|Max dB with Doug Blackburn
Back Issue Article
|January 1999Mechanical Resonances and Wire Directionality In Your Audio or
Home-Theater System -- Part 1
How can I break this to you easily, slowly, so gently that you dont even know what hit you?
Well, thats just going to be impossible.
Instead I want you to pull down firmly on the overhead retaining harness, secure your valuables, secure loose items of clothing, and hang on to your eyeglasses. Were going to drop 20 stories straight down, go though a double loop, slither through a diving corkscrew, lurch around an inverted loop, dive into a pitch black tunnel while doing seven barrel rolls before dropping another 20 stories straight down. Then were going to do it again -- backwards. Speeds will exceed 120mph at times, so be certain nothing can fly off of your person during the ride. Begin screaming in 3, 2, 1 -- NOW!
This months discussion of mechanical resonances and wire directionality and how they affect the sound of your audio system (and home-theater system) is just the tip of the iceberg. I fully expect that half of the Max dB columns in 1999 will address various aspects of mechanical resonances and their control. Some months Im going to enlist some of the manufacturers who employ mechanical-resonance control in their products. Mike VansEvers was the first manufacturer to "sign up" (if you are a manufacturer with something to say about your journey into and through mechanical-resonance control and wish to participate in a future article, send me an e-mail). Mike VansEvers is gaining increasing notoriety for his power-conditioning products and power cords. Mike sells a variety of other products as well and bridges three markets: high-end audio, pro audio (studios, etc.) and musicians. Lets get right to the heart of the matter then.
There wont be enough space in these articles to cover 100% of the technical issues to the depth that Im sure some of the more technical readers would like to have them covered. That kind of writing can go on and on and on for many pages -- we just cant deal with it here at SoundStage! What I will do is provide some real-world verification -- examples of things any reader can try on his or her own and observe the results.
You may think that you dont have any mechanical tuning devices for your system because you never bought any cones, Shakti Stones, Shun Mook Mpingos, sorbothane feet, Navcom feet, VPI Bricks, Cable Jackets, any number of ferrites, Vibrapods, Bright Star Air Mass/Big Rock/Little Rock, Townshend Seismic Sink, Whatchamacallits, etc. All are examples of commercial products which, despite claims made for them to the contrary, do 98% of their "work" as modifiers of resonances in whatever part of your system they come into physical contact with. The fact is, you do not have to invest in commercial products in order to introduce new resonances into your system or to move existing resonances around so that they become more pleasing. Certainly you can use commercial products, but there is no guarantee that the commercial product will beat, in any given system, something else from your pocket, your trash can or from a home-improvement store. Now before the commercial resonance-control device people send out the hit squad, let me make this perfectly clear: Commercial products typically look much cooler than some random object you might use instead. Commercial products are often easier to use than some randomly selected item. And commercial products often have a "body of knowledge" existing about them that says they are often highly effective when you place them in certain locations or orient them a certain way. So commercial products do have built-in support systems going for them, which helps justify some of their cost. When you select your own resonance tuning/control materials, you are on your own to determine where in your system they sound the best or if they are an improvement at all.
What kinds of everyday things could be resonance tuning/control objects? Got a coin in your pocket? Or several? They are tuning devices. A button off your shirt? Another tuning device. A credit card or laminated drivers license? Tuning device. More? Belly button lint, wood blocks (but pine seems to not sound very good), paper, a pen, a CD jewel case, a socket wrench, a ball of aluminum foil, a candy bar, a sandwich, a glass of milk. They are all mechanical-resonance-control devices because they have mass and because they themselves will resonate in some fashion in response to external stimuli. Im being a little silly, of course, to get you thinking about other objects you could use that are more practical.
Mike VansEvers: Wire is a mechanical tone control; change the way it vibrates/resonates and you change the way it sounds. Every audio product contains wire in some form or another (circuit-board traces, fuses, transformer windings, etc.); every audio product is tunable because you can change the resonances in those wires.
