Sound Advice: Living a Balanced Life

Hal Robertson
December 2003

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We should all live a balanced life, right? At least that's what we're told. Eat less salt, consume more fish oil, and don't forget a healthy dose of exercise. We balance work and family, fun and career. Why not balance your audio connections too? It's not that hard to do and the benefits far outweigh any additional bother or cost. Before you buy a year's supply of multi-vitamins and an Ab-Master, take a look at these tips for using balanced audio cables and connections to improve the sound in your videos.

Way back in the early days of electricity and telephone connections, electrical engineers needed to solve a very specific problem. Delicate signals faded too quickly or became unusable over long distances. They came up with a clever solution to this problem: balanced cables. By balancing their wiring, they achieved two very important improvements. First, they were able to control the noise that crept into the signal. Second, they could run the cables for hundreds, even thousands of feet before seriously degrading the signal. Of course, today, we use fiber optics, microwaves and satellites to transmit our phone conversations, but the balanced connection is the foundation of professional audio.

We're sure you've picked up interference on your cell or cordless phone, but imagine how much interference a radio or television engineer deals with sitting under a tower spewing 100,000 watts of energy. It's absolutely critical that they use balanced audio connections to eliminate the sea of noise trying to muscle into their signal path. And since professional audio is an offshoot of the broadcast industry, it was logical for them to use the same cable technology.

Balancing an audio connection requires three separate wires. One wire carries the signal; this is the part you want to keep. A second wire carries a copy of the signal, but it is inverted 180 degrees out of phase with the original signal. The third wire is the ground connection and serves as a zero-signal reference for the other two wires.

There's one more component in a balanced microphone cable - the shield. This is often an aluminum foil wrap surrounding the entire length of the microphone cable. Alternatively, you'll find some cables use a copper braid or individual strands wrapped around the inside wires. Just as the name implies, this shield serves as a first line of defense to minimize the amount of interference that makes it's way into your cables.

Along with the cabling in a balanced signal, there are also several standard balanced connectors. The most common balanced connection is the XLR plug. Found on everything from microphones to mixers, the XLR cable gets its name from the series number assigned to it by an early manufacturer. Now the term is used generically much like Band-Aid, Velcro and Kleenex. From time to time, you'll hear people refer to XLR connections as "cannon" or 3-pin plugs, but they all mean the same thing. One standard place you'll find an XLR is on the bottom of many handheld microphones. This is a standard connector in professional audio circles because of the durability and reliable connection. Available in male and female versions from various manufacturers, all XLR connections work interchangeably and serve as an excellent balanced audio connection.

Another common balanced connector is the 1/4-inch plug. Often called a phone or TRS plug, these connectors are most often used on audio mixers and other signal processing equipment. TRS stands for Tip Ring Sleeve and refers to the three connecting points on the plug. The 1/4-inch phone plug is a leftover from the old days of operator-assisted telephone calls. The operator would answer your call, and then physically plug your call into a jack on a large panel, electrically connecting you to the person you wanted to call. Of course, all of the switching is all handled by computers today, but the 1/4-inch phone plug remains a common balanced audio connector. We're sure you recognize this plug when you see it, but not all plugs of this size and shape are balance.

Virtually all other audio connections are unbalanced. The RCA plug and 1/8-inch mini plug are both unbalanced and there are unbalanced versions of the 1/4-inch phone plug (stereo and mono), but they only have the tip and sleeve connections. If all of this seems confusing, just remember: it takes three wires for a balanced audio connection.

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