live-coding-academy_ ⌕ search
home/ atoms/ eurorack-power-budgeting

A Eurorack case's power supply must cover the summed current of every module across the +12V/-12V/+5V rails, with headroom

Fact L2First instrument E · Modular, Eurorack, grooveboxes & dawless

Each module draws current from the case’s power supply, distributed over ribbon cables across +12V, -12V, and sometimes +5V rails. Before assembling a system you must sum every module’s current draw on each rail and confirm the supply’s capacity exceeds it, leaving 20-30% headroom — running near the limit causes instability and malfunctions. Rails are independent: a module can be fine on +12V but exceed the -12V budget. If a module needs +5V and the case lacks that rail, a +5V adapter (derived from +12V) can supply it. Power budgeting is done per-rail, not as a single total.

Examples

A case with a 1A (+12V) supply and five modules drawing 200mA each on +12V = 1000mA = exactly the limit. Adding a sixth risks instability; aim to stay under ~700-800mA to keep 20-30% headroom.

Assessment

Given a case supplying 1.5A on +12V, calculate the maximum safe +12V draw with 25% headroom. A module needs +5V but your case has no +5V rail — what is your option?

Prerequisites — understand these first

Don't confuse with

Sources

“Each module draws power from the case’s supply, typically across +12V, -12V, and sometimes +5V rails. It’s vital to calculate total power usage and ensure the supply has adequate capacity with some headroom (20–30%).”
corpus · modular-synthesis-101-a-guide-to-eurorack-modular-ali-jamies · chunk 3

Taught in modules

Unlocks (1) — atoms that build on this