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DMX vs Audio Cable Question

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Neal

Member
Are there any adverse problems arrising from using DMX cable for audio cable? This is the 3 pin XLR connector. Want to use the cable from microphone to mixer. I believe the DMX cable is 120 ohms impedence and the audio cable is supposed to be 72 ohms impedence. Will the audio be degraded signifigantly? Have not tried it yet, wanted some advise first.
Thanks,
Neal
 

mneary

New Member
Depends on distance, and actual impedance of the microphone and mixer. At short distances it won't matter. What is your quality expectation?
 

Neal

Member
Forgot to mention the distance is 100 ft. It's just picking up audio above stage area for a play, as long as we get something decent, it should be ok.
Is 100 ft. too long?
 

Mikebits

Well-Known Member
The DMX standard is intended to be like a RS-485 multi-drop bus to control theater equipment. I believe these cables are UTP ( Unshielded Twisted pair ) and as such, I do not think they would do well in a noisy audio environment. Lots of hum I would guess.
http://www.electro-tech-online.com/custompdfs/2008/06/DMX-512.pdf
 

Mikebits

Well-Known Member
Also let me add, at a 100ft, I think it will sound like crap, but I have been wrong before.
 

Neal

Member
I just took an end off the connector to see, it looks like 2 conductors, both are shielded individually and shields tied together.
 

Mikebits

Well-Known Member
I hate when I am wrong. I guess you should just try it and see. Or is that listen.
 

Neal

Member
Will be not able to test til tomorrow at facility, however am hopeful it should be ok. I now think the new DMX cables will be ok for audio. However, I believe the old standard single shielded audio cable may be too noisey for DMX controller aplications. Will post results after I can test it out tomorrow night.
 

Sceadwian

Banned
If it's shielded you're probably fine. If you get a lot of 60hz hum try cutting the shield grounds at the mic and keeping them separate. The shields only need to be saftey grounded at the mixer/amp they'll ground out anything the 100ft of wire picks up.
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
Audio cable doesn't have a specific impedance, it's not used as an impedance matched system.

As long as the cable is well screened, the inner cores are twisted, and it's anti-microphonic, then it will be fine.

If, as you say, the cores are individually screened, then it won't be as good at rejecting external noise and interference.
 

Neal

Member
Are there any adverse problems arrising from using DMX cable for audio cable? This is the 3 pin XLR connector. Want to use the cable from microphone to mixer. I believe the DMX cable is 120 ohms impedence and the audio cable is supposed to be 72 ohms impedence. Will the audio be degraded signifigantly? Have not tried it yet, wanted some advise first.
Thanks,
Neal

Update DMX cable worked fine for audio, no hum, good quality
 

Mikebits

Well-Known Member
Oh no, I see a red square coming for me. Don't I feel silly :(
Glad it worked out for you ...
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Oh no, I see a red square coming for me. Don't I feel silly :(
Glad it worked out for you ...
You've obviously not done PA or recording, the low impedance and balancing of the mikes allows long cables with minimum loss. Using high impedance mikes means you can only have short leads, otherwise you get HF loss, due to the impedance of the mike and the capacitance of the cable forming a low-pass filter.
 
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