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Church Sound Recording: Balanced & Unbalanced Connections Really Matter

Connecting recordings for optimal quality and avoiding dreaded hum issues

Recordings of worship services can be a blessing in many ways, and quality recordings aren’t that hard to achieve.

That is, if there is a firm understanding of the fundamentals.

Previously, we looked at how to connect a mixing console to a recording device, considering connector types, Y-cables and identifying the right connectors for your specific situation. (Click here to read that article).

But there’s another option: connecting a console’s XLR (three-pin pro audio) connector to a recorder’s RCA or phone jack input.

Note that the XLR output has three terminals, while the RCA input has only two. And a phone jack connector has two or three terminals, depending upon its design.

Let’s sort this out!

ISSUES OF BALANCE
Every audio cable has one or two insulated wires (conductors) surrounded by a fine-wire mesh called a shield. The shield keeps AC power line interference out of the conductors, which otherwise cause hum.

Connectors and cables are called “balanced” or “unbalanced” (Figure 1). A balanced cable (balanced line) has two conductors and a shield; an unbalanced cable has one conductor and a shield.

In a balanced cable, the two conductors carry the signal, which is protected by the shield. In an unbalanced cable, the single conductor and the shield carry the signal, so the signal is not as well protected against hum.

Figure 1: Balanced and unbalanced cables. (click to enlarge)

Technically speaking, a balanced line carries two identical signals in opposite polarity (+ and -) on the two conductors, and the shield is connected to ground (0 volts).

A balanced input senses the difference between the + and – signals. This doubles the signal level and cancels any interference that is equal on both conductors.

Audio equipment also has balanced and unbalanced connectors. If the console’s master output is an XLR connector or a TRS (tip-ring-sleeve) phone jack, it is balanced.

Meanwhile, RCA (phono connector) or TS (tip-sleeve) phone jacks are unbalanced.

Balanced connections have a relatively high signal level called +4 dBu. Unbalanced connections have a relatively low signal level called -10 dBV.

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