Eurorack Case article
A Guide to Eurorack Case
A eurorack case is the physical housing and power infrastructure that makes a modular synthesiser work. Every Eurorack module needs power — typically ±12V and 5V DC — and a place to mount and connect. The case provides both: a rigid frame with rails for module installation, a power supply, and bus boards that distribute power to each module via ribbon cables. Without it, the modules are individual circuit boards with no way to function together.
How the Power System Works
The power supply inside a eurorack case typically outputs three voltages: +12V, -12V and +5V. Each rail has a maximum current rating in milliamps (mA). Individual modules draw current from these rails, and the combined draw of all your modules must not exceed the supply's ratings. Most builds focus primarily on the ±12V rails since most analogue modules use those voltages; digital modules often require significant +5V current as well. Checking power consumption before buying modules is essential — going over a rail's capacity causes instability, noise and potential damage.
Width and Height
Modules are measured in HP (horizontal pitch), where 1HP equals approximately 5.08mm. Standard widths for cases run from small 42HP skiffs to 2×84HP or larger setups. The height is measured in U: most modules are 3U, which is the Eurorack standard. Cases can have one, two or more rows of 3U rails. A single 84HP row provides enough space for a useful starter system; two rows of 84HP gives genuine flexibility for a more developed build.
Skiffs vs Deeper Cases
A skiff is a shallow case — typically less than 40mm deep — which limits the modules you can use to shallow designs. Most small, portable Eurorack cases are skiffs. Deeper cases accommodate modules with large components or deep connectors. If you plan to use filter modules with long knob shafts, reverb processors with large chips or any module specifically noted as deep, verify the case depth before buying. Standard depths of 60–80mm accommodate almost all current modules.
Powered vs Unpowered
Some cases are sold without a power supply — unpowered or "naked" — requiring you to add your own. This gives flexibility to choose a higher-quality supply but adds cost and complexity. Most beginners should buy a powered case: one that includes the supply as a complete unit. Quality varies considerably at entry level. A weak or noisy supply introduces hum and interference across the whole system, so it is worth paying for a reputable unit rather than choosing purely on price.
Size and Planning
The most common mistake new builders make is buying too small. A 42HP or 60HP case seems adequate when you have four or five modules but fills quickly. The conventional advice is to buy more space than you currently need, because the cost of adding a second case later is higher than choosing a larger one initially. The buyer's guide covers the main models and what to prioritise when choosing. The beginner's guide provides practical setup advice.
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