Eurorack Case article
Eurorack Case for Beginners: A Complete Guide
Setting up a eurorack case for the first time involves more than unpacking and plugging in. Understanding the power system, how modules mount and connect, and what to check before switching on saves both confusion and the real risk of damaging something. What follows covers the basics clearly.
Understand the Power Rails Before You Start
Every module you buy lists its current draw on the ±12V and +5V rails, usually in milliamps (mA). Before installing any module, add up the total current requirements for all your modules on each rail and confirm they do not exceed the power supply's rated output. The supply in your case will have its ratings printed on it or listed in its documentation. Exceeding a rail's capacity does not just trip a breaker — it can cause hum, instability or damage. Checking this first is not optional.
How to Mount Modules
Modules attach to the rails in your rack using M3 screws (typically 6mm thread with a hex or Phillips head). Most cases include screws; some supply rail nuts that slide along the rail to any position. The key principle is never over-tighten. The panel material on many modules is thin aluminium that strips easily. Finger-tight plus a quarter turn is generally sufficient. Before screwing anything in, position all your modules in the available HP to confirm they fit — note that you must account for the physical width of each module exactly, as there is no tolerance for HP miscalculation.
Connecting Power
Once mounted, connect the power ribbon cable from the bus board to the module's power header. The ribbon cable has a red stripe on one edge indicating the -12V conductor. The module's header typically has a marking showing which pin is -12V, usually marked with a triangle, "−12V" label or a notch on the connector. Connecting backwards reverses the power polarity, which can immediately damage the module. Always check this orientation before applying power. If in doubt, check the module's documentation for a diagram.
First Power-On
Before switching the case on for the first time, verify all ribbon cable connections, confirm no module exceeds the power budget and check that no loose hardware is lying across the bus board. Power on without any audio connections first — listen for unusual buzzing or feel any component getting hot immediately. A warm module after a minute or two is normal; a very hot module immediately after power-on indicates a problem. Switch off and investigate before continuing. Start with just one or two modules if possible to isolate issues.
Patching and Signal Flow
Eurorack signals use 3.5mm mono patch cables. The two basic signal types are audio (oscillators, filters, amplifiers) and control voltage (CV) — envelopes, LFOs, sequencers. CV can be patched into audio inputs and vice versa; the distinction is conceptual rather than electrical. The most useful mental model is: oscillators generate sound, filters shape it, VCAs control its volume, and envelopes provide the shape over time. For full context on choosing and buying your rack, the buyer's guide covers the decision in detail, and the overview explains the system's fundamentals.
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