YuSynth MiniMoog Transistor Ladder VCF Module Bare PCB

(£19.15 UK, incl VAT)
25 g
Out of stock

YuSynth MiniMoog Transistor Ladder VCF


A bare double sided PCB 75x100mm (no need for the wire jumper links shown on the PCB layout) for the Yusynth MiniMoog transistor ladder 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 MiniMoog Transistor Ladder VCF project page for detailed information including Yves panel layouts but a summary is shown below.

Erratum for PCBs dispatched before August 2021

We have spotted a few of errors on the YuSynth designed PCB, nothing serious though:

  • R31 next to T1(T2 see below) is incorrectly labelled on the PCB, it should read R33
  • U2 is U1 and U1 is U2
  • Rxx27 is R31 (56k)
  • T2 is T1 and T1 is T2


Well, it was meant to be! Yves Usson could not possibly avoid building a clone of this very successful and famous filter: the Minimoog VCF!
This filter has a sound of its own that contributed to the success of many songs during the 70s and 80s.

The aim here was to design a quite faithful copy of this mythic filter while using components that minimize the burden of selecting a great number of matched transistors. This is why he used cheap transistor arrays (CA3046). As for all the other filters of the YUSYNTH project, he has added an input and an output buffer to adapt this filter to the input and output levels of his modular system.
Because, the YuSynth power supply standard is +15/-15V, some values of resistors had to be modified.

NOTE: for Eurorack a pair of jumper must be add and the values of resistors R24,R26,R27 must be changed.

The PCB can accept a choice of three types of power connector, it can be either a Synthesizers.com 6 pins MTA connector, a MOTM 4 pins MTA96 connector or a 10-pin Eurorack connector.
The module is designed to work with a +15V/0V/-15V PSU


Click on the schematic thumbnail above for the circuit diagram.

Basically the circuit is built around the original core of the EMS filter, though Yves had to change some resistor values to compensate for the fact that the active components (NPN,PNP and JFET) are modern counterparts and some of their characteristics are different from the original parts.
The major additions are : a quadruple OPA that is used to buffer the various inputs (audio, CVs) and the output. The values of the resistors of these buffers may be adjusted to audio and CV levels of any modular system. Next, he introduced a voltage control input of the RESONANCE. Finally, a 78L12 and a PNP transistor to convert the power supply levels from +15V/-15V to +12V/-9V .

NOTE : the value of R47 can be changed to adjust the output level as see fit.




The wiring schematic image in the above thumbnails show the panel wiring to the pots and sockets etc. Note that the PCB silk screen has T1 and T2 swapped over. T2 and T3 presets pins are a rather tight fit in the PCB so care is needed when being inserted.

Setting and Trimming

V/Octave tracking :

  • Apply 0.000V to the V/Oct input
  • Turn the frequency knob fully counter-clockwise in order to measure 0mV at the base of Q1 (node between R9 to R11)
  • Apply 1.000V to the V/Oct input
  • Adjust T1 in order to measure 18.2mV at the base of Q1
  • Apply 5.000V to the V/Oct input
  • Check that you have 91.0mVat the base of Q1, if not adjust T1
  • Apply 0.000V to the V/Oct input
  • Set the filter to auto-oscillation (EMPHASIS turned fully clockwise)
  • Connect a keyboard (CV/GATE) to the V/Oct input
  • Play a tune and check the goodness of the tracking
  • Slightly adjust T1 to achieve a good chromatic tracking.

Frequency range :

  • Apply a sinewave with frequency 32Hz to the audio input
  • Emphasis potentiometer to minimum resonance (fully counter-clockwise)
  • Turn the frequency knob fully counter-clockwise
  • Adjust T2, in order to mute the 32Hz signal.
  1. Emphasis :
    Adjust T3 in order to reach auto-oscillation near 95% of the full range of the EMPHASIS pot.

Parts List

The parts list below is direct from the YuSynth website.

