Introduction

This is the first of a series of articles that will relate sound to the human experience in a way which is not only factual, but by the end of this article, can be proven on virtually any audio system in existence today. These articles will be written in the words of this lay writer where I will attempt to communicate and interpret, in my own words, the concepts which have been experimented with and/or understood by the writer as communicated through an exchange of concepts with Mr. Michael Green. I say "virtually" any system because "High End" audio component design seems to be stuck in the type of train of thought, "the world is a flat entity" belief, that was predominant prior to the fifteenth century. To begin, let's first review some very basic principles of physics that we can all relate to in our daily lives and how these principles apply to the reproduction of sound. We'll begin by defining what is a sound signal and then proceed to explore, on a basic level, how a sound signal is created, captured, stored, manipulated, reproduced, interacts with the environment and finally arrives at the listener's ear. The key factor related to the above sequence has to do with understanding that everything in the universe consists of atoms whose subatomic components are constantly in a state of flux. We will call this state of flux vibration(s). Our goal, with audio components, is to attempt to manipulate these vibrations in such a way that we can maintain the integrity of these vibrations on the way to reproducing sound. As we shall see, this systematic controlling of vibrations will lead us from the current world of factory preset fixed tuning techniques into the new world of user controlled variable tuning of audio systems. By the end of this series of articles, even the non-technical audiophile, music lover or videophile will possess the basics in order to achieve the highest levels of performance and derive the most satisfaction from their current and future audio and/or home theater systems.

The Original Signal

All sound signals consist of mechanical vibrations, be they created by vocal chords, a drum, flute/ recorder (made from the hollowing out a tree or branch), a metallic horn or a tensioned string instrument. Not only is the created sound affected by the mechanical conduit (i.e., the labyrinth of a horn instrument or the string of a violin) through which it passes on its way to "creation" and subsequent reproduction, but can be manipulated in such a way as to maintain (or detract from) the integrity of the fundamental tone and its associated harmonic structures. Those of you who are old enough, or had elementary science projects, will remember the making of walkie-talkies out of two empty cans connected by a common piece of string. We could use the same can (on our end of the string) as a "microphone" to talk or as a "transducer" (speaker) to listen. The "vibrations" created by our voice would be spoken into one can (a mechanical conduit), they would travel down the string (another mechanical conduit) and, on the other end, could be heard by a friend who would hold up his/her end of the string/can to their ear. By increasing the size of the can at each end, we could increase the amount of harmonics associated with the tone on the listening end (due to a decrease in the resonant frequency caused by the increased mass of the can) as we would also increase the amount of harmonics on the speaking end.

This simple illustration seems to have been lost in the world of audio today. Current engineering philosophy has seemingly wandered down a path of fallacy where it seems to have forgotten that (1) the very signal we are trying to reproduce was reproduced by mechanical vibrations, that (2) the final signal is still not absent of the original mechanical vibration and that (3) we do not want to destroy any portion of the original mechanical vibration through absorption because we do not want to destroy or take away any of the harmonics of the original fundamental tone.

All sound that is produced has a fundamental tone or frequency and, much like a stone thrown into a pond creates ripples around the area of initial impact of the stone, has overtones or undertones commonly referred to as harmonics. These harmonics are in direct mathematical proportion to the original fundamental tone and as we increase the mass of the conduit (i.e., horn or string) through which the tone is created, so is our ability to increase the amount of associated harmonics by the lowering of the resonant frequency of the conduit. We all know that a larger diameter guitar or violin string will play a lower note than a thin string and create more harmonics. By tightening or loosening the string on a guitar or violin, we can then "tune" that string to produce vibrations which will be either higher or lower in pitch (resonant frequency). Likewise, if we lengthen the string, we can affect the pitch as well as the harmonics produced when strumming the string. If we take this one step further and vary the environment, we can create "echoes" of this sound in a hall or "deaden" (destroy some of the original harmonics) the sound if we create it in a room with wall to wall carpeting, heavy drapes, overstuffed furniture or anything else, that is absorptive, in the listening environment.

The goal of audio reproduction should be to reproduce, in the final format to the listener, the original sound with all its associated harmonic structure intact. This can only be done if we treat each conduit along the "reproduction" path as a true reproducer of sound (i.e., a true musical instrument) in and of itself and keep in mind that the electronic signal passing through the audio reproduction conduit (i.e., capacitor, resistor, circuit board, transformer, etc.) will be affected by the material characteristics of the conduit itself. Can you imagine a violin or guitar made out of or lined with rubber or trying to get sound out of a rubberized horn? Any "absorbent" materials along the path of the conduit will "soak" up some vibrations which will subsequently alter the signal passing through it. This would be totally contrary to the objective of true high end audio since any absorption of vibrations would be a lessening of the harmonics of the original tone. Every conduit will also have a resonant frequency of its own, based on the material characteristics of the conduit, so we must be able to "control" any erratic vibrations in the conduit created by the conduit itself. I say "control" here because we do not want to "deaden" the conduit because then, by definition, we then "deaden" or alter the harmonics of the original tone also. So, every conduit or component in the musical chain must be designed to be tunable.

