Part 13: Getting the Best Sound from Cables and Interconnects

One of the most important issues is cable dressing-the way cables are positioned in your system. In an attempt to make their systems look tidy, some audiophiles bundle all the cables together with tie-wraps. But grouping AC cords, interconnects, and digital cables right next to each other can degrade your system's musical performance.

To understand why, consider how a moving-magnet phono cartridge works. The tiny magnets, suspended between coils of wire, are moved back and forth by the modulations in the record groove. The relative motion between the magnetic field and the coils induces (creates) electrical current flow through the coils. When this electrical current flow is amplified and converted into sound by the loudspeakers, we hear it as music.

The same sort of magnetic field around a cable in your rack can induce an unwanted signal in an adjacent cable. Audio signals flowing through a conductor create a magnetic field around that conductor. This magnetic field expands and collapses around the conductor at the same frequency as the audio signal. The magnetic field's expansion and collapse provide the relative motion between the magnetic field and a nearby conductor, inducing an electrical signal in any conductor within that field. This means that AC power cords, which carry 60Hz from the wall to your components, will induce a 60Hz noise in any cable 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 cables. If they must meet, AC cords and signal conductors (interconnects and speaker cables) should cross at right angles, not run parallel to each other. Crossing cables at right angles minimizes the amount of induced noise.

A simple trick for further reducing interaction between cables is to place 1"-square blocks of Styrofoam between AC cords, interconnects, or speaker cables where they cross. Use the blocks at every cable junction to separate interconnects, speaker cables, and AC cords from each other.

Putting Styrofoam blocks between interconnects at the back of your rack is more of a challenge than laying out cables on the floor. A little glue on the interconnect or power cord will hold the lightweight Styrofoam, provided you're not constantly moving interconnects. Rubber bands can also hold the blocks in place.

Even a small physical separation has a large effect. The "inverse square law" states that the strength of a magnetic field diminishes in proportion to the square of the distance. Consequently, you don't need large distances between cables to isolate them from one another-that's why the 1" Styrofoam blocks are so effective.

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.

Here are several other tricks to help you keep interconnects and cables from degrading your system's sound:

1. Because all wire degrades the signal passing through it, the less wire you have in your system, the better. Keep interconnects and loudspeaker cables short.
2. Keep left and right loudspeaker cables, and left and right interconnects, the same length.
3. If you have excess cable or interconnect, don't wind it into a neat loop behind the loudspeaker or equipment rack. This will make the cable more inductive and change its characteristics. Instead, drape the cable so it crosses other loops at right angles.
4. Periodically disconnect all interconnects and loudspeaker cables for cleaning. Oxide builds up on jacks and plugs, interfering with the electrical transfer. Use a contact cleaner (available at most high-end stores). It works. In fact, switching interconnects sometimes cleans the jacks, making the system sound better even though the interconnect may not be intrinsically better.
5. When connecting and disconnecting RCA plugs, always grip the plug, never the cable. Remember to push the tab when disconnecting XLR plugs.
6. Ensure tight connection of all RCA plugs, and particularly spade lugs on power amplifiers and loudspeakers. Get lots of contact surface area between the spade lug and post, then tighten down the binding posts.
7. Avoid sharp bends in cables and interconnects.

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