1 Scope

1.1 Purpose

The Eurorack Interface Specification (EIS) defines the mechanical and electrical interface between Eurorack modules, enclosures, bus boards, power supplies and power converters, and the cables that join them.

A requirement is a shall only where, without it, a conforming product from one maker could fail to fit, power up, or work with a conforming product from another. That covers mechanical fit, power entry and distribution, published supply figures, and declared signal classes. Construction choices that do not change interoperability, such as board material, module depth, rail section, or screw finish, are described and recommended, not required.

1.2 Applicability

EIS applies to six product types (Conformance):

• A module: front panel, board clearance, patch jacks, power entries and header current, the port list with signal classes and the formats of its rear video reference ports, patch safety; a DC entry panel or a reference distributor in module form claims the features of what it carries (5.1, 5.2, 6.1, 6.3, 6.4, 6.6, 6.7, 6.8, 6.9, 7.1, 7.2, 7.3, 7.4, 8.1).
• An enclosure: rack frame, rails, inserts, mounting screws, published row width and depth; what is built in claims its own role: a built-in supply is a power supply, a built-in bus board a bus board; a case DC entry claims PWR-DC12-IN (5.1, 5.2, 5.3, 5.4, 6.1, 6.2, 6.3, 6.5, 6.7, 7.3, 7.4, 8.1).
• A bus board: headers, links, published capacity, one 0 V, row wiring terminals; and whatever else it carries behind the panel: a DC rail, the ±6 V rails, the video reference tree, or the case's CTRL-USB-HOST, each a feature it claims (6.1, 6.3, 6.4, 6.5, 6.7, 7.3, 7.4, 8.1).
• A power supply: rails, output connector, protection, published ratings and ripple, the earth bond of 0 V, row wiring terminals; a supply may also make the 12 V DC rail or the ±6 V rails and claims that domain (6.1, 6.2, 6.3, 6.4, 6.7, 6.8, 6.9, 8.1).
• A power converter: a source for one product that makes one power domain from another, such as ±6 V from the bus on the back of a module (6.1, 6.2, 6.3, 6.4, 6.7, 6.8, 6.9, 8.1).
• A cable: the interface it mates: power ribbon, video, DC, PWR-A6, or CTRL-USB (6.4, 6.5, 6.7, 6.8, 6.9, 7.4, 8.1).

Fourteen optional features, PWR-BUS-IN, PWR-BUS-OUT, PWR-DC12-IN, PWR-DC12-OUT, PWR-A6-IN, PWR-A6-OUT, PWR-A15-IN, PWR-A15-OUT, VID-REF-IN, VID-REF-OUT, VID-REF-PASSTHRU, VID-REF-LOOPTHRU, CTRL-USB-DEV, and CTRL-USB-HOST, add requirements to a product that claims them. Every power domain is a feature a product claims for its entries and outlets, and distributing a rail or the video reference is a capability it claims through those features, not a product type. A product that claims none of them conforms to EIS Core: Part 2 (mechanical), Part 4 (signals and video, patch jacks and video timing only). Chapter 9 binds the person who assembles a system, not a product.

1.3 Exclusions

EIS does not specify:

• product catalogs, mains wiring or earthing, or the safety or EMC certification of a product;
• the internal protocol of digital video or data streams;
• ports other than patch jacks, video reference ports, power entries, and CTRL-USB ports, such as coaxial picture video, line and microphone audio, MIDI, DMX512, word clock, and the ILDA connector; Annex I gives an informative vocabulary for naming them;
• power rails outside the power domains of 6.1;
• a precision control-voltage class beyond MOD-CV-1VOCT pitch tracking; the stability of a DC reference or the accuracy of a quantizer is a product figure;
• factory test procedures (4.3).

1U in EIS is the Intellijel 1U format: a 39.65 mm panel with a 33.65 mm hole span. Pulp Logic 1U tiles, 43.18 mm high, are a different format, physically incompatible with it, and are outside EIS.

1.4 Where the values come from

Every requirement records the origin of its value, its provenance (Terms):

• Quoted from a dated publication. Rack geometry comes from IEC 60297-3-101:2004 and IEC 60297-3-100:2008: the HP, the rack unit, and the frame dimensions a rack-mount enclosure meets (RACK-003). The M3 thread pitch and major diameter come from ISO 261:1998 (RAIL-006, RAIL-007).
• Inherited from the Doepfer A-100 and restated in EIS words: the 3U panel height, the hole inset and drill, the patch jack, the panel width and thickness ceilings, the power header pinout, marking, and keying, the ±12 V and +5 V rails, the gate thresholds, and the bus CV and gate levels, regions, and links. The 1U panel height is inherited from the Intellijel 1U format.
• Set by EIS: the M3 mounting screw and its length window, board edge clearance, the published width, depth, and current of a module, the power header form and its current limit, the signal classes and their ranges, patch safety, the video class MOD-VIDEO, the 0 V reference and its earth bond, bus-board capacity, supply protection, published ripple and the ripple floor, rail and enclosure geometry, and the features of 4.1.

The patch levels are EIS figures, not inherited ones. Doepfer publishes typical ranges (audio 10 Vpp, LFOs ±2.5 V, envelopes 0 to +8 V) and no impedance. EIS sets audio and control CV at ±10 V peak because modules in use exceed those ranges and an input has to accept what an output may send (Annex E).

Where EIS states a value, that value governs a conformance claim. The tests compare EIS with the published A-100 figures and report where they differ.