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 Value Part No. Qty
U1,U2 CA3046 Intersil, CA3146 and CA3086 are possible substitutes 7212-505 2
U3 TL072 7212-542 1
Q1 BC557 7212-403 1
Q2,Q3,Q4,Q5,Q6,Q7 BC547 matched by pairs 7212-495 3
R1,R2 10 ohms 7163-007 2
R25 22 ohms 7163-013 1
R17,R19,R20,R21 150 ohms 7163-031 4
R29 180 ohms 7163-033 1
R14 220 ohms 7163-035 1
R18,R22 330 ohms 7163-039 2
R12,R15 470 ohms 7163-043 2
R34 680 ohms 7163-047 1
R16,R28,R33, R26* 1K *1k2 for +15V/-15V PSU 1K for +12/-12V PSU 7163-051 4
R26* 1.2K* for +15V/-15V PSU 1K for +12/-12V PSU 7163-053 1
R11 1.8K 7163-057 1
R6 10K 7163-075 1
R23,R30 47K 7163-091 2
R5,R31 56K 7163-093 2
R7,R8,R9,R13 100K 7163-099 4
R3,R4,R32 120K 7163-101 3
R10 150K 7163-103 1
R24*,R27* 220K *270k +15V/-15V PSU 220K for +12/-12V PSU 7163-107 2
R24*,R27* 270K* +15V/-15V PSU 220K for +12/-12V PSU 7163-109 2
C14 100pF 7212-734 1
C4,C5,C6,C7 47nF matched quads to 1% 7212-792 1
C13 100nF 7212-749 1
C9,C10 220nF 7212-750 2
C3,C11,C12 10µF/50V 7213-119 3
C1,C2 22µF/50V 7213-120 2
C8 220µF/25V 7213-111 1
T1 500 ohms 10/15 turn trimmer 7212-853 1
T3 1K trimmer 7212-803 1
T2 10K trimmer 7212-806 1
P4 10K lin 7300-230 1
P1,P2 50K log 7300-025 1
P3 50K lin 7300-250 1
P5 50K reverse audio potentiometer (ALPHA) 7300-110 1
Jk1,Jk2,Jk3,Jk4,Jk5,Jk6 female jack socket 7212-206 6

Hi there, I'm having trouble getting it working. I'm using eurorack layout, but it seems the jumpers are now on the PCB? I've tried tracing an input ramp signal on the input, I get to R6 / C3 at which point the signal vanishes. It looks like the electrolytic (C3) is blocking the it. I'm fairly new to all this, but is an electrolytic a good choice of cap to put on a signal path? I can't get it to self-resonate either... Could you provide any troubleshooting tips? Many thanks.

Asked by Simon Wibberley | 10/03/2020, 00:07 | 3 answer(s)

Hi, the Ca3046 has only 15V Vceo (Collector-Emitter Voltage) referring to the Datasheet. At U2 the Transistors are between +15V and -15V. E.g. (pin6,7,8). If this Transistor is open, (Base is grounded with 47K), no current flows and between pin 7 and pin 8 (Emitter,Collector), so 30V are applied. My Ca3046 is now completly dead (U2). Or am i missing something ? - Lennard

Asked by Lennard Kreuzer | 11/02/2020, 21:28 | 1 answer(s)

You mention additional 2 'jumpers' for 12v operation I can't see or find reference to these. Dave

Asked by David Sampson | 27/10/2019, 10:46 | 1 answer(s)

Hello, I just received my module with the components, thank you so much. I've got a +/- 15V power supply And I want to make sure I put on the right components. Are the PCB values designed for +/- 15v? regards, Paul

Asked by Paul Schaffner | 19/06/2019, 22:30 | 1 answer(s)

The PCB has the same basic layout as the pics on your site buy if you look at the values of the components and their corresponding reference numbers the board is completley different. Some of the refrence numbers on the board don't even exist in the website pics or the parts list sheet (like Rxx27 at the top of the board) Is there a revised reference list?

Asked by Jay Shriver | 23/09/2018, 01:24 | 1 answer(s)
A smooth chewy toffee filter with a smooth resonant bite. Wide ranging and delicious, would suggest using the largest Moog type knobs you can get your hands on for authentic 1950's filter sweeps on a Mars orbital space station type studio set up. Essential module.
This PCB is a work of art - beautifully produced, clear screenprint. It almost seems a shame to cover it with components - but I'm going to anyway :-)
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