Sequential Fourm: The affordable analog polysynth that brings prophet DNA to a wider audience

Its strengths are easy to hear in brass stabs, compact pads, sync leads, basses, plucked sequences, and expressive monophonic lines. Because the voice architecture is relatively focused rather than sprawling, sounds tend to arrive quickly. The Fourm does not encourage endless menu-based drift; it encourages making decisions. That gives it an unusually immediate musical identity for a contemporary synth at this price.

A large part of that character comes from the interaction between its dual analog oscillators, Prophet-lineage filter behavior, feedback circuit, and modulation design. The feedback stage adds thickness and edge without pushing the instrument into gimmick territory, while the Vintage parameter can move the sound away from clean modern stability toward more irregular, imperfect motion. Oscillator B’s low-frequency modes also matter more than they may seem on paper, because they let the synth generate per-note modulation behavior that can sound more animated and less standardized than a single global LFO.

The result is a synth that leans vintage in musical effect, but not in a museum-piece sense. It is not trying to impersonate one exact year of Sequential history. It sounds more like a practical compression of several eras of Sequential design into a modern, accessible performance instrument.

Features and architecture

• Manufacturer: Sequential
• Year introduced: 2025
• Production years: 2025–present
• Synthesis type: 100% analog subtractive synthesis
• Category: Compact polyphonic analog keyboard synthesizer
• Polyphony: 4 voices
• Original price: Launch pricing was widely listed at $999 / £799 / €949
• Current market price: New U.S. pricing has recently appeared around $899.99; the used market is still forming and often sits uncomfortably close to new pricing
• Oscillators: 2 analog VCOs per voice; Oscillator A offers saw and pulse, Oscillator B offers triangle, saw, and pulse; multiple waveforms can be active simultaneously; adjustable pulse width; Oscillator B includes low-frequency modes; hard sync available
• Filter: Prophet-style 4-pole resonant low-pass filter with self-oscillation; bass-compensation behavior is highlighted in current manufacturer/retailer material
• LFOs: 1 main LFO with triangle, saw, reverse saw, square, sample-and-hold, random/noise-derived modes, and DC options; syncable to internal or external clock
• Envelopes: 2 ADSR envelopes
• Modulation system: Pro-One-inspired modulation matrix with 3 sources and 8 destinations, direct and mod-wheel buses, positive/negative modulation amounts, plus dedicated polyphonic aftertouch routing
• Sequencer / arpeggiator: Arpeggiator with multiple playback modes and octave ranges; 64-step note or modulation sequencer; glide-per-step functions available in sequencing
• Effects: No onboard effects
• Memory: 512 program locations across user and factory banks
• Keyboard: 37-note slim-key keybed with velocity and polyphonic aftertouch
• Inputs / outputs: Mono main output, headphone output, footswitch/expression pedal input
• MIDI / USB: MIDI In/Out/Thru plus USB-C for bidirectional MIDI
• Display: OLED display
• Dimensions / weight: 22.13” x 9.88” x 2.75”; 8.76 lbs / 3.97 kg
• Power: External 12V DC power supply; universal 100–240V operation

Strengths

• It delivers recognizably Sequential tone at a price point that changes who can realistically enter the brand. That matters more than a simple spec-sheet discount, because the instrument still preserves a strong sense of voice rather than sounding like a diluted badge-engineering exercise.
• The polyphonic aftertouch implementation is not an afterthought. It meaningfully changes how the instrument can be played, especially for leads, held chords, evolving stabs, and restrained performance gestures that would feel flatter on a standard budget polysynth.
• The interface is fast in the best Sequential tradition. The Fourm avoids both deep menu dependence and fake one-knob-per-function oversimplification. It is approachable without feeling stripped down.
• The modulation architecture is smart rather than bloated. Three sources and eight destinations may not look radical on paper, but the routing is musical, immediate, and genuinely useful in performance and patch design.
• The sound remains forceful even in a compact format. Brass, bass, sync tones, and short polyphonic phrases have authority, not just convenience.
• The feedback, vintage, and oscillator-low-mode behaviors expand the instrument beyond polite retro tones. They let the Fourm move from classic subtractive warmth into dirtier, more unstable, more animated territory.
• Its physical design supports portability without feeling disposable. The steel chassis and tightly focused panel layout reinforce the sense that this is a serious instrument, not merely a cut-down entry model.

Limitations

• Four voices is a real limitation, not a paper limitation. It affects voicing choices immediately, especially for sustained chords, two-handed playing, and arrangements that expect longer releases.
• The 37-note slim-key format will divide players. Some will value the portability and expressive response; others will simply want more room and full-size keys.
• There are no onboard effects. For some players that keeps the voice pure; for others it means the instrument depends more heavily on external processing to reach finished-production polish.
• Its architecture is focused rather than expansive. If you want deep multitimbrality, lavish voice counts, layered digital complexity, or a broad workstation-style palette, this is the wrong synth.
• The used market has not settled yet. Because the model is still new, second-hand pricing can be irrationally close to discounted new pricing.
• Its strongest identity is also a boundary. The Fourm is excellent at sounding like a focused, characterful analog synth, but it is not trying to be an everything-machine.

