DMX 電纜與麥克風電纜：主要差異

8 月 12, 2026

Introduction

Walk into any stage tech store and you will see two cables that look almost identical: the DMX cable for lighting control and the microphone cable for audio. Many buyers assume they are interchangeable — and that assumption causes intermittent flicker, signal dropouts and failed shows.

This guide explains the engineering differences between DMX and microphone cables, when you can (and cannot) swap them, and how to spec the right cable for stage, rental and fixed AV installations.

The Short Answer

DMX512 cable is a 2-core shielded cable with a characteristic impedance of 120Ω and conductors around 0.5–0.75 mm².
Microphone cable is a balanced 2-core shielded cable with low capacitance, typically 50–75 pF/m, designed to preserve weak audio signals over distance.
The two are not interchangeable in critical applications: using mic cable for long DMX runs can cause flickering; using DMX cable for microphones can reduce high-frequency response.

Impedance: The Critical Difference

DMX512 (USITT standard) expects a cable with 120Ω characteristic impedance. The data signal is a differential pair running at 250 kbit/s — at that speed, cable impedance mismatch creates reflections that distort the signal waveform. On long runs, reflections show up as fixture flicker or total data loss.

Microphone cable, by contrast, is specified for low capacitance rather than characteristic impedance. The audio signal is an analog waveform measured in millivolts; the main enemy is capacitance, which rolls off high frequencies on long runs.

Property	DMX512 Cable	Microphone Cable
Impedance	120Ω characteristic	Not impedance-critical
Core size	0.5–0.75 mm² (typical)	0.5–0.75 mm² (typical)
Capacitance	Moderate	Low (50–75 pF/m target)
Shielding	Braid + foil (good)	Braid or foil
Best use	Lighting data, fixtures	Mics, line-level audio

The Connector: 5-Pin XLR for DMX, 3-Pin XLR for Microphone

Buyers usually search “dmx 5 pins” or “XLR 3 pins” rather than the cable word, because the connector is the first thing you see on a rig. The pin count is part of the product difference, not a house convention:

Connector	Where it is the standard	What each pin carries
5-pin XLR	DMX512 / DMX512-A lighting control (ANSI E1.11, E1.27-1)	Pin 1 shield / common, pin 2 data 1−, pin 3 data 1+; pins 4 and 5 are the optional second data link and stay unused on most fixtures
3-pin XLR	Balanced microphone and line-level audio	Pin 1 shield, pin 2 hot (+), pin 3 cold (−)
3-pin XLR on lighting fixtures	Widespread on budget fixtures and small controllers, but it is not the connector the DMX512 standard specifies	Same two data lines plus shield, so adaptor leads between 3-pin and 5-pin are normal rental stock

Two consequences when specifying: a finished 3-pin microphone lead cannot become a 5-pin DMX lead without an adaptor, and no adaptor fixes the cable behind the connector — it still has to be the 120 Ω construction described above. The pin-by-pin detail for 4-, 5-, 6- and 7-pin connectors is in XLR pin counts explained; the one-pair versus two-pair question is in stage DMX cable: 1-pair vs 2-pair; and what to fit on the last fixture is in DMX termination.

Shielding and Construction

Both cable types are shielded, but the priorities differ:

DMX cable needs reliable shielding against interference from nearby dimmer packs and power cables. A combination of foil + braid shielding is common on professional DMX cable.
Microphone cable needs flexibility and low handling noise. PVC jacket with a fine-stranded conductor and braided shield keeps the cable quiet when coiled and uncoiled on stage.

LBS manufactures both families: the LBSDMX series covers DMX512 lighting control cable and multichannel snake cable, while the same factory line produces shielded constructions suitable for stage signal routing.

One substitution is asked about more often than either of these two cables: putting the DMX signal on a network pair. Cat5e and Cat6 are specified at a different characteristic impedance from the 120 Ω bus, so that is a physical-layer change rather than a cable swap — the two cases are separated in DMX over Cat6: can you run DMX512 on Ethernet cable?

