“World’s Smallest MIDI Synth” Puts A Powerful FM Synth In Your Pocket

H-Pi Instruments has teamed up with mitxela on FLASH, described as “the world’s first and only very-tiny MIDI-powered polyphonic microtonal FM synthesizer”.

This little 16-voice wonder fits in your pocket and doesn’t require a power supply. It’s powered by the output of your MIDI controller.

And while it’s a minimal synth, it offers 16-voice polyphony, MIDI-CC control, microtonal tuning and more.


  • Tuning
    • Unlimited pitch General MIDI microtuning up to 16 voices polyphony
    • 16 full range programmable tunings of 128 notes each = 2048 programmable fixed pitches
    • voluntary pitch bending from retuned fixed-pitch centres
    • Largest tuning error ~ 0.006 cents
  • Synthesis
    • FM synthesis engine
    • Controllable via MIDI CCs
  • Voice Modes
    • POLY: 16 voices, one oscillator per voice, mono LR audio output
    • POLY-STEREO: 8 voices, one oscillator per voice, stereo audio output
    • MONO: 1 voice, 16 oscillators layered, mono LR audio output
  • Inputs and Outputs
    • MIDI DIN input (for MIDI and power)
    • 3,5 mm stereo headphones audio output

Pricing and Availability

The FLASH synthesizer is available now with an intro price of 129.99 € (normally 159.99 €).

23 thoughts on ““World’s Smallest MIDI Synth” Puts A Powerful FM Synth In Your Pocket

  1. Wow. I’m really impressed by how much they can make happen both in a small package and with very little power. Very cool

  2. Was not expecting the lecture on low-power circuit design considerations in the 2nd half. It doesn’t get much nerdier than this, and I mean that in a good way.

    1. YES! it does freaky stuff that only FM big guns do, including microtuning, fake reverb, true stereo, true pitchbend.

    1. that is my thought – kinda wish it had like a micro usb on the side so that you could plug it in and easily write patches via an editor too

    2. Yes you can save your own patch presets and microtunings over USB. The synth comes with a USB-to-UART programmer which isn’t shown in the video. He shows instead an adapted FTDI programmer which we used during development. Pictures of the actual UART programmer will be up on the website soon (November).

  3. Looking at it from a synthesist’s point of view, is it purely sine waves, or are there other wave shapes? How many bits? How many operators, and what are the algorithms? Inquiring minds want to know…

    1. According to the guy who wrote the synth (mitxela), it’s got two algorithms. First is 2-op carrier-modulator FM, selectable waveforms (according to the video), plus a LFO. The second algorithm he calls “PseudoFM” and is something he invented, without much description of how it works other than that there’s no ratio. He says there’s room for “dozens” of additional algorithms, and he hasn’t written them yet, but when he does the unit can be upgraded over the MIDI connection. He also notes it has a 12 bit DAC. Firmware updates and table and algorithm updates are done by his overloading the MIDI pins to connect to a UART to USB bridge, which it seems to come with (UART-programmer).

  4. This is great! Yeah, so I just ordered one. Can’t help myself! For nerd candy like this, it’s a gotta-have!

    At 34:35 he takes it apart and shows the guts. Not much there, of course. Flexible PCB, and a honking big capacitor. Stuff like this always points up how far we’ve come. (Yes, I used to take vacuum tubes down to the store and use the tube tester.)

  5. I’m wondering if there would be a way to plug this directly into a mixing board and send just the midi wirelessly (yet still power it).

  6. Fascinating journey! Not sure I need that, but it is awesome for what it is. No batteries needed and tiny. Although, you do need a midi-controller to play it. Could be great addition for a portable setup.
    Can you make effect units in similar fashion to go along with it?
    It does remind me a bit of the Axoloti board which I love playing with.

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