Historical context

The Fourm arrived in September 2025 at an especially revealing moment for Sequential. By that point, the company had already spent years reasserting its authority through instruments such as the Prophet-5 Rev4, Prophet-6, Trigon-6, and Take 5, while also operating within the larger Focusrite group. The question was no longer whether Sequential could still build premium instruments. The question was whether it could move downward in price without surrendering the design values that made the brand matter in the first place.

That is the context in which Fourm becomes more than a compact polysynth. It is a market statement. It responds to a landscape already crowded with affordable analog options, but it does so by emphasizing something many lower-priced competitors still treat as secondary: a strong inherited sound identity, a performance-first control system, and polyphonic aftertouch that is designed as part of the instrument rather than bolted on as a luxury feature.

It is also not a reissue in the strict sense. The Fourm openly references the Prophet-5 and Pro-One, yet it does not reenact either one literally. Instead, it works as a reinterpretation: Prophet-like voice architecture, Pro-One-style modulation logic, and a newly designed expressive keybed in a format shaped by present-day price pressure and portability demands.

Legacy and significance

The Fourm matters because it reframes what an “entry point” can be for a heritage synth brand. Too often, entry-level products are exercises in removal: fewer controls, fewer ideas, less personality, less reason to care. The Fourm is more interesting than that. It narrows the format and the voice count, but it keeps the aesthetic logic intact.

Its biggest significance may be that it joins two things that are often separated in the current synth market: affordability and expressive seriousness. A sub-$1000 analog polysynth is no longer shocking on its own. A sub-$1000 analog polysynth with a custom polyphonic-aftertouch keybed, a recognizably Sequential voice, and a modulation structure that actually encourages playing instead of menu administration is far more unusual.

It also broadens the meaning of modern Sequential design. Rather than presenting the brand only through large-format prestige instruments, Fourm argues that portability, accessibility, and lower cost do not have to imply genericity. In that sense, it may prove important not only as a product, but as a strategic template.

Artists, users, and curiosities

Because the Fourm is still a very recent instrument, it does not yet have a long, settled canon of famous records attached to it in the way older Sequential instruments do. That does not make it culturally anonymous; it just means its story is still being written.

One meaningful early indicator is the factory sound-design roster. Sequential’s own documentation credits contributors including Robert Rich, Julian Pollack, Nick Semrad, Francis Preve, Gil Assayas, Chris Calcutt, Drew Neumann, and others. That matters because it frames the instrument through musicians and sound designers who understand how to make a compact analog synth feel broader than its raw voice count suggests.

A second curiosity is the keyboard itself. At a price where many brands would simply source an off-the-shelf compromise, Sequential made the Tactive keybed central to the product story. That decision reveals a lot about what the company thought Fourm needed to be. The instrument was not designed merely to imitate Prophet-style tone cheaply; it was designed to make expressive control part of the value proposition.

A third curiosity is historical: Sequential described Fourm as the company’s return to polyphonic aftertouch after roughly four decades away from building a synth around it in this way. That alone gives the model a stronger place in the company timeline than its modest price might initially suggest.

Market value

• Current market position: One of the clearest “serious but reachable” analog polysynths in the current Sequential lineup
• New price signal: It launched at aggressive pricing for the brand and has already appeared with U.S. discounts around $899.99, which strengthens its value argument
• Used market signal: Still immature; resale pricing often remains too close to new pricing, which suggests the market has not yet stabilized
• Availability: Generally available through major retailers and directly through Sequential, though direct sales have geographic limitations
• Buyer notes: The key buying question is not whether it sounds good, but whether you are comfortable with four voices and a 37-note slim-key format
• Support ecosystem: Strong for a new instrument, with official documentation, MIDI implementation files, factory sound banks, retailer stock, and a visible demo/tutorial footprint
• Ease of finding one: Easy to find new in major territories; used availability is thinner and less predictable
• Long-term position: Too early to call collectible, but it already looks unlikely to be ignored; its combination of price, polyphonic aftertouch, and brand identity gives it a stronger long-term profile than many budget polysynths

Conclusion

The Sequential Fourm is not important because it is cheap by general market standards. It is important because it is inexpensive by Sequential standards without feeling conceptually diminished. It compresses Prophet-derived tone, Pro-One-style modulation thinking, modern expressive control, and practical portability into a synth that feels coherent rather than compromised.

Its limitations are obvious and real: four voices, no effects, and a polarizing compact keybed. But those limitations are part of a design with a point of view. The Fourm matters because it proves that broadening access to a legacy sound does not have to mean flattening the legacy itself.