Mutated: Module Tester

Mutated: Module Tester - A DIY Module Tester PCB - the most essential project in DIY. In our not-so-humble opinions.

This is a PCB useful for Eurorack, but not set in any mounting format.

Availability: In stock




Settings reference

Clock signal generator

  • Tempo is the tempo of the clock, in beats per minute.
  • Resolution is the number of clock ticks per beat. For example, a tempo of 120 beats per minute with 8 ticks per beat corresponds to a clock frequency of 960 ticks per minute (16 Hz).
  • Pulse is the duration or duty cycle of a clock pulse.
  • MIDI allows the clock rate to be controlled by an external computer or sequencer.

Gate signal generator

  • Period is the period of the signal.
  • Pulse is the duration or duty cycle of a gate pulse.
  • MIDI allows the gate signal to be generated from an external keyboard. In gate mode, the signal is high whenever a key is pressed on the keyboard. In trigger mode, a pulse is emitted every time a key is pressed – irrespectively of the duration of the note.

Control Voltage generator

  • Mode controls the output waveform: triangle, square, ramp up, ramp down, sine, 1 octave arpeggio (alternates between 1V and 2V), 2 octave arpeggio (alternates between 1V and 3V), chromatic scale (goes from 1V to 2V by 1/12V increments).
  • Period controls the period of the generated signal or sequence.
  • Range controls the amplitude and polarity of the signal: bipolar signals with a 2V, 4V or 10V amplitude; unipolar signals with a 1V, 2V or 5V amplitude. This setting is ignored when one of the arpeggio/scale modes are selected.
  • MIDI allows the voltage produced by this generator to be controlled by a MIDI message from an external keyboard.

Audio generator

  • Shape selects one of 4 waveforms: saw, square, triangle, sine wave.
  • Frequency selects the signal frequency. A few fixed frequencies are available, the remaining values are musical notes.
  • Envel. allows an external signal to “shape” the tone produced by this generator. In gate mode, the signal is on whenever the signal at the Gate In input is high. In trigger mode, the signal has a decreasing envelope, which is retriggered on raising edges of the Gate In signal.
  • MIDI allows the audio generator to be played from a keyboard.

Audio input

The encoder selects between 3 units:

  • Frequency (Hz)
  • Note and detuning (MIDI standard + cents)
  • Interval. In this mode, the musical interval between the current stable note and the previously played note is measured. This interval is expressed in cents. 1 octave = 1200 cents.

Gate input

The first line displays either the period, frequency, and tempo of the incoming signal.
The second line displays either the duty cycle, or the duration of the positive edge of the signal.

Note that the Gate Input LED blinks with the input signal.



NOTE:  All Mutated modules are designed by Olivier Gillet, and are CC-BY-SA.  

Ground rules:

  • Do NOT ask on the mutable forums or email Mutable Instruments for help.  There is literally ZERO support offered from those channels - don't be an ass.  A number of Facebook groups exist to help with DIY builds, and we're happy to help as well.
  • Do NOT (re)sell these, passing them off as factory modules.  Seriously - don't be an ass.
  • Do NOT be totally scared of SMT.  If you haven't done it before, it's off-putting, we get it - but give yourself a chance.  Learn something.  That's what (we think) DIY is all about.  We're keeping the prices on these low enough that you can afford to try and fail!
  • DO have a ton of fun building them, and use them to create awesome sounds.  Then go buy a Mutable Instruments module and SUPPORT Olivier's designs, directly.

Specs & Downloads

Specs & Downloads

Manufacturer Modular Addict
Depth No
+12V No
-12V No
+5V No
Additional Resources Mouser BOM


Customer Reviews (3)

Excellent addition to the toolboxReview by revel8or
This build required no unobtainum or SMD parts. The usual places of Mouser, Tayda, Digikey, etc. carry everything required.

For people who are getting in to populating PCBs or starting completely from scratch with a breadboard, this module solves many issues by giving you a gate, and predictable sources for waveforms.

It is not a replacement for an oscilloscope or multimeter, but it is equally important. This should be the first module PCB that you populate. It requires only a multimeter for calibration, but you should have an oscilloscope if your are building an oscillator...

I have to disagree with Boston, I think that this is a perfect starter project. It has no tricky soldering points, where the finest density is around the pins for the IC sockets. It is perfect for practicing solder techniques. It is very clear as to where every component fits. The IC can be purchased already programmed, so you don't have to worry about that, either. Be sure to remember that it requires a 12v AC adapter, not a 12v DC adapter for power.

I do agree with Boston's points about not risking already functioning (and probably pre-built, expensive) modules for testing *and* his point about building a box for it. It really needs to have a box. I learned the hard way many years ago that no matter how clean you *think* your work station is, you might miss the stray resistor wire laying in wait to screw up your build when power is applied. ;)

Good luck! (Posted on 4/29/2017)
Get oneReview by Troy
Large BOM, but a fun build. Do yourself a favour and custom build a case for it as well - make something ugly but functional. As Boston Modular says, you need one. When I realised the risk I was doing of plugging in something I'd sourced and built into my full setup, I stopped building until I got one of these. (Posted on 2/17/2017)
essential if you're building your own modulesReview by Boston Modular
This is not a project for a novice. Just sourcing the parts takes some skill.
But when you've built a few modules and want to get to the point where everything you build works as designed, you need test equipment.
This board is just as important as an oscilloscope, maybe more so.
Don't risk working modules to test your latest builds. (Posted on 8/10/2016)

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