How to Choose Interconnects and Loudspeaker Cables (TAS 197)

Loudspeaker cables,
How to Choose Interconnects and Loudspeaker Cables (TAS 197)

Excerpted and adapted from The Complete Guide to High-End Audio (Third Edition).
Copyright ©1994–2009 by Robert Harley.

Loudspeaker cables and interconnects are an important but often overlooked part of the playback chain. The right choices of each can bring out the best in your system. Conversely, poor cables and interconnects—or those not suited to your gear—will keep your hi-fi from achieving its full musical potential. Knowing how and which cables to buy ensures the best possible performance at the lowest cost.

How to Choose Cables and Interconects

Ideally, every component in your system—including cables and interconnects—should be absolutely neutral, imposing no sonic signature of its own. Since this is never the case, you’re forced to select cables and interconnects with colorations that counteract the rest of your system’s colorations. For example, if your system is a little on the bright and analytical side, mellow-sounding interconnects and cables can take the edge off the treble and make listening to music more enjoyable. If the bass is overpowering and heavy, lean- and tight-sounding interconnects and cables can firm it up. A system lacking palpability and presence in the midrange may benefit from a forward-sounding cable.

Selecting cables and interconnects for their musical compatibility should be viewed as the finishing touch to your system. A furniture maker who has been using saws, planes, and rasps will complete his work with steel wool or very fine sandpaper. Treat cables and interconnects the same way—as the last tweak to nudge your system in the right direction.

Cables and interconnects won’t correct fundamental component or electrical incompatibilities. For example, if you have a high-output-impedance power amplifier driving current-hungry loudspeakers, the bass will probably be soft and the dynamics constricted. Loudspeaker cables won’t fix this problem. While you might be able to slightly tighten up your soft bass with the right cable, it’s far better to correct the problem at the source—a better amplifier/loudspeaker match. Remember, a cable or interconnect can’t effect an absolute improvement in the sound. The good ones merely do less harm; they won’t make a poor system or bad component-match sound great. Start with a high-quality, well-chosen system and select cables and interconnects that allow that system to achieve its highest musical performance

A typical hi-fi system will need one pair of loudspeaker cables (two pairs for bi-wiring), one long pair of interconnects between the preamplifier and power amplifier, and several short interconnect pairs for connections between source components (such as a turntable or CD player) and the preamplifier. (Systems based on an integrated amplifier obviously don’t need the long interconnect between a preamplifier and power amp.)

Once you’ve got a feel for how your system is—or will be—configured, make a list of the interconnects and cables you’ll need, and their lengths. Keep all lengths as short as possible, but allow some flexibility for moving loudspeakers, putting your preamp in a different space in the rack, or other possible changes in positioning. Although you want to keep the cables and interconnects short for the best sound, there’s nothing worse than having interconnects that are 6" too short. After you’ve found the minimum length, add half a meter for flexibility.

Interconnects are often made in standard lengths of 1, 1.5, and 2 meters. These are long enough for source-to-preamplifier connections, but too short for many preamplifier-to-power-amplifier runs. Such long runs are usually custom-made to a specific length. Similarly, loudspeaker cables are typically supplied in 8' or 10' pairs, but custom lengths are readily available. It’s best to have the cable manufacturer terminate the cables (put the spade lugs or banana plugs on loudspeaker cables, and RCA or XLR plugs on interconnects) rather than trying to do this yourself.

Concentrate your cable budget on those cables that matter. Priority should be given to the sources you listen to most often. For example, you may not care as much about the sound of your tuner as you do about your CD player. Consequently, you should spend more on interconnects between the CD player and preamplifier than between the tuner and preamp. And because all your sources are connected to the power amplifier, this link must be given a high priority. But understand that any component—even a tuner—will benefit from good interconnects.

