Molten Music Technology’s Fourm Review: Sequential’s Little Box of Analog Mischief

Tiny Titan: Four Voices, Big Punch

Let’s not beat around the bush: the Sequential Fourm is a compact, four-voice analog synth that’s got more muscle than its size suggests. Robin from Molten Music Technology wastes no time pointing out that this is the most affordable Sequential in ages, sitting somewhere between a Pro 1 and a Prophet 5 in spirit. The build? Heavy, chunky, and with knobs that feel like they were designed for a tank—no wobbly plastic here. This thing’s got presence on your desk and in your mix.

Physically, the Fourm is a proper slab. The trim is a nice touch, and the overall feel is reassuringly robust. Robin’s not shy about calling out the slightly odd buttons and the resistance on those knobs, but it all adds up to a synth that feels like it could handle a few late-night studio accidents. It’s not cheap, and it doesn’t pretend to be. If you’re after a synth that looks and feels like a serious bit of kit, the Fourm’s got you covered.

No Effects, No Excuses

Here’s where things get interesting: the Fourm ships with zero built-in effects. None. Not even a token chorus or a splash of reverb. Robin’s take? That’s not a bug, it’s a feature. If you want a synth to do all your sound design heavy lifting, you’ll have to bring your own toys to the party. This forces you to get hands-on with your patches and stop hiding behind a wall of digital FX.

Sure, some folks will grumble, but Robin makes a solid point—most of us end up running our synths through plugins or outboard anyway. The lack of effects keeps the price down and the signal path pure. If you want to hear what the Fourm sounds like with effects, you’ll have to check out the video, because the difference is night and day. But the raw, unprocessed tone is where the Fourm’s character really shines.

Sound Palette: From Classic to Chaos

Don’t let the simple architecture fool you—the Fourm’s sound palette is surprisingly broad. Robin demos a stack of presets, including some from the new user bank, and the variety is impressive. From lush pads to punchy basses and weird, evolving textures, this synth covers a lot of ground for something so straightforward. Big up to the sound designers who squeezed so much out of a basic subtractive setup.

The real magic happens when you start building patches from scratch. The Fourm’s two oscillators, classic filter, and smart modulation routing mean you can go from vintage Prophet vibes to gritty, modern sounds without breaking a sweat. It’s not about endless menus or deep modulation matrices—it’s about getting straight to the good stuff. If you want to hear how wild it can get, the video’s jam-packed with sonic examples that text just can’t do justice.

"It is remarkably diverse, really, and that's immensely satisfying."

© Screenshot/Quote: Moltenmusictech (YouTube)

Aftertouch Antics and Firmware Fumbles

"The keyboard is immediately kind of slightly disappointing and irksome. But as you play with it, it all comes alive."

© Screenshot/Quote: Moltenmusictech (YouTube)

Let’s talk quirks. The Fourm’s keyboard isn’t full-size, and at first touch it’s a bit of a letdown. But give it time, and it grows on you—especially thanks to that polyphonic aftertouch. Robin calls it a pain in the arse, but admits it’s a sound designer’s dream. The aftertouch is everywhere in the presets, sometimes to the point of overkill, but it’s easy to dial back if you want a more restrained vibe.

On the flip side, updating the firmware is a proper headache. Sequential still relies on SysEx transfers, which feels like a throwback to the 1980s. Robin’s frustration is palpable—why can’t a modern synth just update via USB like everything else? Add in the lack of a free official software editor, and you’ve got a synth that’s all muscle on the outside but a bit clunky on the digital side. Still, once you’re past the faff, the Fourm’s hands-on experience is hard to beat.

Back to Basics: Subtractive Synthesis Done Right

The Fourm is a love letter to classic subtractive synthesis. There’s no FM, no wavefolding, no weird cross-modulation—just two oscillators, a low-pass filter, envelopes, and an LFO. Robin appreciates the simplicity: you’re not getting lost in endless options, you’re just making music. It’s the kind of synth that rewards tweaking and experimentation, not menu diving.

If you’re after vintage vibes and want a synth that slots into any setup without dominating the mix, the Fourm is a solid bet. It’s not trying to reinvent the wheel, and that’s exactly why it works. For the full flavour—especially the way it reacts to external effects—you’ll want to watch the video. Some sounds just can’t be described; they need to be felt. In a world of overcomplicated synths, the Fourm stands out by keeping it real.