31-pin bus, ±15 V)
* BME PM10/Axiom (3U × 8HP, RCA/Phono jacks, 31-pin bus, ±15 V)
* The Synton 3000 (3U × 8HP, 4 mm "banana" jacks, ±15 V) was of similar format, but constructed more like a modern Eurorack synth.By the late 1980s, these had all ceased production.

Dieter Döpfer built some Formant modules before producing his own systems. His Voice Modular System from the early