French Boutique Builder NRSynth Unveils Analog Oberheim Four-Voice Clone, the Quatuor

The Oberheim Four-Voice has haunted vintage synth want lists for decades: four discrete SEM modules stacked into a single instrument, each with its own oscillators, multimode filter, and envelope, producing a sound that no plugin has convincingly replicated. French boutique builder NRSynth announced its hand-built clone, the Quatuor, on April 5, adding MIDI, a Eurorack-compatible patch bay with 3.5mm jacks, and a five-octave FATAR keyboard with velocity and aftertouch to an architecture the original never offered any of.

The core engine stays honest to Tom Oberheim's original layout: four SEM voices, each running two oscillators through a 12 dB multimode filter with the full SEM signal path intact. Stephen, the maker behind NRSynth, has gone further than simply replicating the voice count. Each oscillator gains a pulse-wave sub oscillator running one octave below VCO1 and an analog white noise source, features missing entirely from the vintage instrument. The modulation architecture is equally expanded: two envelopes include an option to switch release behavior modeled after the Sequential Pro-1, and the LFO section runs two parallel paths, an analog triangle LFO alongside a digital LFO offering eight waveforms, tilt control, and three frequency ranges with sync. A sample-and-hold generator rounds out the modulation sources.

The MIDI implementation, developed in collaboration with Jean-Luc Lartigue from ozoe, makes the Quatuor immediately usable in any modern setup without the workarounds that come with an original Four-Voice. The top panel's Eurorack-compatible patch bay opens the instrument to modular routing that vintage units cannot accommodate. An arpeggiator and sequencer are also part of the package.

Stephen has described the Quatuor as sounding "punchier" than some original Four-Voices, a claim he made at previous shows and will have the opportunity to back up at SynthFest France, running April 17 to 19 in Carquefou, near Nantes. The Quatuor's festival debut gives players a rare chance to evaluate a hand-built boutique clone against the 50-year-old standard it's designed to honor.

Pricing and firm availability remain pending, and NRSynth's hand-built production model points toward limited runs rather than any mass manufacturing. That reality shapes the buyer's calculus clearly. If you want Oberheim SEM character with stable tuning, modern MIDI, aftertouch, and patch points baked in from the factory, the Quatuor is built for exactly that use case. If the goal is a collectible original for the rack, the vintage market still has Four-Voices at vintage prices with vintage maintenance overhead. If you want broad dealer support and a robust second-hand ecosystem, Oberheim's OB-X8 covers that ground. What the Quatuor offers that neither alternative does is a new-build instrument with genuine SEM architecture that won't need a tuning technician before every session.