Twisted Electrons has opened pre-orders for FLEXFM, the hybrid groovebox it showed at Superbooth 2026 and then said little about for nearly six months. Full specifications are now published, and the French builder says units ship before the end of the year.
The headline is eight voices of FM synthesis with analogue filters and sampling. The actual design decision worth noticing is narrower than that, and more interesting.
The operator slot is the trick
Each voice has four operators. That is the classic configuration — it is what a DX100 or a Volca FM gives you, and you can use FLEXFM that way.
But the operators are not restricted to oscillators. Each one draws on a library of more than 30 operator engines, and that library mixes synthesis and playback in the same list:
- classic waveforms
- wavetables
- macro oscillators based on the open-source Mutable Instruments Braids
- NES-inspired engines
- wave drawing
- sample playback engines — slices, sampler, wavescan, repitching
So an operator can be a sine wave frequency-modulating another operator, in the textbook way. Or it can be a sample slice being frequency-modulated by a wavetable. The hybrid is not a signal-path afterthought where a sampler section sits next to a synth section; it is at the level of the operator, which is where FM actually happens.
Each operator carries its own level, envelope, ratio/speed, start/end, fine-tune, pitch fall and feedback.
The matrix is morphable
The four operators meet in a modulation matrix that offers frequency modulation, amplitude modulation, ring modulation and oscillator sync. Routings can be selected outright — or morphed, using the large X/Y slider on the left of the unit.
Morphing between algorithms rather than switching between them is the part that is hard to do on vintage FM hardware, where the algorithm is a numbered preset and moving between two of them is a discontinuity. Sampling into the unit happens through the audio input, or by importing a WAV file.
Analogue filter, then three digital ones
Every voice gets its own multimode analogue filter with 15 pole-mixed responses across low-pass, high-pass, band-pass and notch. Twisted Electrons’ Alex says the circuit takes inspiration from the Mutable Instruments four-pole “mission” filter — the second Mutable debt on the spec sheet, and a reminder of how far that open-source work has travelled since the company wound down.
Three digital filter types sit beyond the analogue one for sound design that the analogue circuit cannot reach:
- CROQUETTE — described as a crisp filter
- ZMORPH — a Z-plane-inspired digital morph filter
- ORACLE — moves through a three-dimensional space of peaks and notches
Each is fully adjustable, with the usual controls plus a dedicated ADSR, velocity response, key tracking and further modulation options.
Modulation you can see
On top of the per-operator and per-filter envelopes, each voice has four LFOs. They run as conventional multi-wave LFOs, or as an ADSR contour, or as a shape drawn by hand with the joystick. All four can target different destinations, support sync, and offer loop or trigger behaviour.
Crucially, Twisted Electrons says they are not buried in menus. The panel carries knobs with LED position indicators and tactile sequencer buttons, which is the company’s long-standing answer to the problem that makes FM unpopular: not that the maths is hard, but that on most hardware you cannot see what any of the numbers are doing.
FLEXFM joins a catalogue — TWISTfm, BlastBeats, MEGAfm II, TherapSID, AY3 MKII — built almost entirely on reanimating old silicon. This one is the first to put sampling inside the operators.