What does Mike really mean by this? And why is it important to you? Understanding this first principle and accepting its incontrovertible existence is the first step to gaining appreciation for the scope of this whole mechanical-resonance issue. Current flowing through a wire induces an electrical field around the wire -- the more current, the bigger the electrical field. When there is a large current flow -- as in a downed electrical power transmission line or in the cables carrying electricity to something like an elevator motor -- the force of the field around the wire is so strong that the wire will actually physically whip around if it is not restrained by serious force. In audio components, there is never enough current to cause wires to move enough to be observable to the human eye, but they still vibrate on a smaller scale. Pulsating DC (like the output of a power supply in any audio component) and any AC voltage or signal are what induce vibrations (resonances) in the wires, in any conductor actually. This vibrating/resonating wire, when carrying an audio signal, causes changes to that audio signal. Im not sure I understand precisely how this happens yet, but there are just too many examples of it happening to deny that it does happen. Youll find that out for yourself when you try some of the verification exercises.
We know that the string of a guitar or violin or other instrument resonates at different frequencies depending on how tight the tension on the string is and on where the musician places the fingers to create specific notes. An electrical wire has a natural resonant frequency and profile, a spectral fingerprint, which is controlled by the length, number, size, and geometric layout of the conductors; the materials used in making the wire; and how tightly all the elements are bundled together under the wires insulation. If you grab this wire somewhere along the length with thumb and forefinger, you set up a "string resonance" just like the string of a guitar or violin. The resonant signature of the wire has now changed just from grabbing this wire at a single point. Touch the wire at another point and a different node appears. Touch the wire at multiple points and multiple nodes are created. The wire does not have to be stretched tight for these resonances and nodes to exist. Do you want these nodes in your interconnects, power cords and wires inside components or not? Depends on the system and depends on where the nodes are within the audio spectrum. Some nodes will be better-sounding, some will be worse-sounding. What you need to do is prove to yourself that these wire resonances and string resonances exist, and that moving these nodes around does change the sound of the wires in your system.
Verification exercise #1: On any part of any wire in your system where the wire is touching the floor, lay a moderately heavy book on the wire and evaluate what happens to the sound. It will help to have a second person laying the book on the wire and lifting it up so the sonic change can be evaluated.
Verification exercise #2: Raise any cord in the system (perhaps a power cord) completely off the floor using some kind of supports (cups, tubes, small boxes, whatever) and evaluate the sound of the raised cord versus laying on the floor. There is nothing electrical of any real consequence going on here; the change you hear is strictly a mechanical thing. You arent listening for one to be better than the other, just for differences. If you then move the objects lifting the wire off the floor around so that they touch the wire in different places, the sound will change again.
Mike VansEvers: Everything, including those things you just KNOW can't have a sound, have a sound anyway...it may be subtle, but it is there. To know what something sounds like, you have to build it "That WaY," not "Another wAy," because the different ways DO sound different -- .the same circuit and parts on a differently laid out circuit board WILL SOUND DIFFERENT, even if they measure the same.
I suspect this statement comes from Mikes years of fabricating power conditioners and power cords. Mike has told me on more than one occasion just how hard it can be to create two identical-sounding power cords. Small differences in wire lengths, screw tightness, amount of solder in a joint, all the little details make each handmade example of a specific product unique-sounding. He can only get so close to making all examples of any one product sound identical. Fortunately for most of us, the differences end up being so small we dont even notice. But for Mike or one of his technicians who have heard ten or hundreds of examples of each product, there are subtle differences.
Mike VansEvers: Prototype equipment has to sound different than production equipment. Use prototypes only to see if a circuit or concept works. I build in the features and their relative placements, then I voice the production version of the product.
As this is written, Mike is struggling with the tuning of the new balanced power conditioner, not because it sounds bad, but because the tuning needs to be reproducible in each production unit. It can be a lot easier to tune something to sound good when you only have to worry about ONE of something. When you have to consider that you will build 50 or 100 or more of a product, tuning for production becomes a significant exercise.
Mike VansEvers: Change a single piece of wire's direction and it is audible.
Alright, this puts us right in the middle of that dropping corkscrew. Wire manufacturers for years have been labeling wires with directional arrows. Sometimes these are there because of a specific grounding/shielding configuration the manufacturer wants maintained. But most of them are a result of the wire manufacturer noticing that the direction the signal travels through a wire does make a sonic difference. My first experience with this was years ago with Kimber KCAG interconnects, which were not labeled for directionality. I moved and hooked everything up in the new location and it was literally weeks before I realized the garbled sensation I was getting from the system was because the KCAG was all mixed up, some in the "right" way and some reversed. I found that using a single speaker/channel at a time, I could quite easily determine which direction was "right" for any given interconnect. Once they were all in "right," it was only a matter of two days or so before the system came together for the first time in the new location. If a wire has been in "backwards" for some period of time, it breaks in and sounds better in that reversed direction than it did initially, just as if the wire were brand new and breaking in for the first time. Reverse a wire and it takes a couple of days of use in the reversed direction for the wire to settle in and sound its best. This settling-in improvement is smaller in magnitude than the difference in sound from running the wire backwards, so you can tell immediately upon reversing a wire if it is in the best direction or not.
