Once again, we’ll glean a subject from our very active CAR SOUND & PERFORMANCE 12-VOLT FORUMS. The question has to do with the subject of interconnect cables and if they can make a difference in a system. My emphatic answer is “of course they can,” — and if you want to know how, then read on.

In today’s world, it’s pretty hard to install a system using high-end aftermarket components without interconnects (or RCAs, as some installers call them). A typical system with a head unit, equalizer, electronic crossover, and a couple of amps can have a dozen or more of these types of cables throughout the car. And, like everything else, we have many choices when it comes to interconnects. We have choices based on appearance, color, gold plating of connects, and several other cosmetic variations. We have a range of pricing that spans from almost nothing, to more expensive than what some of our actual components cost. And, then we have a choice of design that incorporates all sorts of interpretations of physics and marketing.

Choosing a speaker can easily be done by a simple listening test. We can choose an amplifier by simply adding up the wattage rating and the number of needed channels. We can choose a CD player based on how it looks in our dash. But selecting a wire? On what basis should we make this choice? With so much to choose from, it’s no wonder that many feel a little overwhelmed when faced with the decision of how to choose interconnects.

Now, without doubt, the first question is always, “Which cables will make my system sound the best?” To that question I’ll have to answer a very positive, “No wire can make your system sound better!” After all, a wire simply allows electrons to pass from one component to the next, and should do nothing in the way of modifying the signal, amplifying the signal, or processing the signal. This is a fact that should be understood as fundamental whenever a system is installed, or money is spent for a system. If a wire could make your system sound better, we would certainly want to use wires that were much longer than we really need so the music could benefit from passing through even more “sound enhancement.” Eventually, someone would come up with the idea of producing components that merely had wires inside so they could be inserted into our systems as “sound enhancing” components.

Now, the physics of why a cable cannot change your music, or improve it, is pretty basic stuff and, for now, I don’t even intend to cover this exhausting issue. The easy-to-understand factors of this subject are understood with complete certainty, and can be researched by anyone that cares to take the time to study the facts. What I do care to cover is based on solid physics and that’s why a poor choice of wire can make your system sound worse. What did I just say? Yes, you read it right. While a wire cannot do anything to make your system sound any better, cables can do all kinds of things to make it sound much worse.

While the cable may not change the music that’s passing through it, that does not mean that the system’s overall performance cannot be hindered by the cable design. The problem lies not with the music signal, but with what the cable can allow to get added to the music. Anyone who has installed even a modest number or car audio systems can attest to the fact that noise is a definite problem in certain combinations of components and cars. In many cases, the components are not at fault and neither is the actual car. But, it’s the combination of the location of the components in the car, and the requisite routing of the signal cables in that car, that can make for a problem.

Unlike a house that’s made of non-conducting, non-magnetic materials, and has wires that both send and return power, a car frame and body actually passes return current from nearly all the electrical accessories. This creates very strong magnetic noise fields that can be easily induced into any cables that are routed inside the car.

The ability of a cable to pass the music signal without picking up additional noise interference is paramount to having a good sounding system. The best sounding system in the world can be ruined by the addition of unwanted noise. Most of the technology to eliminate noise pickup iin cables has been known for decades. Unfortunately, the subject of noise rejection in cables covers so broad a scope that many products have been marketed with the ability to reject noise that’s not really a problem. For many years, it was commonplace to find “shielded” cables used in cars. The only problem is that those shields were designed to reject RF noise, or very high frequencies. Such noises are not what we hear in a car audio system. Using conventional “shielding” in a car audio system is as useful as a medieval suit of armor is against a modern firearm. While the term “suit of armor” may make us feel safe, it’s only a misconception, just like calling a “shield” protection from noise in a car audio system.

So, what’s the answer to a quiet audio system, and what kind of interconnects should I be using? Well, if your system is already built, and you’re fortunate to have it quiet, then your cables are as good as any will ever be. But, if you happen to have that dreaded alternator whine that just never seems to go away, or you don’t want to take a chance on a new untried system, then there is a technology that is certain to be useful for you. The logical choice would be cables that are designed as unshielded twisted pairs, or UTP for short. While that might sound simple, it apparently isn’t. For several years, my partner David Navone has been studying the application of UTP in cars and has written numerous articles on the subject. Yet, in spite of the simple published facts, it appears that the “markineers” (my term for marketing types that think they are engineers) cannot benefit from his research without “improving” on things.

To illustrate, I’ll relate an actual case study. I recently got an e-mail from a reader who also happens to be a very serious IASCA competitor. His car had a barely audible alternator whine when listened to under judging conditions (i.e., sitting still, engine running, with no music playing). While most folks would have never noticed this while driving, you can be sure the judges did. In fact, this competitor placed second at the World Finals in his class, and it was only the deduction for noise that kept him out of first. He felt he had tried everything to get the car quiet. Many people had looked at the car and the shop that did the install had given up. I was asked to look at the car. As could be expected, the car was done very well and used good quality components. Even the interconnects were of the pricey variety. The owner had not changed the wires in his search for noise, as the cables were a “twisted type” manufactured by a highly respected company.

The problem is that while the cables were of a “high end” design, they were not made in such a way that they would be effective against noise. I simply removed them and replaced the wires with a sensible design of UTP, and the car was instantly quiet. Naturally, the owner was both happy and confused. He couldn’t understand how such a reputable company could overlook something that appeared to be so simple. I told him that I was as confused on that issue as he was, and really had no definitive answer.

So, what’s a person to do? If this is a concern of yours, then here is some simple advice for choosing a good quiet cable for a car audio system. First, it should not have a foil or braided shield. While “shields” can be effective in certain applications, the car is not one of them, and, in fact, in a car, shields tend to become “noise antennas.” Second, look at the size of the actual conductors. They should be small, symmetrical, and evenly twisted together. Any insulation that separates the conductors more than is absolutely necessary can cause noise to be induced into the wire. Third, make sure that the wire has no unnecessary conductors or fillers that separate the conductors any more than is absolutely necessary. Anything that’s added to the wire for “looks” is only going to increase the chance of unwanted noise pickup.

And finally, if you’re running two- or four-channel connections to a single amplifier, be sure that all the channels are incorporated into the same cable instead of running separate pairs to the same termination point. By following these simple guidelines, choosing a quiet wire should be easy. To understand more about the why of this subject, check out David Navone’s Forum at www.carsound.com, or look up some of the technical articles he has written on this very timely subject in past issues.