Sequential Fourm 4-Voice Analog Synthesizer with Polyphonic Aftertouch

Perform Expressively - The Sequential Fourm 4-Voice Analog Synthesizer with Polyphonic Aftertouch

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 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.

SPECIFICATIONS

Synthesis

• Oscillators: All oscillators have simultaneously selectable waveforms, including LFO
• Oscillator B: Supports low frequency modes
• Sync: Classic Prophet-style
• Filter: 4-pole resonant lowpass with bass compensation
• Feedback: Aggressive drive circuit
• Envelopes: 2 ADSR envelopes
• Sequencer: Glide per step supported

In/Out

• Main Output: Mono (1/4-inch jack)
• Headphone Output: Mono (1/4-inch TRS phone jack)
• MIDI: In, out, and thru ports
• USB: Bidirectional MIDI communication
• Pedal Input: Footswitch/expression

Power

• Power Switch: Separate
• Power Supply: 12V DC 1.2A, center-positive (included)
• AC Compatibility: 100 V to 240 V at 50 Hz/60 Hz
• Power Consumption: 14 watts maximum

Physical Specs

• Dimensions: 22.13 x 9.88 x 2.75 inches (56.2 x 25.1 x 7.0 cm)
• Weight: 8.76 lbs. (3.97 kg)
• Security: Anti-theft slot

We are Musictoner Musictoner

Since 1958, Chuck Levin’s Musictoner has been the trusted destination for musicians and audio professionals across Maryland, Virginia, and Washington, D.C. Family-owned and operated, our legendary music store delivers Everything in Music®—from instruments and recording gear to pro audio, rentals, and repair services.

Our team of musicians and industry experts lives and breathes gear, helping you build the perfect setup for your next performance, studio session, or installation. As an authorized dealer for top brands, we also offer our award-winning CHUCKSCLUSIVE line—exclusive, limited-edition instruments and collaborations recognized with the NAMM Top 100 Dealer Innovation Award for redefining what a music retail experience can be.

Chuck Levin’s isn’t just a store—it’s a community built by players, engineers, and creators who share a lifelong passion for sound. Stop by our legendary Wheaton, MD showroom or contact us anytime for expert advice, product questions, or the best possible deal on your next piece of gear.