Can you use a mic cable to run a DMX signal? The short, and only correct answer is “no”.

May 3, 2017 by Ben Stowe, CTS

Can you use a mic cable to run a DMX signal? The short, and only correct answer is “no”.

Here are the physics. A DMX signal is a digital signal comprised of 1s and 0s being transmitted at a rate of roughly 250,000 per second. Each piece of binary data must remain legible to the receiving end, or the data is no longer useful. 1s must remain 1s and 0s must remain 0s, and they must arrive with the correct timing. Thus, a cable is designed with the electrical characteristics ideal for this type of signal (capacitance and impedance most notably) and it then must be properly protected with appropriate shielding.

This does not mean that a DMX cable is superior and should then be used for both DMX and analog audio. Here again, analog audio cables are designed with the best set of electrical characteristics for that type of signal. High quality analog audio cables usually have larger conductors too.

Beyond that, all cables are not created equal. There is definitely no free lunch. Unfortunately, price isn’t always a good indicator either. A cheap cable can safely be written off as cheap. But taking a cheap cable and charging a lot more for it doesn’t make it a better cable. Look at the specs. As long as the specs are from a meaningful source, they can be a valuable tool. Be wary of things that look too good to be true of course, and if they don’t have specs… I would simply move on to the next cable. Why buy something when you don’t know what you’re buying??

Here are some example specs from NLFX Professional Platinum Series cables. You can clearly see the different electrical characteristics:

For Platinum Series DMX Cable:

  • 22 AWG 19 strand Annealed Tinned Copper
  • DC Resistant -14.7 Ω / Mft @ 20º C
  • Impedance – 110 Ω / Mft +/- 10%
  • Capacitance – 12.00 pF / ft +/- 10%
  • Aluminum Mylar shield – 100% coverage
  • Tinned Copper Braided shield – 85% coverage

For Platinum Series Mic Cable:

  • 20 AWG – 26 strand Annealed Tinned Copper Conductors
  • DC Resistant -10.6 Ω / Mft @ 20º C
  • Impedance – 72 Ω / Mft +/- 10%
  • Capacitance – 21.2 pF / ft
  • Cable drain 19 strands Tinned Copper
  • Tinned Copper Braid – 95% coverage

Now let’s post some pictures of a few different types of cables. Note that the cheap, spirally shielded mic cable has tiny conductors, virtually no shield and that the shield must be twisted into the ground conductor. By contrast, the Platinum Series mic cable has 20 gauge, robust twisted conductors, a tight, thick braid, and a separate ground conductor within it. Then take notice of how different the DMX cable is from either. Most often, when people use a cheap mic cable for DMX they are doing so because it is cheap. Then we end up with a cable that is not only inferior for it’s intended purpose of transmitting analog audio, but also woefully inadequate for the purpose of transmitting a digital signal that it was never intended to be used for.

Spirally shielded inexpensive mic cable

Braid shielded quality mic cable

Braid / Foil shielded DMX cable

Ben Stowe, CTS Ben Stowe, CTS (10 Posts)

Ben’s love of electronics and technology led to years of schooling in Electricity, Electronics, Robotics and Lasers. Ben supported himself through school by building and selling strobe lights and other electronic devices. He built his first DJ show largely from scratch and scrap, often repairing broken items others had thrown away because he could not afford to buy new equipment. He holds a Minnesota electrical license, and his AV installs have been featured in almost every major industry trade magazine. His relentless passion for education has led to a number of other certifications and accreditations, including the most widely recognized one in the AV industry, the InfoComm CTS. His love for education inspired him to begin the ProAcademy educational sessions, focused on increasing understanding of AV technologies within the industry. Ben has been involved in a number of technical writings, lectures, presentations, as well as research and development assistance with a number of manufacturers for products, industry wide. He is also a regular contributing author to industry magazines in the United States and Europe. Ben’s presentations have been featured across the world both as a part of industry leading trade shows, and as a presenter for various groups and functions. Some of these events include BPM in the United Kingdom, Mobile Beat, the ADJA National Convention, Wedding MBA, and a national tour as a headlining presenter for an industry magazine. The United States Armed Forces branches have also called upon Ben to provide engineering and training assistance. His highly informational, slightly nerdy and always funny presentation style have made him a favorite at events, while his sincere desire to help people with their application of technology have made him a favorite with them after the event. Ben serves the industry as the President of NLFX Professional, an industry leading supplier of sound, lighting and video systems, a role he has maintained since founding the company in 1993.

Filed Under: Lighting, Sound