The Path to Musical Reproduction

A musical sound (the fundamental tone and its associated harmonics) is created by vibrating a mechanical conduit. The created sound emanating from the conduit pressurizes air, interacts with the environment in which it is created and finally arrives at a point of capture. We then "capture" the created sound with a vibrating electromechanical (electrical and mechanical parts) element or conduit called a microphone, pass the signal along another mechanical conduit (the wire attached to the microphone) and ultimately transfer the captured vibrating energy, the sound, to some type of recording medium. As elementary physics teaches us, energy can neither be created nor destroyed, so we then take one form of energy, capture it and store it in another form of energy, usually on tape. The format of this energy can be analog (a continuous signal) or encoded as a digital (zeroes and ones) signal. Since the precision of the digital encoder is beyond the scope of this article, suffice to say that the original fundamental tone and all its associated harmonics must somehow be preserved. Just as more decimal places give us more precision in dealing with decimal digits, more bits (binary digits) would hopefully yield more precision (maintain the integrity of the original tone and its associated harmonic structure ) when dealing with a digitally encoded signal. Either way, we must somehow preserve the original sound.

Once the signal is recorded, it can now be further manipulated/mixed (mixing will be covered in a future article) and then be transferred to a playback medium (CD, LP, etc.). Again, the objective is to maintain the fundamental tone and its associated harmonics throughout the entire recording process all the way to its final form on a recording medium.

Each conduit used in the creation, capturing, recording and reproduction of this musical signal must be "tunable" (user controllable) if we really want to have a final product that has the original signal intact. The conduits would also include cables since they are simply carrying this electronic signal from one conduit to another (i.e., microphone to recorder). The signal carried by cables is derived from the same mechanical vibrations we originally started with in the creation phase. Again, heavy, absorptive materials around the cables (similar to the way heavy drapes will affect the sound in your listening environment or rubber would affect the creation of the sound) should be avoided since we do not want to "deaden" the original signal being transported by the cable.

Home Reproduction of Musical Sounds

In the home today, most audio only based systems have a digital front end source such as a CD player. So as not to offend any hard-core audiophiles who are also vinyl lovers, we will touch on vinyl playback briefly. Vinyl playback consists of utilizing a mechanical conduit (a phono stylus) to retrieve an analog (continuos) signal from the tiny grooves of an LP recording. This stylus has the most arduous of tasks in that it must maintain constant contact with the groove walls of the record and transfer mechanical energy it picks up which will finally be transformed into an electrical signal by the cartridge to which the phono stylus is attached. This captured and transformed signal is then passed down a mechanical conduit consisting of fine wires. These fine wires are inside another mechanical conduit, the tone arm. Here again, we want to avoid the use of heavy damping materials so as not to disturb the harmonic structure of the music embedded in the electronic signal being passed on its way to further amplification by the phono stage in the preamplifier. Those of you who have been vinyl lovers over the years will remember how turntables of the past were designed with "rubber" material platter mats to support the spinning record and to dampen any ringing in the patter. These "rubber" type mats subsequently gave way to designing platter mat materials, such as acrylic, which are similar in properties to vinyl itself. The reason for this change in design was to provide a platform for the vinyl record to rotate on that was similar in resonant characteristics to the vinyl. This change in engineering design not only produced more accurate reproduction of vinyl playback harmonic structures and, if you think about it, is consistent with applying materials of appropriate resonant characteristics to instruments in the creation phase of the original sound and conduits used in the capture, storage and transfer to playback medium phases.

Along with the utilization of new materials in turntables built for analog playback came the application of mechanically grounding the turntable by replacing the rubber feet on the turntable base with pointed, metallic cone feet. Not only did audiophiles experience a significant increase in performance of their turntables, but they also experienced new levels of harmonics in music played back on these mechanically grounded turntables simply by removing the "rubber" damping type feet and replacing these feet with metallic cones that provided the mechanical grounding of vibrations in the turntable. These vibrations in the turntable chassis or platter previously could be "picked up" by the stylus and played back along with the mechanical energy being generated and picked up from the LP itself.