Mike VansEvers: Different wire terminations sound different. For instance, a soldered connection sounds vastly different than a quick disconnect -- different, not better.
The manufacturers lament -- to solder or to crimp? One just has to be better, right? Mike doesnt think so. It all depends on which sound is most complimentary at the connection in question. I havent examined the difference in sound between hundreds of individually soldered or crimped connections, so Im going to go with my gut on this one and with the guy who has listened to hundreds of specific connections, soldered, crimped or in a connector. This "different, not better" mantra ought to be your chant while practicing the rites of system resonance control. Which sound is the "better" sound? The one that pleases you the most.
Mike VansEvers: "Better" is the most misused and misunderstood word in the audio lexicon. It is comparative, situational, and relative...not ever, never "always." One size does not fit all; better "here" does not always imply better "there."
Audiophiles usually hate this kind of answer. Things are simpler to live with when they are black and white. I cant tell you how many people write to SoundStage!, either to Talk Online or to individual SoundStage! writers, and ask people to just tell them what to buy. These people dont want to live in the gray area and spend months studying the market and looking for their ideal product. They are more interested in being pointed at something good and reliable; it doesnt matter that they never heard of the company before and maybe never even saw the product before buying it. When it comes to tuning and to components, there simply are no absolutes except for one: Everything matters. At some point you will realize you can make your system sound 20 shades of different by adjusting the resonance tuning -- and that there is no possible way to select any one of those 20 tunings as "best." Pick one of them and enjoy it. If you get tired of it in three months, you dont have to spend big bucks on a new component unless you want something new. You could just re-tune the system again to get it to sound like you spent big bucks on a new component.
Mike VansEvers: A lot of subtle changes can add up to a big change.
A big statement in just a few words. As I try to reveal the whole concept of mechanical tuning and resonance control, it is important to keep something in perspective. Ive encountered three "classes" of change in system sound when messing with tuning and resonance control: (1) The first group of changes is what Id call subtle changes, worth pursuing, but not worth losing sleep over. One wood block might not do all that much by itself. Yet when you put, say, 15 wooden tuning blocks in a system, the change can be quite dramatic and well worth pursuing. (2) Moderate changes are the ones that you dont even need to go back and repeat tracks to hear/understand the first time. There arent as many of these as there are the subtle ones, but they sure are obvious. (3) The large changes that take you by surprise. The biggest large change Ive experienced so far was when I decided to see what would happen if I moved a small plastic tool kit, a large plastic tool kit and a vinyl zippered-case socket wrench set. These tools are usually against the wall to the left of the left speaker in a group. You cant even see them from the listening position because the arm of the couch on the left side of the room blocks your view of them. Yet when I picked these up and moved them to the back of the room, the sound got hard, bright and brittle. Needless to say, now that I know this happens, the tool kits always go back to their proper positions when Im done with them. I could have blamed the change in sound on 100 other non-related things, like the speakers or the preamp or the cables. Can you imagine calling a certain pair of speakers bright and brittle-sounding only to find out days, weeks or months later that your tool kits werent in the right spot? How many reviews and reviewers could these kinds of things have affected over the years? How about every review and every reviewer! Can you blame us for telling you to audition things for yourself?
Besides the 15 blocks of wood adding up to a significant change, removing a number of random objects from the vicinity of my system made significant sonic changes. Removing one of the two small CD racks/holders on top of an unused rack was a significant change for the better -- removing both sounded worse. Removing a crescent wrench and a package of pipe cleaners from the floor near the amp was significant. Installing one sand bag at a time was small, but putting in ten at one time was big. Combined together, all these changes were quite a revelation.
Mike VansEvers: Distributing resonances is a technique that I use for making the sound of a product more uniform. Why distribute resonances? Because they are audible. For example, an even coat of paint, regardless of color, will generally look better than a spotty coat of paint that is thick in some places and almost transparent in other places. Different wire gauges, different colors, different terminations -- an even distribution of resonances sounds "better" most of the time.
