Why using the wrong wiring can compromise your sound system

Why using the wrong wiring can compromise your sound system

In many of the sound systems we are asked to analyze we find that the installer used small, inexpensive wiring to connect the speakers. Why is this important? Wiring has a given resistance per foot. The smaller the wire the greater the resistance per foot. So now the power you were calculating to drive your speakers is being lost before it ever gets to the speakers. The whole circuit becomes a voltage divider of sorts.

Here’s something I’ve seen in at least three churches over the last several months, so I know it happens.

Let’s suppose there’s a standard 100-foot audio snake from the console position running to the stage. But instead of putting the amp rack on the stage, maybe the facility is using a powered mixer at front of house, or the amp rack is already sitting next to the mixer.

A look over at the audio snake shows XLR inputs from the microphones, but there are also two or four TRS 1/4-inch jacks that look just like the 1/4-inch loudspeaker jacks on the back of the powered mixer or amplifiers.

Figure 1 shows a standard Hosa Technology snake with 24-gauge wires for both the XLR mic inputs as well as TRS 1/4-inch returns. Looks like you can plug the TRS fan-out end into the back of a power amp and passive stage monitors into those phone jacks on the stagebox, doesn’t it?

Well, we know this “sort of” works, but there’s a certain amount of wattage loss from the 100 feet of 24-gauge cable instead of 100 feet of 12-gauge cable, which is industry recommended for this sort of loudspeaker run.