When Can You Swap Them?

Short runs (under 15 m), temporary setups: many rental crews use good-quality microphone cable for DMX on short links. It usually works — because reflections have less distance to build up.

Long or permanent runs: do not substitute. For fixed installs, termination practice (120Ω terminator on the last fixture) matters as much as cable type.

Microphone use of DMX cable: generally works for short mic leads, but the higher capacitance of a DMX-spec cable can dull high frequencies on runs over 10–15 m. For vocal mics and line-level signals, use a dedicated low-capacitance microphone cable.

What LBS Publishes for This 2-Core Shielded Construction

Both LBS DMX512 families are 2-core (one pair) plus shield, 6.3 mm nominal jacket O.D., rated −20 °C to +70 °C. The real choice is the shield level, and it is published per family rather than left to the data sheet of a single size:

Published item	Single-shielded (LBSDMX…-1)	Double-shielded (LBSDMX…-2)
Conductors	2	2
Shield build	High-density OFC spiral, 85%+ coverage	100% coverage AL-foil + heavy-duty tinned-copper braid / spiral
Jacket O.D.	6.3 mm	6.3 mm
Jacket	EPVC matte	EPVC matte
Applicable temperature	−20 °C to +70 °C	−20 °C to +70 °C
Characteristic impedance	not stated on the product sheet	120 Ω

Strand counts and conductor sizes differ per model within each family (128/2×0.35 and 144/2×0.50 are both in the range), and each product page carries its own sheet: LBSDMX128035 single-shielded and LBSDMX128035-2 double-shielded. Which shield level belongs on which run is a separate decision.

Specifying for Your Project

Ask three questions before ordering:

Signal type — DMX lighting data or analog audio? This decides the impedance and capacitance spec.
Run length — over 15–20 m, buy the dedicated cable type.
Environment — stage floor, truss, permanent conduit? This decides jacket and flexibility requirements.

For rental fleets and installers buying in volume, LBS supports OEM/ODM orders: custom lengths, printed brand/model on the jacket, custom colours and packaging (reels, drums, boxes). See the OEM page for the factory standard process.

Related Products

LBS builds both shield levels of this construction. If your project needs the foil-plus-braid build for a noisy environment, it is listed separately as the double-shielded LBSDMX144050-2 DMX512 lighting control cable, alongside the single-shielded LBSDMX144050.

FAQ

Can I use microphone cable for DMX lighting?

For short temporary runs (under 15 m) it often works, but DMX512 is specified for 120Ω cable. For long or permanent runs, use a dedicated DMX cable and terminate the last fixture with a 120Ω terminator to prevent signal reflections.

What is the maximum DMX run length?

The DMX512 standard recommends a maximum of 100 m (about 300 ft) per universe run between controller and last fixture. Using correct 120Ω cable and proper termination gives the most reliable results.

What gauge microphone cable do I need for a stage?

For standard balanced microphone runs up to about 50 m, 2-core cable with 0.5–0.75 mm² conductors and a good braided shield is the industry norm. LBS manufactures this construction in the LBSDMX series with multiple channel-count options.

Does cable length affect microphone sound quality?

Yes — longer mic cable adds capacitance, which rolls off high frequencies. Low-capacitance microphone cable minimises this. Beyond roughly 50–60 m, consider a direct box or digital stage box instead of a very long analog run.

Is DMX 5-pin or 3-pin?

DMX512 is specified on 5-pin XLR connectors. Many budget fixtures and controllers ship with 3-pin XLR instead, and adaptor leads are normal rental stock, but 3-pin is not the connector the standard defines. Either way the cable behind the connector should be 120 Ω DMX cable, not microphone cable.

Is DMX cable the same as a “3 conductor” cable?

No. DMX512 cable is one pair (2-core) plus shield. “Three conductor” is the naming used for balanced microphone cable, where the two cores and the shield are counted together — the same physical cable can be described as 2-core shielded or 3-conductor depending on which naming system the buyer uses. The counting rules are in cable cores vs pairs vs conductors.