Audio Science

I thought I’d start out by saying that I’ve been away for over a month, which would be the reason for the complete lack of articles recently, but now that we’re back in action, let’s touch on a subject that’s often confusing to most people.

Professional single-channel audio line cable (as in not speaker cable) comes in two flavors: balanced and unbalanced. Well, normal professional line audio comes in two flavors. It seems that there is always someone taking something that isn’t supposed to work and claiming that it sounds better.

Let’s start with balanced cable. In normal balanced cable there are two conductors, which carry the hot (in-phase) and cold (inverse-phase) audio signal. It’s the same audio signal traveling along two wires, but the cold wire carries an inverted wave phase version of the signal. Now here’s the reason for this: Everything with an electrical charge emanates an electrical field, usually evident as electro-magnetic and radio-frequency fields. These fields can affect any electrically sensitive materials within their reach to a degree. Since audio is a delicately preserved article, and in signal form must pass through electrically conductive metals, any interference caused by outside sources will result in audio degradation. Internal reflection can also cause slight audio degradation.

The shield (earth) around the conductors protects them from radio-frequency (RF) noise to a degree, but in long lengths is not completely effective, as the cable becomes one long antennae, easily picking RF noise. In combating electro-magnetic distortion, as well, the shield is not 100% effective for isolation. Therefore, the two conductors mutually cancel out noise, allowing much longer lengths to be run.

Unbalanced cable is basically for short length use. It may be a guitar cable, a small patch cord for a patchbay, or anything with a length shorter than 30 feet. The reason unbalanced cable is only usable for fairly short distance is for the same reason balanced cable exists - it is simply much more susceptible to outside interference, and therefore has the potential to introduce more distortion.