Even if it WERE possible to get rid of all but a few low frequency resonances, why would this be a bad idea? Because wire acts much more like a musical instrument than most people suspect. Instruments with only low frequency resonances are fine when part of an orchestra or band. But I suspect that few would find a band made up entirely of bass guitars that interesting.

Resonances have been misunderstood. They have been thrown into the pigeonhole labeled "distortions." However, they rightly belong with "frequencies" in that both the frequency response AND the resonance response of an audio system need to be reasonably flat and even. Why? Read on.

Can I Hear The Effect Of Mechanical Resonances?

It depends on your listening skill and resolve.

Here is a quick test:

Let your system warm up for at least an hour beforehand if you want to maximize this test's validity. Pick a piece of music that has plenty of high frequencies in it--if possible something that is on the edge of being harsh or irritating. Here are two of many possible scenarios:
1. You are an orderly person and there are no CD jewel cases piled atop your CD player/transport/stand. 2. You are casual, and jewel cases and other objects are in residence all over the equipment stand.

Test for scenario #1:

Step 1. Listen to the first 30 seconds of the piece of music you have selected. Do this two or three times.

Step 2. Take a half dozen CD jewel cases, your car keys, and a dollar's worth of change and place them all on the top of the CD player/transport.

Step 3. Listen again. The upper harmonics will be enhanced. The system will sound brighter, and the music will probably be more irritating. Some will consider this difference to be insignificant and might not benefit at this time from continuing.

Test for scenario #2:

Step 1. Listen two or three times to the first 30 seconds of the piece of music you have selected. (Make sure there are at least a half dozen jewel cases and other metallic/plastic objects to remove.)

Step 2. Take EVERYTHING off the top of the CD player/transport. Also take ALL jewel cases and non-essential paraphernalia off the equipment stand.

Step 3. Listen again. The upper harmonics will be reduced. The system will sound duller and the music less irritating. Some will consider this difference to be insignificant and might not benefit at this time from continuing. An Insight Into The Effects of ResonancesA flat frequency response is supposed to be a major prerequisite for system neutrality. Unfortunately, our ear/brain combination is so keen that a flat frequency response is just one of the many steps necessary for achieving a musically satisfying audio system.

AXIOM #1: Because of the tunneling effect and piezoelectric and triboelectric properties, wire is microphonic. As a result, energy from a mechanical resonance affects the flow of electrical energy through a conductor in such a way as to audibly emphasize the notes and overtones that coincide with the frequency of that resonance. If we change the way a conductor (wire or PC traces) vibrates and/or resonates, we change the way it sounds. Thus, in a sense, wire can be thought of as a "mechanical" tone control.

All resonances affect the tonality of the sound of your audio system, whether they are electrical or mechanical...or a combination of the two. The electrical properties that cause wire and PC board traces to become mechanical tone controls are today just coming into focus. All materials have mechanical resonances; change the size, shape, and composition of a part, and its mechanical resonances will change. Even when the circuit and parts stay the same, a prototype that is MADE differently from a production model will SOUND different. (This statement comes as the result of personal experience and from conversations with other manufacturers.) Why? Because materials such as the chassis and mounting hardware will differ, the mechanical resonances will differ, and these resonances will electrically highlight different parts of the signal's sonic spectrum, so the sound coming from your speakers will have to differ also.

All audio equipment can be tuned. Because it can be tuned, it then has properties like those of a musical instrument, and SHOULD BE CONSIDERED A MUSICAL INSTRUMENT. All musical instruments have a characteristic tone...so do all audio system components.

This is a major reason--and possibly the fundamental reason--why today's conventional engineering practices alone are doomed to perpetuate the design and production of products that are a "Dr. Jekyll" in one audio system, and a "Mr. Hyde" in another. The significance of an audio component's resonances, to both consumer and designer alike, is a hidden aspect that confounds and confuses those seeking to build a truly enjoyable system. It "confounds and confuses" because without an adequate understanding of how resonance affects a product's "sound," designers cannot build nor can consumers buy a component that sounds accurate AND musical in any and all systems. I Thought All Resonances Were Bad. Aren't They?A room consists of walls, a roof, and a floor. Because of this, rooms have audible resonances called "standing waves," which are unavoidable. All too often, an unfortunate ratio will exist between a room's dimensions (length, width, and height). This ratio will cause some bass frequency standing waves to exist in isolation with no nearby resonances. When this happens, some bass notes will sound much louder than other bass notes. (The softer bass notes will not have coincident room resonances to amplify them.) Very lumpy (ugly) bass will be the result. Fortunately, an acoustician can design a room's dimensions so that the resulting resonances will be evenly distributed. In this case, the contributions of the room resonances will be friendly in that all bass notes will be treated equally, and the bass will sound much better. This highlights the approach to which this essay subscribes: resonances are unavoidable...make them friendly, not ugly.

(Unfortunately, most of us do not have the luxury of choosing our room dimensions, and the sound of our audio systems usually suffers. For more information about room resonances/standing-waves see Appendix A.)

Today's engineering test methods are centered around electrical parameters that are almost as old as the telephone. They do not reveal information about a component's mechanical resonances. Could these resonances cause a component to sound good "here" but not "there"? Yes.

While mechanical resonances contribute to the sound of everything in audio, these contributions are NOT always detrimental. Resonances are a fact of life...as is the asphalt used in our highways. And like asphalt and room resonances, an audio system's mechanical resonances are annoying only if unevenly distributed. When too much asphalt accumulates in one spot, or not enough (bumps and potholes), a driver's annoyance factor is increased; it is the same with resonances. Bunching and gaps in the distribution of an audio system's resonances, like those in a listening room, are quite audible and distracting; these discontinuities only increase a listener's annoyance factor.

The sum total of the resonances of every constituent part of an audio system (which includes the listening room and everything in it, as well as all electronic components and "accessories") is that system's resonance response. If a system with a reasonably flat frequency response also has a balanced resonance response, the system will sound "good." If the resonance response isn't balanced, this deficiency will be both audible and annoying. When a new component's resonances make the resonance response of the system more even and balanced, the system's sound will become more even and balanced. In this case, the new component's contribution will be judged to be positive. However, if the new component's resonances "roughen-up" the system's resonance response, the sound of the system will also be "roughened-up," and this new contribution will be judged to be negative. This is one of the key mechanisms of "synergy."

AXIOM #2: The "Resonance Response" of an audio system is always a major factor in its musicality. The most musically neutral systems will have their resonances spread out evenly with no clumps or gaps in their distribution...just as the best listening rooms have an even distribution of standing waves. An even distribution of resonances establishes a level playing field for all of music's notes and overtones, allows the proper harmonic balance of the music to be preserved, and maximizes listening enjoyment.

Corollary No.1: No products are universal; just because a signal-path component or an "accessory" sounds good in one place, it does NOT mean it will sound good everywhere.