Will Microphone Cable work for DMX?
It might. For short runs with a minimal amount of fixtures you probably will not have any problem using regular XLRs, though we definitely advise against this!
Why you should use DMX Cables
Your typical XLR cable has an impedance of 80 ohms compared to a DMX cable’s 120. Impedance is the effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance. So you may find your fixture strobing, and flickering or at a complete loss of signal if you use XLRs.
5pin vs 3pin
By definition of the organization that created DMX, DMX Cable should never be 3 pin, but that hasn’t stopped most of the lighting industry from exclusively using 3 pin. This is because only three pins are actually used for data with two extra pins being included in foresight of future expansion and to differentiate from XLRs. So there is absolutely nothing wrong with using 3pin DMX.
You have invested a considerable amount in your lighting fixtures, so invest in cables you can rely on.