Lets imagine a guitar with six strings all tuned to the same G. You could still play music on it, maybe, with a lot of practice. But most people would be irritated out of their minds by the sound because of the overriding resonances from all six strings being tuned to G. You dont necessarily finger all the strings all the time, so there is going to be a heck of a lot of G coming from the guitar no matter whether you flat pick, finger pick or strum. But put six different strings on the guitar and tune them to different notes and you distribute the resonances and most people love the sound of the result. Works the same way in your audio system. Lots of different spacings between wire lifts, different kinds of feet and shelves under different components -- anything you can do to spread out the buildup of resonances, the better the sound you will get. One thing Ive seen done is one of the worst things you can do, sonically. Bundle a bunch of cables together and wire tie all of them into a big bundle. This can create the same string resonance in every wire in the bundle, which is not optimum for good sound. You get better sound if each wire is free to be located away from the other wires -- distribute the resonances. If the wires have to touch each other or the floor or a wall, try to get it to happen at different points along the length of each wire so that none share the same resonant signature.
Distributing resonances means spreading them out so that they dont all build up at one or several spots. Spread out, each one is lower in level, less obvious. Many mechanical-resonance-control devices or materials actually work by distributing resonances, not eliminating them. Other devices like isolation bases and soft squishy damping feet try to eliminate some resonances completely. also worthwhile where practical and possible. So soft squishy feet will always sound better than hard resonance re-distributing feet? No, you can never tell until you try both. My personal rule is "never sell off any feet because you never know when theyll be needed." Id stopped using Navcom feet years ago in favor of other, better-sounding (to me) alternatives. I surprised myself when trying Navcom feet under some Power Line Conditioning equipment. They were the best-sounding feet for that application.
Mike VansEvers: Wire has a direction because wire is created mechanically. The internal structure of a copper crystal (face centered cubic, FCC) is reoriented by the physical forces imposed upon the copper by the "die" that the copper is drawn through during the process that turns a 1/4" rod of copper into the wire we use in our audio systems. This is not a one-step process. The copper rod has to be redrawn many times to get it down to the size used in audio cables. During this process something happens which causes wire to have an audible direction. I used to think that wire direction was the funniest thing (stupid funny) I ever heard audiophiles talk about, .until I started making speaker cables. That was a most unpleasant awakening! When I discovered that wire had an audible direction, it meant that I then had to listen to and mark every piece of wire used in my products! Every one of my products has a construction notebook which lists wire: direction, length, and color. (Yeah, color too. Another damn eye-opener that had been impossible to conceive of!)
There are some people who like to try to prove to other people just how audible the correct electrical polarity is for proper music reproduction. These people claim to be able to listen to a recording and determine within a short listen whether the polarity of the recording is "correct" or "reversed." When they hear a "reversed" recording, they will jump up, and swap the "+" and "-" speaker leads on both speakers and, voilą -- wonderful sound in proper polarity. This is complete baloney. What they are hearing is not the effect of reversing the electrical polarity of system. What they are hearing is how the system sounds with the audio signal traveling backwards though the loudspeaker which contains connecting wire, wire in the voice coils, wire in component leads, wire in the inductors in the crossover, and the capacitors themselves. They all sound different when the signal travels though them backwards.
Verification exercise #3: To hear the effect of reversing wire directionality, two exercises:
A. Reverse any pair of interconnects.
B. (This will not be possible for everyone, requires a polarity reversal switch on CD Player or DAC)
First, reverse the speaker cables at the loudspeaker (1 polarity reversal)
Next, reverse the polarity of the music using a CD player or DAC with a polarity-inversion switch ( adding a second polarity reversal, which means the system now has "correct" polarity again).
Finally, listen to familiar music. You still hear a big difference in sound quality because you reversed wire directionality in several locations all at one time. The second polarity reversal eliminates polarity itself from being the source of the sonic difference. All the sound difference is from changing wire direction. You can only do this verification exercise with a CD player or DAC which inverts polarity in the digital domain. Do a polarity reversal anywhere else in the system and you will get into wire directionality issues again. This verification exercise requires a digital-domain polarity reversal to reveal the truth -- there is no other way to hear and understand what is really happening and how powerful wire direction really is.
Out of space for this month already. If you find it difficult to accept what Im saying this month, please do the verification exercises. Youll learn a lot and begin the process of unraveling the importance of resonances and tuning and how the sound of a system is affected.
Next month, a break from mechanical resonances: "Bass -- Big, Deep, & Powerful." Get it in your system and understand it better.
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