Sequential just brought back polyphonic aftertouch for the first time in 40 years, and they did it on a four-voice analog synth that costs under a thousand dollars—which shouldn't be possible, but here we are.
The Fourm packs genuine Prophet-5 voice architecture into a compact 37-key slim-key keyboard, giving you four independent analog voices with dual oscillators per voice, each capable of simultaneous waveform selection. You get the classic Prophet sound through a resonant 4-pole low-pass filter with bass compensation and feedback drive for added edge, two ADSR envelopes modeled after the Prophet-5's response curves, and a single LFO with nine waveform options including noise variants. The control layout follows a knob-per-function philosophy with a Pro-One style modulation matrix, keeping everything intuitive and hands-on. Oscillator B can operate in low-frequency modes to function as a second modulation source, and both oscillators support classic Prophet-style sync.
What really sets the Fourm apart is that polyphonic aftertouch keybed—it lets you apply per-note pressure for guitar-style bends, individual voice swells, and articulations that would be impossible on a standard keyboard. The sequencer is where things get genuinely creative: it records up to 64 steps with support for chords, rests, ties, and acid-style per-note glide, and you can even route the sequencer data to modulate the filter or other parameters instead of just pitch. There's also a six-mode arpeggiator with octave range and repeat controls. The all-steel chassis keeps things solid despite the compact footprint, and the whole instrument runs a 100 percent analog signal path with no digital processing in the audio chain.
The community response has been enthusiastic—players appreciate that Sequential managed to deliver genuine polyphonic aftertouch expression and four-voice polyphonic depth without compromise, making it genuinely expressive for modern synthesis work while staying true to classic analog character.
