XLR vs. RCA cables

M

Mark-P

Well-known member
I am going to record a presentation that will have 2 people with wireless lavs that are being transmitted to a mixer. I am going to run a direct cable from the mixer to my camera.

1. Are XLR cables of higher quality than RCA cables for this purpose, recording speaking voices?

Thanks.
 
It is not a question of cables being of higher quality, RCA cables are unbalanced, XLR connections are balanced (or can/should be).

RCA has just two lines, and is prone to interference, especially with long cable runs.

Balanced XLR has 3 lines, the signal is sent on two lines with their polarities reversed. Those signals are combined at the recieving end with one signal reversed again, which cancels out cable interference. Balanced connection requires that both the sending and the recieving units are balanced (requires some extra elecronics), the cable itself just carries whatever signal is put through it.

So, if your mixer and camera have balanced XLR connections, it would be stupid not to use them. If they are not balanced or only one is, you have no choice but use unbalanced connections, whatever the connectors are.
 
The main issue with long unbalanced cables is high frequency loss, not noise. Noise, if present, can often be dealt with by repositioning the cable, since what's usually happening is that it's acting more or less like an antenna. In most cases the noise is actually caused by the electronics, not the cable. If an unbalanced cable is too long though, HF loss can't be avoided.

Having said that, in my experience a quality Hi-Z cable of as much as 50' can produce acceptable results (btw, Z = impedance: RCA is Hi-Z and XLR is generally Lo-Z). A quality Lo-Z cable on the other hand, can run hundreds of feet with no loss of signal quality, and considerably less suceptibility to RF interference, although they are by no means immune to it. When so affected, the fix is usually the same - move the cable around to "detune" it.

Certainly the first choice whenever possible is to go Lo-Z. But good Hi-Z cables of reasonable length are in no way a guarantee of inferior results.

Know your tools...
 
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If the signal from your camera is line level, and just traveling a few feet, it really makes no difference. If you want to travel lets say 25-50 feet or more, go for the XLR. I think you will find it difficult to score RCA cables in those lengths, and that should be a clue as to how long a run you should attempt :)
 
one thing to keep in mind is if you are stuck with unbalanced/RCA connections in between 2 points of connection wich are more than 15-20' separated then you could get unbalanced audio->CAT5 (RJ45 connection) converters. Essentially, they passivly convert the source signal to a cat5 cable which can typically run over 2000' w/out noticable loss and then convert it back again. They are pretty inexpensive, and a good alt to running long unbalanced runs.
http://www.intelix.com/products/balun_audio.htm
 
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