Eurorack is the dominant modular format: 3U tall, 3.5 mm jacks, from a Doepfer standard

Eurorack is a modular-synthesizer hardware standard created by Doepfer in the mid-1990s. It fixes the physical and electrical specification: modules are 3U (three rack units) tall and any width measured in HP (horizontal pitch), patch cables and jacks are 3.5 mm, and power is supplied over a bus board using standard rails (+12V, -12V, optionally +5V). After hundreds of manufacturers entered the market — from small DIY builders to Roland, Moog, and Waldorf — Eurorack became the dominant modular standard, with over a thousand available modules, and has held that position for well over a decade. Its dominance stems from relatively low cost compared to older formats (5U Moog/MU, 4U Buchla/Serge, MOTM) and the enormous diversity of modules, which makes it the recommended entry point for beginners. Eurorack modules cannot be directly mixed with other formats without adaptation; the only exception is signal-level patching through converters.

Examples

A typical starter system fits a VCO, VCF, and VCA in a 3U 84HP skiff case, connected by 3.5 mm cables and powered from a bus board. Doepfer’s A-100 (the pioneering system), Roland’s SYSTEM-500 series, and low-cost Behringer clones all share the same rack form factor and power connectors.

Assessment

Name the connector size, height standard, and originating company of the Eurorack format. Given photos of a 3U Eurorack module and a 5U Moog-format module, identify each and explain why they are not directly interchangeable. List two advantages Eurorack has over older modular formats for a beginner.