Miltone’s 4Exp expands the Oberheim FVS-1 to eight voices

Miltone’s 4Exp was unveiled at Superbooth 2026 and opened for pre-order in a first batch of 50 units. The four-voice expansion module promised to turn an original Four Voice into an eight-voice instrument.

Oberheim introduced the SEM in 1974 as a keyboard-less Synthesizer Expander Module with two VCOs, a 2-pole multimode filter, ADR envelopes and an LFO, then paired SEMs with keyboards for the Two Voice and Four Voice at the June 1975 NAMM Show. Tom Oberheim’s historical product page calls the Four Voice the first commercially available polyphonic synthesizer, while reference sources place the Four Voice in 1975 and the Eight Voice in 1977. An optional Polyphonic Synthesizer Programmer followed in 1976, storing and recalling up to 16 instances of some SEM parameters.

Miltone, the Paris-based repair company operating under the Vintage Synths & Co name, built the 4Exp around that same collector logic. As a standalone unit, it functions as four independent monophonic dual-VCO voices. Paired with an original FVS-1, it becomes an eight-voice system. The company is offering beige or black modules with either Aluminum or Tolex chassis options, and the instrument is hand-crafted in Paris and individually numbered. CV/Gate control is available now, while MIDI is still under development.

The Aluminum version costs €9,990 ex VAT and the Tolex edition costs €11,990 ex VAT. A refundable €1,500 reservation deposit secures a place in the queue, and first deliveries are expected from late 2026 onward.