Most dealers will let you take home several cables at once to try in your system. Take advantage of these offers. Some mail-order companies will also send you a variety of cables to try out: You keep the ones you want—if any—and return the others. Be sure to compare inexpensive cables with expensive ones; sometimes manufacturers have superb cables that sell for a fraction of the price of their top-of-the-line products.

If you’re starting a system from scratch, selecting cables is more difficult than replacing one length in a pre-existing system. Because different combinations of cables will produce different results, the possibilities are greatly increased. Moreover, you don’t have a baseline reference against which to judge how good or bad a cable choice is. In this situation, the best way of getting the ideal cables for your system is to rely on your dealer’s advice. Try the cables and interconnects he suggests, along with two other brands or models for comparison.

Cable and Interconnect Construction

Cables and interconnects are composed of three main elements: the signal conductors, the dielectric, and the terminations. The conductors carry the audio signal; the dielectric is an insulating material between and around the conductors; and the terminations provide connection to audio equipment. These elements are formed into a physical structure called the cable’s geometry. Each of these elements—particularly geometry—can affect the cable’s sonic characteristics.

Conductors are usually made of high-purity copper wire. So-called “six-nines” copper is 99.9999% pure. Some cables and interconnects use silver-plated copper, or even pure-silver conductors. The latter are extremely expensive and have a characteristic sound.

The dielectric is the material surrounding the conductors, and is what gives cables and interconnects some of their bulk. Dielectric material has a large effect on a cable’s sound; comparisons of identical conductors and geometry fitted with different dielectric materials demonstrate the dielectric’s importance. Dielectric materials found in today’s high-end cables include PVC, polyethylene, polypropylene, or even Teflon in the most expensive cables.

The terminations at the ends of cables and interconnects are part of the transmission path. High-quality terminations are essential to a good-sounding cable. We want a large surface contact between the cable’s plug and the component’s jack, and high contact pressure between them. RCA plugs will sometimes have a slit in the center pin to improve contact with the jack. Some RCA plugs have a locking mechanism that allows you to tighten the plug around the jack.

How all of these elements are arranged constitutes the cable’s geometry. Some designers maintain that geometry is the most important factor in cable design—even more important than the conductor material and type. Geometry affects the magnetic interaction between the individual strands of wire, among other factors. Cable designers balance all these factors—conductor material, dielectric, and geometry—in an attempt to get the best-sound possible.

How Much Should You Spend on Cables and Interconnects?

At the top end of the scale, cable and interconnect pricing sometimes bears little relationship to the cost of designing and manufacturing the product. A few manufacturers have marketed good, but not state-of-the-art, cables as ultra-premium products to increase their profit margins. Simply put, many ultra-expensive cables are grossly overpriced.

Some mega-priced cable is, however, worth the high cost of admission, particularly in a state-of-the-art system. It makes little sense to invest six figures in an audio system and compromise it with anything less than the best cables and interconnects. In the legitimately high-priced cable, you’re paying not just for the parts and labor cost to make the cable, but for the intellectual property garnered from decades of research into cable design.

Often, that knowledge trickles down into the company’s lower-priced offerings. The company prices its top-line products for those who want cost-no-object performance, but relies on its mid-priced and entry-level cables for the bulk of its sales. When shopping for loudspeaker cables and interconnects, listen to a manufacturer’s lower line in your system—even if you have a large cable budget. You may be pleasantly surprised.

Because every system is different, it’s impossible to be specific about what percentage of your overall system investment you should spend on cables and interconnects. Spending 5% of your system’s cost on cables and interconnects would be an absolute minimum, with about 20% a maximum. If you choose the right cables and interconnects, they can be an excellent value. But poor cables on good components will give you poor sound and are false economy.

Again, I must stress that high cost doesn't guarantee that the cable is good or that it will work well in your system. Don't automatically assume that an expensive cable is better than a low-priced one. Listen at a wide variety of price levels and to a wide variety of brands. Your efforts will be rewarded with exactly the right cable for your system at  a reasonable price.