A modular synthesizer format developed by Doepfer in the mid-1990s for its A‑100 system, but which has since become a standard format embraced by most modular synth manufacturers.
It uses 3U high panels to accommodate standard Eurocard-size electronics, with 3.5mm plugs for patching and a +/-12V dual-rail power supply (sometimes with a separate 5V rail) connected via a ribbon cable.
Doepfer A-100 Modular Synth.Photo: Mark Ewing