Substituting Microphone Cables for DMX Cables

August 27, 2012 by CHAUVET DJ

by Nick Airriess, CHAUVET® DJ product specialist

It is a common perception that microphone cables can be substituted for DMX cables when setting up your lighting gear. They appear similar because they both have three-pin, XLR connections, as well as male and female ends. However, the actual cables, the part transmitting the DMX signal, are designed different and transmit the signal differently. Read on to learn the difference.

Microphone Cables
A microphone cable is a three-pin XLR cable primarily used for speakers and sound. This type of cable has low impedance and can cause data problems if substituted for DMX cables. These problems can be minor and appear in the form of a flickering fixture, or, they can be huge and cause your entire setup to go haywire and totally unresponsive. Microphone cables can sometimes be used in a pinch and should only be used to connect a few fixtures.

DMX Cables
A DMX cable is a shielded, three-pin XLR cable that transmits data signals between lighting fixtures ensuring a solid, consistent signal. These cables have high impedance and are generally thinner so they can easily wrap around tight corners, fit in small spaces and taped inconspicuously to the floor. The shielding on a DMX cable is generally better because it’s transporting data, as opposed to microphone cables, which are transporting audio signals.

The Terminator
If you are using a significant amount of cables and having signal issues, try using a termination plug. Signal issues may be caused by electromagnetic interference, static electricity, discharges, improper cable termination, excessively long cables and poor quality cables. Though not required, a terminator can absorb the extra signals, which are perceived as data, passing through the cable.

Microphone and line level audio cables lack the necessary electrical characteristics needed for DMX512 cabling. The significantly lower impedance and higher capacitance of these cables distort the DMX512 digital waveforms, which in turn, can cause irregular operation or intermittent errors that are difficult to identify and correct. In other words, think of DMX cables as a big pipe which allows data to flow through easily, and a microphone cable as a smaller pipe which slows down the rate at which data is transferred. If you’re going to spend hours programming your fixtures, why take a chance on using a cable that can inhibit your light show? There’s a reason both DMX cables and microphone cables exist — use them appropriately and your clients and light presentation will thank you.

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