PROFESSIONAL AUDIO WIRING
You would think it would be easy to connect professional audio equipment together, but unfortunately it’s not. There can be all sorts of issues that come up; usually it is AC line hum in your equipment you have to deal with. This is normally caused by ground loops in the equipment. This effect can be caused by only a very little current and can wind up having a tremendous impact on your sound and sanity. We will try to clear some issues up for you by showing you how to properly wire XLR connectors and what to do in case of hum.
Audio Outputs:
XLR connectors provide a balanced connection that rejects common mode noise for a cleaner audio signal. Make sure your XLR connectors are WIRED CORRECTLY! Some manufacturers make them incorrectly so you may want to check the connectors and
Ground = pin 1, White = Pin 2, Black = Pin 3. Sometimes you will find red instead of white. Both ends of the cable are wired in the same order, per the following diagram.
| FEMALE |
| 2 Conductor Shielded Cable |
| MALE |
| 2 | WHITE | WHITE | 2 | |
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| BLACK |
| BLACK |
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3 |
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| 3 | ||
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| 1 | SHIELD(GND) |
| SHIELD(GND) | 1 |
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Across pins 2 & 3 of the XLR inputs look for +4 dBu (1.228VRMS) as equivalent to 0 dBuV. The audio output can deliver up to a maximum of 21.2V pk/pk, but then you have to scale the level back down with your audio gain to get acceptable sound in your destination equipment.
Solving ground loop hum:
We don’t expect you to come across this, but if you do, here is what you may do.
1.Try running a wire to connect the chassis of your destination equipment to the source equipment AND the R2XL1. If all are grounded well to- gether, it may prevent the ground loop from traveling down the audio ca- bles.
2.Try lifting the shield wire on your XLR cable on the FEMALE end (the one that plugs into your R2XL1). This will eliminate the path of the ground loop.
