Fourm delivers four genuine voices of Sequential analog sound, built on the legendary Prophet-5 voice architecture—right down to its characteristic envelope response curves. With dual oscillators offering simultaneous wave selection and a classic 4-pole low-pass filter with bass compensation, Fourm captures the warmth and punch that shaped a generation—and takes it to the next level.
Fourm’s analog voice path is built around a modern oscillator chip inspired by the design used in the original Prophet-5 Rev 2. It delivers the same rich, musical tone as its vintage predecessor, now enhanced by the benefits of contemporary engineering — improved stability, reliability, and consistency. It’s the perfect foundation for Fourm’s 100% analog sound.
Fourm’s analog 4-pole lowpass filter chip is based on a classic design known for its rich, organic tone and musical resonance. The modern implementation faithfully preserves that sonic character while adding bass compensation. Now you can crank the resonance without sacrificing low-end power — keeping your sound full, bold, and unmistakably analog.
From its solid steel chassis to the custom-engineered Tactive slim-keys keybed with responsive polyphonic aftertouch, every element of Fourm was designed to deliver a fully integrated, high-performance playing experience. It’s a no-compromise, all-analog instrument, built for the next generation of synthesists. Custom-designed by Sequential, the Tactive™ keybed features 37 slim-keys tuned specifically to complement Fourm’s analog synthesis engine. And for the first time in 40 years, Sequential has returned to polyphonic aftertouch, an incredibly expressive performance feature that brings per note articulations to your fingertips.
Fourm’s modulation section is inspired by the legendary Sequential Circuits Pro-One, a highly sought-after classic monosynth that has propelled the bass lines of synthpop for decades. Explore the immediacy and flexibility of this hands-on modulation matrix and let your latest sonic inspirations take Fourm.
Fourm’s arpeggiator responds to your playing with inspiring musical results. Need a three octave setting with a dotted 8th note step value to create cascading, syncopated patterns? Fourm can do that and more. With re-latching, repeat settings, and six modes of interaction, the arpeggiator is a powerful tool for spontaneous composition and performance
Tucked into the arpeggiator section, Fourm’s polyphonic step sequencer is a creative powerhouse. Yes, it can play back musical phrases — but it can also be used as a modulation source, perfect for triggering rhythmic filter patterns and more. With support for chords, ties, rests, Acid-style per-step glide, and deep modulation routing, the sequencer transforms Fourm into a dynamic, hands-on composition tool.
Specifications
- 22.13? L x 9.88? W x 2.75? H (56.2 cm x 25.1 cm x 7.0 cm)
- Weight: 8.76 lbs. (3.97 kg)
- 12V DC 1.2A power supply, center-positive (included)
- Power supply can be plugged into an AC outlet capable of supplying from 100 V to 240 V at 50 Hz/60 Hz
- 14 Watts maximum power consumption
