MicroMonsta tear-down

Audiothingies MicroMonsta

The Audiothingies MicroMonsta is probably the best polyphonic synthesizer available at the under $500 price. This synthesizer is a lot of fun to play and create with, and has a huge, clean sound. And quite frankly, it is capable of providing a sound pallet that matches any of the high end digital synthesizers from Novation or Korg.

Specs (copied from Audiothingies web site):

  • 8 voices of polyphony
  • 2 oscillators, 1 sub oscillator, 1 multimode filter, 3 envelopes, 3 LFOs, 6 modulation slots, 3 scalers, 1 lag operator per voice
  • 12 oscillator types + 30 (multi-sampled) wavetables (15 factory featuring both evolving sweeps and totally random wavetables + 15 user for your own creations)
  • 8 filter types
  • Detuning options (both per voice and per oscillator)
  • Arpeggiator with step pattern editor, slide and accent capable for 303-ish arpeggiated phrases
  • Modulation matrix
  • A chorder module allowing the generation of 4-note chords within a key/scale
  • Internal FXs
  • 384 preset slots to store your sound creations

The Micromonsta is not available anymore and has been replaced by the MicroMonsta 2. As I await my turn in line to obtain the newer version, I will use this time as a good excuse for finding out just what is inside the little box.

Opening the box is straight forward, as there are no screws holding it together. Just remove all of the knobs and pop up each side of the case panel


Case Panel section

This will reveal a single circuit card held onto plastic standoffs. Then remove the plastic nuts on the audio jacks. You can then take out the 7 screws that hold the circuit card in place.

PCB Hardware Side

Case base section


PCB Component Side

The MicroMonsta has 4 integrated circuits, from right to left they are:

  1. STM32F405 ARM2 microprocessor
  2. 6N137 opto-isolator for the MIDI I/O
  3. 24LC512 EEPROM used for storing presets
  4.  CS4354 Stereo DAC for the audio output.

What surprised me was how similar the design was to the PreenFM2, as it too uses the STM32405, the 6N137 and 24LC512. The difference being the Preen uses a different DAC with an analog opamp-filter section for the audio output. The MicroMonsta’s use of the CS4354 is a more simplified design, yet still has the same or better audio path due to the CS4354 having the buffering and filtering section built into the chip.

This is not a complicated design to build and I think it would have been nice to have the Micromonsta available as a DIY. Having said all that, what did we learn?

Well, the MicroMonsta is 100% software driven synthesis, so is there any difference between it and a VST? Maybe. But only with the DAC that the MicroMonsta uses. I will need to study the spec sheet a little more and evaluate the underlying buffering/filtering section. Differences could also depend on which sound card the PC was using with the VST, but that too would be DAC dependant.

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