eurorack

Eurorack is a modular synthesizer format and ecosystem that has become the dominant standard for contemporary modular systems. It was developed by Doepfer Musikelektronik in the mid-1990s and has since evolved into a large, open marketplace with thousands of third-party modules and case options.

The format defines physical and electrical specifications that enable interoperability across brands. Modules are typically 3U tall and widths are measured in HP (horizontal pitch), with 1 HP equal to 5.08 mm. Common modules range from small 8–10 HP units to larger 40–60 HP units. Modules are mounted in a rack or case that shares a common power bus. Eurorack uses power rails, commonly ±12 V, with some modules requiring or using additional +5 V for digital logic. A standard 16-pin flat ribbon cable connects each module to the case’s power bus, providing both power and a common ground.

Interoperability is a key feature of Eurorack. The standardization of form factor and electrical connections allows modules from many manufacturers to be mixed and matched. This has driven a vibrant market that includes both commercial and DIY modules, diverse sound engines, and a wide range of envelopes, filters, oscillators, sequencers, effects, and utility devices. The ecosystem is augmented by a broad base of accessory products, such as power supplies, cases, and cabling.

Signal types in Eurorack centers on analog and digital control voltage (CV) and audio. Common control conventions include 1V/Oct pitch control and gate or trigger signals for envelopes and sequencing, though some modules implement alternative CV standards. The format supports hybrid setups combining analog and digital technologies and remains widely used for experimentation and sound design.