parts list is the default value and may differ to that quoted in the schematic / PCB silk image.

The parts list excludes knobs although we have standardised on the Cliff KM20B but it does include 1/4" jack sockets. All parts are available individually (use the part number in the search box above) or as a components kit that excludes sockets and knobs.

Reference Part No. Description Qty
R21* Depends on input level 7163-039 330R 0.25W 1% Metal Film Resistor 1
R19 7163-043 470R 0.25W 1% Metal Film Resistor 1
R21* Depends on input level 7163-047 680R 0.25W 1% Metal Film Resistor 1
R3 7163-061 2k7 0.25W 1% Metal Film Resistor 1
R14,R15 7163-069 5k6 0.25W 1% Metal Film Resistor 2
R17 7163-071 6k8 0.25W 1% Metal Film Resistor 1
R22,R23 7163-075 10k 0.25W 1% Metal Film Resistor 2
R5, R6, R7, R8, R9, R10, R11, R12, R26,R27, R29 7163-079 15k 0.25W 1% Metal Film Resistor 12
R33,R34 7163-083 22k 0.25W 1% Metal Film Resistor 2
R13 7163-085 27k 0.25W 1% Metal Film Resistor 1
R4,R28 7163-087 33k 0.25W 1% Metal Film Resistor 2
R16,R18 7163-093 56k 0.25W 1% Metal Film Resistor 2
R30 7163-095 68k 0.25W 1% Metal Film Resistor 1
R1, R2, R20, R24, R25, R31, R32 7163-099 100k 0.25W 1% Metal Film Resistor 8
JK1, JK2, JK3 7212-203 Pack of 3, Switchcraft 1/4" Jack Sockets 1
U2 7212-331 Turned Pin 0.3 inch Dil IC Socket 8 Pin 1
U1 7212-332 Turned Pin 0.3 inch Dil IC Socket 14 Pin 1
Q3 7212-401 BC547C Diotec Bipolar NPN Transistor TO-92 1
D1 to D20 7212-481 1N4148 3mV Matched Pairs 10
Q1, Q2 7212-492 BC547C Hfe Matched Pair 1
U2 7212-542 Dual Op-Amp BiFET TL072CP 1
U1 7212-544 Quad Op-Amp BiFET TL074 1
C2,C3 7212-749 100nF 5mm X7R Dielectric Radial Ceramic Capacitor 2
A1 7212-854 Multiturn Cermet Preset Top Adjust SIL 1k 1
A2 7212-859 Multiturn Cermet Preset Top Adjust SIL 50k 1
C4,C5 7213-113 Radial Electrolytic Capacitor 22uF 35V 2
P2 7300-250 Synth Pot 16mm 50k Lin 1
P1,P3 7300-255 Synth Pot 16mm 100k Lin 2

Setting and Trimming

Trimming is quite easy if you use matched NPNs for Q1 and Q2, and 1% tolerance resistors for R22 to R27. You will need a dual trace scope, a DVM and a sinewave generator. Using 10 turn trimmers is a little bit more expensive than using 1 turn but makes it easier to adjust with high accuracy.
  1. Set A1& A2 to mid-range.
  2. Connect the sinewave generator (freq. 1KHz, 10Vpp) to input 1, P1 turned fully clockwise (maximum signal).
  3. Connect the sinewave generator to the first input of your scope.
  4. Connect CV1 to 0V and turn P3 fully clockwise (maximum gain).
  5. Connect the output of the VCA (pin 1 of U2a) to the second input of the scope.
  6. Adjust the trimmer A1 in order to have a perfectly symmetrical sine wave at the output (the best way is to superimpose the trace of the sinewave at input and the one at the output). You may have also to play slightly with A2 as well to reduce gain if you have saturation on both the positive and negative crests of the output sinewave.
  7. Next, turn P1 fully counter-clockwise (no CV). Adjust A2 in order to completly mute the output signal.


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