Similarly, with digital playback systems, unwanted vibrations, either from the motor within the CD player, the transport that rotates the CD while it is being read by a laser mechanism or electronic conduits in the digital to analog converter (DAC) involved in the conversion of digital data to an analog signal, would best be dealt with by orderly controlling these vibrations with mechanical grounding, and ultimately with variable tuning (the ability of the user to control the rate and amount of drainage of vibrations). With CD playback, light energy is used to transform mechanical energy (bits) encoded on the CD into electronic digital signals that ultimately get converted into an analog signal and hopefully played back as the original sound signal created, with all the associated harmonics intact. Just as vibrations can interfere with the reproduction of vinyl analog signals, vibrations can also interfere with the accurate reproduction of digital signals if these vibrations somehow interfered with the laser mechanism's ability to accurately read the encoded digital information on the CD or the DAC's ability to convert the digital data to analog. However, unlike vinyl reproduction, we can control the rate of flow or drainage of unwanted vibrations more precisely in digital playback through variable tuning. We can precisely control the amount and rate of drainage of unwanted vibrations so as not to disturb the harmonic structures embedded within the digital encoding on the CD that hopefully we captured and stored intact in the earlier phases in the reproduction process.

Be it vinyl or CD playback, the signal produced is then passed from one conduit (the phono turntable and its associated conduits or CD player and its associated conduits) to the next conduit in the chain, the interconnect cable, that ultimately delivers the signal to our electronic component(s). Since our original mechanically created signal is embedded in the electronic signal being carried by the interconnect cable, the use of any heavy damping materials in the jacket of the cable will have a detrimental effect on the signal arriving at the input jacks of the next component in the system. The interconnect cable is exposed to environmental influences such as material resonance, length of run, external vibrations, any static electricity residing on surfaces that the interconnect comes in contact with, and RFI or EMI in the air. All of these must be dealt with in some way by the interconnect cable designer without disturbing the harmonic structure of the sound traveling through the cable en route to the next component in the chain. If we had some way, a Mechanical Transfer Device (MTD), that would drain unwanted vibrations away from the interconnect (or speaker) cable instead of using absorptive materials that "deaden" the sound, we would be able to better preserve the original signal and its associated harmonics intact. We will talk more about MTD's for cables (speaker and interconnect) in a future article.

Once the signal is passed to an electronic component, it will then pass through a series of conduits. These conduits may be capacitors, resistors, transformers, circuit boards, computer type ribbon connection conduits, PC chips, wires or some other type of conduit. Each conduit through which our signal passes will be composed of a material that will have a resonant property of its own and lend some of its "character" to the original signal. This "character", which interacts with the signal passing through the conduit, will produce a sound that is pleasing to the ear or one which not. So, we want to drain the vibrations away from each conduit within the component in a controlled manner so as not to disturb the sound signal passing through each of these conduits. We then must create a path for these unwanted vibrations to be drained out of the chassis of the component so that these vibrations can find their way to "ground" just as electricity wants to flows to ground.

Energy always wants to move to a lower state. Electricity and vibrations (another form of energy) want to run to "ground". Anything interfering with this natural flow will obstruct the reproduction of the original music with all of its harmonics intact. Mechanical grounding (providing a path for vibrations to flow naturally to a lower state) is part of a user controllable way to maintain the original fundamental tone and all of its harmonics intact. If we can vary the rate and the amount of drainage of these vibrations away from the component, we can preserve the sound signal and its harmonics on its way to the next conduit outside of the component chain, the speaker cable, and ultimately to the reproducer of the sound, a transducer commonly known as a loudspeaker. Once the signal arrives at the loudspeaker, we now want to convert the electrical signal into sound waves generated by the transducer in order to pressurize the air in the room.

The sound produced by the loudspeaker will be affected by the resonant characteristics of the materials of each conduit that comprises the makeup of the loudspeaker. We want to mechanically ground the loudspeaker as well. Here also, it is advantageous to have a way to control the rate and amount of vibrations we wish to drain away from the loudspeaker. If we drain at too slow a rate (too little), we can produce an overly ripe (warm) sound and if we drain too much (too fast a rate) we will produce a hard sound to the music devoid of harmonic structures. This same principle of drainage will apply to electronic components. So, if we have a way to vary the drainage of vibrations away from the speaker (and electronic components), we should be able to "tune" the speaker to produce just the right amount of harmonics along with the original fundamental tone. With this control in the hands of the user, the user now can adapt the sound to his or her environment, playback level and personal liking.

