Sequential Fourm 4-Voice Polyphonic Analog Synthesizer
Sequential Fourm is a compact analog synthesizer that invites you to play, shape and perform with unprecedented expression. With its legendary Sequential tone, hands-on modulation and uniquely responsive keybed, Fourm is a creative partner helping to bring your musical ideas to life.
- 37-note slim-key keyboard with polyphonic aftertouch
- Warm and organic, 100% analog signal path
- Intuitive, welcoming knob-per-function layout
- Pro-One style top-panel modulation matrix
- Prophet-lineage resonant filter with bass compensation
- Arpeggiator with sequencer mode
- 128 world-class presets
- Pro-quality, all-steel chassis
Legendary analog sound, reimagined
Fourm delivers four genuine voices of Sequential analog sound built on the legendary Prophet-5 voice architecture, right down to its envelope response curves. With dual oscillators offering simultaneous wave selection and a classic 4-pole low-pass filter, now enhanced with bass compensation, Fourm captures the warmth and punch that shaped a generation and takes it to the next level.
A new Fourm of expression
Fourm's 37-note slim-key keyboard features polyphonic aftertouch, unlocking expressive techniques like guitar-style note bends, solo voice swells and other nuanced articulations, completely transforming the experience of playing a modern analog polysynth.
Modulation you can touch
Inspired by SCI Pro~One, Fourm's top-panel modulation matrix puts deep sound design at your fingertips – no menu diving required. Route sources and destinations with a button press, visualize connections with color-coded indicators and build complex modulation paths in seconds. It's fast, intuitive and designed to keep you in the creative flow.
| Specification | Value |
|---|---|
| SKU | SEQ-FOURM |
| Model Name | Fourm |
| Vendor | Sequential |
| Aftertouch | Yes |
| Analog Digital | Analog |
| Built In Speakers | No |
| Included From Manufacturer | Power supply |
| Keys Weighted | No |
| Number of Keys | 37 |
| Key Size | Slim Keys |
| Midi | In, Out, Thru, and USB |
| Mono Poly | Polyphonic |
| MPN | SEQ-3900 |
| Product Unique Features |
|
| Key Action | Tactive synth action keybed with polyphonic aftertouch |
| Number of Patches/Programs |
512 program locations 120 factory presets |
| Voices of Polyphony | 4 |
| Oscillators per Voice | 2 |
| Sequencer | Arpeggiator includes sequencer mode |
| Arpeggiator | Yes |
| USB Port (to Host) | MIDI |
| Audio Outputs |
1/4" main output 1/4" headphone output |
| Control Connections | 1/4" footswitch or expression pedal input |
| Onboard Controllers |
Pitch bend wheel Mod wheel |
| Width | 22.13" |
| Depth | 9.88" |
| Height | 2.75" |
| Product Weight | 8.76 lb |
Sequential warrants that its products will be free from defects in materials and/or workmanship for one (1) year from the date of purchase. Please register your product online at at the Sequential website to establish the date of purchase. This is not a requirement for warranty service, but it will help expedite the warranty service process. See Sequential's website for more details.
Ground shipping is FREE to the 48 contiguous United States for orders $99 and up.*





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