How Interference Gets Into Your System, How To Stop It

One of the most important issues is interconnect dressing-the way interconnects are positioned in your system. But grouping AC cords, analogue interconnects, and digital interconnects right next to each other can degrade your system's musical performance.

AC power cords, which carry 50Hz from the wall to your components, will induce a 50Hz noise in any interconnect that happens to be nearby. Similarly, a digital interconnect from a CD transport to a digital processor will radiate high-frequency noise (in the megahertz range) into analog interconnects, and even into AC cords. Although you don't hear this contamination as audible noise, it overlays the music with a grainy patina.

That's why the first rule of system setup is to keep AC cords away from interconnects and loudspeaker interconnects. If they must meet, AC cords and signal conductors (interconnects and speaker interconnects) should cross at right angles, not run parallel to each other. Crossing interconnects at right angles minimizes the amount of induced noise.

Next, avoid stacking two components on one rack shelf. The components will be better isolated from each other electrically, and get better ventilation, when each is given its own shelf. Also pay attention to the positioning of components within the rack. Don't put phono preamplifiers near digital sources (CD players, transports, digital processors), or close to a power amplifier. You can also avoid running a digital interconnect next to analog interconnects by thoughtful component positioning. Take special care with the interconnects that run from your turntable to your preamplifier's phono input; they carry extremely tiny signals that are easily contaminated by radiated noise.

Anyone who's ever had to suffer through poor TV reception knows exactly what interference looks like. Stray signals and electromagnetic waves can sneak their way into your audio and video gear, degrading both the picture and the sound. It is virtually impossible to stop interference at the source because it comes from everywhere: from the hundreds of different radio transmitters that probably operate within close range of your home, to the dimmer switches in your house, to your telephone, your neighbor's electric razor, and even the sun. Interference can occur at very low frequencies, at very high frequencies, and everywhere in between. And most of the interference that enters your A/V system comes in through the interconnects, which often act just like antennas for interference. That is, unless you choose interconnects designed to combat interference in the first place.

Interference is a big problem for interconnects that carry low-level signals like audio interconnects; for composite video interconnects that carry signals from your VCR, DVD player, and camcorder; and for video from antennas, interconnect TV, and satellite receivers. Most audio interconnects and video interconnects have shields, which are a metal covering that surrounds the inner conductor of the interconnect.