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Is It balanced? Or Unbalanced?

While it is often overlooked, understanding the difference between a balanced signal path and and an unbalanced signal path is extremely important in setting up a church sound system.

The Long Run

Here’s why: the longer a cable run is, the greater the chance that it will be exposed to interference. A long cable (over 12 feet) is basically just a long radio antenna, and will pick up all sorts of miscellaneous transmissions and noise that’s just “in the air.” How do you know if your connectors are balanced or unbalanced? The accompanying video explains it very well.ART_Passive_Direct_Box

Nip it at the input

The only place you should ever see unbalanced cables used is in the 1/4” to 1/4” shorter high impedance cables that commonly run from electronic keyboards and guitars. Even these need to be balanced before you connect them to the snake or the mixer and that requires a Direct Box (or DI). Direct Boxes are available as either passive (unpowered) or active (powered). Inside the box, the high impedance unbalanced 1/4″ input is converted (by a transformer) into an isolated balanced low impedance signal, which will make your mixing board very pleased. And, as Direct Boxes have an internal transformer that isolates noise, they can also help out when you have a component adding a pesky hum from the signal path.

What else?

You can also increase the efficiency, and reduce unwanted noise and interference by moving the power amplifier(s) as close to the loud speakers as possible. Having the amplifier(s) back at the booth and running yards and yards of 2-connector cable to the speaker cabinets is just wrong. Move the amps as close to the speaker cabinets as possible, and then run balanced lines from the mixer to the amplifier.

One of the big pluses to using powered loudspeakers (active) is that the amp is inside the speaker cabinet which is about as close you are going to get it. In addition, powered loudspeakers have balanced inputs so the line you run from the balanced outputs of your mixer is balanced all the way. The result is a reduction (sometimes huge) in the amount of interference and noise in the system.

If you are using unpowered speakers (passive), your amp should have balanced inputs and either balanced 1/4” (Tip-Ring-Sleeve), XLR (cannon) or unbalanced 1/4” (Tip-Sleeve) outputs. However, just because the connector is an XLR doesn’t mean it’s balanced. And just because it’s a 1/4” doesn’t mean it’s unbalanced. When in doubt, take a look inside the connector to see if you have two conductors plus a shield or only one plus a shield.

About the author

Robert Lindquist

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