The PreenFM2 brings the old FM synthesis in a small open-source modern DIY box



The Plexi case :



Today’s technology in a small box.
In addition to regular FM synth features you’ll get (firmware 2.01) :

  • 4 independent instruments. Each of them has:
      • Powerful arpeggiator (Mutable-Instruments opensource algorithm).
      • 1 effect Slot (chose among 32 filters such as LP, HP, formant, crusher…)
      • 1 gate effect
      • 4 rapid access performance parameters
      • The 4 instruments can be saved all at the same time in combo presets.
      • Each instrument has its own modifiable midi channel. They can share the same for FAT quadruple timbres notes.
      • Modifiable number of allocated voices… Between 1 and 14.
      • 28 FM algorithms from 3 to 6 operators
  • Up to 14 voices of polyphony (8 if you use 6 op algorithms). Each voices has:
      • 7 low frequency modulators (3 LFOs, 2 enveloppes, 2 step sequencers).
      • 12 rows matrix : 16 sources, 32 destination (LP, HP, gate, stereo, MI, attack…)
      • Arpeggiator, LFOs and step sequencers synchronizable on external midi clock or internal clock.
  • Operator features:
      • 7 builtin waveforms + 6 user waveforms read from the usb drive.
      • Stereo panning (at the carrier operator level)
      • 8 envelope parameters per operator (DX7 like)
  • Direct Scala scale file loading for microtonality. Up to 128 Scala scales selectable from the preenfm2.
  • Modular Randomizer
  • USB all the way
      • Midi over USB
      • USB drive: huge preset banks: 64*128 presets, 8*128 combos, 256*32 DX7 presets.
      • The USB drive holds your preset banks, you scala scale files, your user waveform files.
      • Easy firmware upload and flash.
      • USB powered
  • Comprehensive user interface and associated to a 4×20 characters display for easy preset edition
  • Small, portable and easy to build (no SMD)
  • Mac/Linux/Windows open-source preset Editor : standalone and VST

preenfm2 Editor       preenfm2 Editor


Know you hardware : 100% open source (compiled with GNU toolchain) and  open hardware (only very standard components).



Other features :

  • Can import DX7 sysex banks (just put them on the usb stick)
  • Glide possible for instrument(s) with number of voice set to 1
  • Midi through Din5 or USB
  • Can be powered by USB or 7.5V-9v 2.1mm DC IN
  • Boots in 2 seconds
  • Al very standard components
  • 2 * double 12bits DAC (mcp4922) => 18 bits stereo output
  • Single simple pot to control stereo volume
  • Sample rate 38Khz (or 42Khz with overclocked firmware)
  • Custom bootloader with 3 ways to upgrade firwmare: Usb stick, sysex through Din5 or DFU.