When you apply the concept of tunability to loudspeakers (I'm not talking about tweeter or midrange controls found on some speakers today) and if you have spent any time experimenting with sound volume levels of your system in your listening environment, you will probably have noticed that at a given volume playback level, your speakers will give you too little, just the right amount of or too much harmonics (at which point, the room will start to overload). When loudspeakers are designed like musical instruments (variable tuning) and the end-user is given the capability to tune the associated harmonics at a given playback volume level in the room, you will have optimum sound for that volume level. This cannot be done with a speaker that is not tunable nor with fixed frequency factory preset tuning devices. With factory preset tuning devices and speakers that are not tunable by the user, you take your chances on your purchase and hope the speaker sounds good in your listening space and hopefully, after seemingly endless placement attempts, will give you what you want in sound quality. Instead of this ongoing playing of musical chairs with your loudspeakers that inevitably usually doesn't function at the optimum performance level in the home, the use of variable tuning, incorporated into the design of the loudspeaker, provides the user with the ability to vary the pitch and harmonics of the sound of a tunable speaker without affecting the relative frequency relationships of the tones in the music. This approach to speaker design is similar to the design of a musical instrument that is tuned by the musician to the characteristics of the hall in which the musician is playing. The user now has the ability to variably tune the loudspeaker to the home listening environment and to his or her preference by varying pitch and harmonic richness. This is all accomplished by controlled draining of vibrations away from the speaker to ground.

Once the air pressurized by the speaker becomes "sound" in the room, it starts to interact with the total listening environment (walls, ceiling, floor, furniture, objects in the room, plants, tables, pictures on the walls, etc.). Every room will have its own resonant characteristics, and should be considered a conduit (system component). As far as audio reproduction is concerned, the room is also the largest audio component of every system. At the beginning of the article, I gave a few examples about how if we changed the size (actually mass) of a conduit, we will increase the harmonics the conduit will produce. If this is true, then the listening room should be able to produce a larger amount of harmonics than any other component in our system. However, we must be careful to control the harmonics produced by concentrating on areas of the room called Pressure Zones. The pressure zone areas of a room are the areas at which the surfaces (walls, ceilings, floors) of the room intersect with each other. For the purposes of this article, we will narrow down our focus to two key pressure zones to concentrate on controlling in the listening room - the mid wall pressure zone (where the middle of the wall intersects with the ceiling) and the corner pressure zone (where two walls intersect with the ceiling). Try a little experiment in your listening area. Play your system at a reasonably normal to high listening level, get up on a step ladder and listen to what you hear at the two pressure zones mentioned in the last sentence. You will hear an even louder increase of the harmonics in the bass and other frequencies at each of these points in the room on each wall than you may be hearing from your listening position. The increase in harmonics you will hear near the ceiling/corner/wall intersection is the result of a horn loading effect being creating by sound wave vibrations trying to migrate to ground, having nowhere to run and being "loaded" back into the listening room. The excessive harmonics you will hear, produced by the buildup of acoustical energy at the mid wall pressure zone point in the room, is the source of echoes where energy runs back and forth and side to side across the ceiling of every room. If we can variably control this buildup of energy by the use of a tuning board, placed at these pressure zones, and whose resonant frequency we can control, we will not only have the capability to control the pitch of the sound in the room, but also the harmonic richness produced by the room/speaker interaction. By using variable tuning at the pressure zones in the room and by the use of mechanical grounding and variable tuning techniques on loudspeakers and components, we can now reproduce sound with the harmonic richness, that we've all associated with only the most expensive equipment, with well-designed cost effective components.

Finally the "variably controlled" pressurized sound wave arrives at the next mechanical vibrating conduit, the ear drum. What happens after that not even scientists will agree, but somehow the brain interprets what we "hear" as music. The chain of sound reproduction is now complete.

Summary

The original source of sound is by the vibration of a mechanical conduit. This vibrating conduit will produce a fundamental tone and associated harmonics. Once the sound is created, we then capture, store, manipulate/mix, transfer onto a playback medium and ultimately reproduce the sound in our listening environment. Mechanical grounding techniques and variable tuning can be applied to electronics, transducers (speakers) and to the room itself! When listening to our system, we are actually listening to the "room" and its interaction with the loudspeakers and its environment, the components and their interaction with environmental factors (power line noise, sound wave vibrations in the air, RFI/EMI, the resonant characteristics of the material the component is resting on and vibrations created by the conduits that make up the component) and the acoustical properties of the room itself. We shall see in future articles that it is not necessary to spend a king's ransom to achieve good, high end sound. By using variably tuned acoustic controllers on pressure zones in the room, by using mechanical grounding and user controlled variable tuning of the entire listening environment (components, cables, loudspeakers and the room), we can reproduce sound usually only associated with the most expensive of components. Also, by applying this approach (mechanical grounding and user controlled variable tuning) to product design, we could even further more accurately reproduce music in our home listening environments. Again, in future articles, we will cover many of the topics covered above in more detail.