DMX Cable & Termination Field Guide

“DMX cables go bad” is still a top issue in your report (e.g., low CTR on timing, cables). This guide explains why the physical layer is so critical.

DMX cable vs mic cable

• DMX cable: 120 Ω characteristic impedance, tight twisted pairs, shielding built for differential signals.
• Mic cable: ~50 Ω, loose twists—works in a pinch, but reflections and jitter spike after 30–100 m.

Length & termination rules

• Official spec allows 300 m, but industry best practice uses 100–150 m for reliability.
• Terminate the last fixture with a 120 Ω resistor; every branch must flow to a term.
• Avoid Y-splitter, daisy-chain every fixture sequentially.

Connectors & splitters

• Use 5-pin DMX connectors unless a fixed installation uses 3-pin (with documentation).
• Optical splitters solve grounding/loop issues—refer to DMX Splitters & Opto-Isolation.

Testing & validation

• Swap cables one section at a time to isolate jitter.
• Use the DMX Addressing Chart to verify patch correctness in parallel with the cable run.

Actionable checklist

• Use DMX-rated cable; label each run.
• Terminate the last fixture in every backbone.
• Avoid passive splits; prefer active, opto-isolated distributors.
• Test with the DMX timing checklist and document results.