At one time or another, each of these specs was devised for a reason, and there's no doubt that all of these numerous terms have importance. Each of them was coined to describe a characteristic or the value of a measurement. Many times, however, these specs get used in a way that distorts their real importance. The problem is in their original purpose and their use beyond that purpose. In this issue, David Navone is doing an article on tuner specs. As David explains, the performance of a tuner is very hard to quantify with simple numbers. The variables in use for a mobile tuner are so infinite that nailing performance down with a few numbers is next to impossible. This is especially true when it's understood how the measurements are made and how they represent the real world.

The tuner spec problem is really a matter of there being a problem with the measurement duplicating actual listening conditions. Because duplication of this exact condition is not possible, the spec can never be considered more than a general guideline. However, this is not the only problem with specs. Some specs suffer from other shortcomings. For example, some specs are very easy to quantify, but their real importance is overstated. Distortion, for example, is a very important spec. It can tell us about how well a component is designed. Over the years, components have gotten so good that the distortion spec has far removed itself from real perception.

Today, numbers on the order of .00 are common. Multiple digit decimal places for a spec where it is difficult to hear below 2 or 3 percent distortion seem a little out of order. Typical components today have distortion levels that are one hundred to one thousand times less than we can hear. While many audio enthusiasts can quote the distortion specs of their favorite equipment, very few have any idea of their hearing threshold for distortion.

Another category of a misguided spec is the type that has little value for technical reasons. A spec of this nature is typified by that old term damping factor. On our Car Sound Forum this month, there were several questions about this spec. It's one of those unimportant things that are so easy to explain; yet, it somehow always surfaces near the top of the conversation list when referring to amplifiers. Unlike the tuner spec that doesn't duplicate realistic conditions, or the distortion spec that is beyond audible limits, the damping spec has its own shortcomings.

The damping spec was intended to provide a value that showed the ability of an amplifier to provide electrical braking to the speaker after the music signal had ended. The theory is that an amplifier with a low source impedance will provide a near short circuit to the moving coil of the speaker. This would, in effect, produce something known as dynamic brakes, similar to those used in electric vehicles and some power tools.

The problem with dynamic braking of speakers is that they are powered by voice coils that have high resistance values. This very resistance prevents the damping from being as effective as it could be otherwise. If a speaker has a DC resistance of 3 ohms and it's considered to be in series with the amp, it makes little difference if the output impedance of the amp is .02 ohm or .0002 ohm.

As long as the engineers dish out the specs, the salesmen will quote them and the audiophiles will converse about them. It has always been this way and it is not likely to change - after all, that's half the fun of audio. If we couldn't talk about our systems, we would have no other choice but to spend our time listening to them. If we want to make use of the specs, then we should take the time to understand their importance and real world value. Many specs are very important and others are certainly of less importance. It seems that understanding the spec is only part of the battle. Understanding its real value seems to be the difficult part. In our test reports, we publish the typical "expected" specs, but in our limited text, we try to emphasize the important ones.

Really being able to place a value on the specs enables us to make better choices when it comes time to purchase or upgrade our systems. Spending a lot of money on something we cannot hear is not usually very wise. Poor choices can lead to disappointment and frustration with our investment and less enjoyment of the music, which is, after all, why we build systems in the first place.