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Ground Loops - 4 - Balanced connections

As you can imagine, an unbalanced connection is likely to suffer from induced noise, and this was why the balanced input and output was developed. As you will see in Fig 7, the link between two items of gear is now made using 3 connections, a +ve, -ve and a ground. Only the +ve and -ve connections contribute to the audio, and the cable screen now simply protects these two as in Fig 8. For best drainage of induced currents, this screen connector should be bonded to the chassis of the unit at each end. The balanced input/output provides further noise suppression as any induced currents that do get through to the +ve and -ve connectors can be filtered out as they will be equal in both wires, whereas the audio signal is +ve in one and -ve in the other.

Balanced connections are made using XLR connectors or Stereo Jack Plugs. Figs 9 shows an open Neutrik XLR showing the three soldered connections and Fig 10 shows an XLR to Stereo Jack adaptor lead on the left and an XLR to XLR lead on the right.

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