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Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch

Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch

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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.
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  • Details
  • Features
  • Tech Specs
  • Reviews

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 the 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.

More Information
Product Name Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch
Brand Sequential
Condition New
MPN SEQ-3900
UPC 855346000487
Shipping Option Free Shipping to the Continental U.S.

What's in the Box?

  • Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch
  • 2V DC 1.2A Power Supply

FEATURING

  • 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

SYNTHESIS

  • All oscillators have simultaneously selectable waveforms – LFO too
  • Oscillator B supports low frequency modes
  • Classic Prophet-style Sync
  • 4-Pole resonant lowpass filter
  • Feedback with aggressive drive circuit
  • 2 ADSR envelopes
  • Sequencer supports glide per step

In/Out

Main Output Mono (1/4” jack)
Headphone Output Mono (1/4” TRS phone jack)
MIDI In, out, and thru ports
USB Bidirectional MIDI communication
Footswitch/Expression Pedal Input Yes

Power

Power Switch Separate power switch
Power Supply 12V DC 1.2A, center-positive (included)
AC Compatibility 100 V to 240 V at 50 Hz/60 Hz
Maximum Power Consumption 14 Watts

Physical Specs

Dimensions 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)
Anti-Theft Slot Yes

Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch

Details

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 the 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.

More Information
Product Name Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch
Brand Sequential
Condition New
MPN SEQ-3900
UPC 855346000487
Shipping Option Free Shipping to the Continental U.S.

What's in the Box?

  • Sequential Fourm 37-Key 4 Voice Analog Synthesizer w/ Polyphonic Aftertouch
  • 2V DC 1.2A Power Supply
Features

FEATURING

  • 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

SYNTHESIS

  • All oscillators have simultaneously selectable waveforms – LFO too
  • Oscillator B supports low frequency modes
  • Classic Prophet-style Sync
  • 4-Pole resonant lowpass filter
  • Feedback with aggressive drive circuit
  • 2 ADSR envelopes
  • Sequencer supports glide per step
Tech Specs

In/Out

Main Output Mono (1/4” jack)
Headphone Output Mono (1/4” TRS phone jack)
MIDI In, out, and thru ports
USB Bidirectional MIDI communication
Footswitch/Expression Pedal Input Yes

Power

Power Switch Separate power switch
Power Supply 12V DC 1.2A, center-positive (included)
AC Compatibility 100 V to 240 V at 50 Hz/60 Hz
Maximum Power Consumption 14 Watts

Physical Specs

Dimensions 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)
Anti-Theft Slot Yes
Reviews