Sounding Board RepairingIts Limiting Factors

By Charles Walter Beach, Springfield, MO

Published 1925

“Mr. Beach has given this subject thorough and scientific study, and this publication will be found of great educational and practical value.” so says the editor of The Tuners’ Journal, Thomas J. O’Meara. This booklet consolidates the six instalments published from October 1925 through April 1926 in The Tuners’ Journal, under the above title “Sounding Board

Repairing”. I hope this will be of interest to the piano technician of today and of the future. I believe that there is something for every piano technician in this historic article.

Instalment 1

October 1925 pp. 232-234

Without a complete, unbroken, unified sound board any piano is crippled, if not useless, as a musical instrument. A bad repair job on a cracked or loose board fails to correct the trouble, and often introduces distressing rumbles, quavers, or reverberating splashes of amplitudes untimed in their travels by improper stresses, weights, or bracings created by these repairs, which once produced are not easily, if ever, overcome. Therefore, it is necessary that the repairman know exactly what he is about when he touches the sound transmitting-amplifying apparatus of the piano.

Strange methods have been employed by tuners to stop the queer rattles, tingles, raspings and noises that accompany and indicate looseness of ribs, cracks in the sounding board or loose edges of the board, but frequently without restoring the tone. Fullness of tone is one of the characteristics of the pianoforte which has made it so popular (forte means strong), and any method that fails to return the parts to their intended relationship one to the other is likely to create a condition of restriction, if not of complete imprisonment, of sections of the board, thus rendering parts at least of the stringed “harp” of the piano dead!

Some samples of insufficient repairs which I have found include cork and wooden wedges between the ribs and the board, between the ribs and the stanchions, between the board and the plate, between the edge and the frame of the case; cords tied tightly across from screws in the board to the posts or the frame; shims driven or glued into widely parted ribs (which should have been drawn back together); screws in the ribs and the board for which holes had not been drilled;

screws too long or too large for the places; too many screws in a given section; failure to have parts firmly together when screws were driven; overhauled screw holes and screws too small for the holes drilled; and even in otherwise good repairs an unsymmetrical distribution of screws. While there are times when cork may be inserted in places to stop rattles which the owner will not pay to have removed in the right manner, and shims may be used with certain restrictions that make them almost prohibitive, yet both methods create restricted areas.

Many questions as to the how and why of this matter may be answered by considering a few basic facts in regard to the nature, ideal condition, purpose, and method of manufacturer of the sound board of the piano. The following interesting facts are collected from many sources and are respectfully submitted to the Naptincs (member N.A.of P.T., Inc., a word coined by Edgar L. Seagrave, president emeritus, St. Louis division) to inspire them, if possible, with a greater awe for the wonders which man’s ingenuity has produced in the piano and the wonders each may learn to bring about in the instruments entrusted to his care, through a better understanding of the elements of which the piano is made.

The sound board of the modern piano is made of selected, straight-grained, flawless, uniformed textured, mountain grown wood from coniferous trees sixty to a hundred years old. It is seasoned to the point most susceptible to vibrational transmission, yet at the same time retains an all-essential elasticity of molecular constituency, supposedly “quarter-sawn,” etc. All of these exacting conditions mean that only a small part of the collected wood proves suitable for use in high grade pianos. Such pieces as do pass are narrow, sometimes not more than three and one-half inches wide, necessitating one of the great tasks of the piano-maker’s art – the fitting together of many parts, with the grains often so closely

matched that keen eyes can scarcely detect the joining. The reason for such care should become more and more evident as this account progresses.

To enable this comparatively frail wood to bear the strain of the tension placed upon it by the strings of the piano, the pieces have to be fitted upon an arch, and to them are glued “ribs,” primarily for the purpose of strength, but to serve also another very great purpose, that is, the equalization of the possibilities of directional vibrational velocities.

By experiment, Tyndall, Wertheim and Chevandier discovered that in wood,sound travels along “three unequal axis,” and the different velocities have actually been determined for the various kinds of wood. Not to burden this article with figures, it is enough to say that the velocity along the grain is about three thousand times across the largest sounding board in one second, or about three miles. Across the grain, that is, along the “ring,” the speed of transmission is only about one-sixth as fast, while across the ring, which, if the board is made of quarter-sawn fir, would be across the grain on the width of the sections, the velocity has been found to be about one-third of that along the grain, or fiber. It is thus to be observed that the relative speeds are approximately expressible in the figures “one,” “two” and “six.”

Bad construction of the ribs, faulty materials, careless gluing of the ribs, and other faults in connection with the rib assembly, have created many dull pianos, - to the unproclaimed shame of their makers. Over all this board-rib-bridge assembly has been placed a shield, in some makes an almost penetrating protective coat of especially prepared varnish, to seal up the glued edges from the dissolution-working effects of wet and dry climates.

As to the traveling of sound in the sound board of the piano, John Tyndall, in his fifth edition of Sound, page 78, says:

We are now prepared to appreciate an extremely beautiful experiment, for which we are indebted to Sir Charles Wheatstone.

In a room underneath this, and separated from it by two floors, is a piano. Through the two floors passes a tin tube 2 ½ inches in diameter, and along the axis of this tube passes a rod of deal (wood, either fir or pine, ed.), the end of which emerges from the floor in front of the lecture table. The rod is clasped by India-rubber bands, which entirely close the tin tube. The lower end of the rod rests upon the sound board of the piano, its upper end being exposed before you. An artist is at this moment engaged at the instrument, but you hear no sound. When, however, a violin is placed upon the end of the rod, the instrument becomes instantly musical, not, however, with the vibrations of its own strings, but with those of the piano. When the violin is removed, the sound ceases; putting in its place a guitar, the music revives. For the violin and guitar we may substitute a plain wooden tray, which is also rendered musical. Here, finally, is a harp, against the sound board of which the end of the deal rod is caused to press; every note of the piano is reproduced before you. On lifting the harp so as to break the connection with the piano, the sound vanishes; but the moment the sound board is caused to press upon the rod the music is restored. The sound of the piano so far resembles that of the harp that it is hard to resist the impression that the music you hear is that of the latter instrument. An uneducated person might well believe that witchcraft or “spiritualism” is concerned in the production of this music.

What a curious transference of action is here presented to the mind! At the command of the musician’s will, the fingers strike the keys; the hammers strike the strings, by which the rude mechanical shock is converted into tremors. The vibrations are communicated to the sound board of the piano. Upon the board rests the end of the deal rod, thinned off to a sharp edge to make it fit more easily between the wires. Through the edge, and afterward along the rod, are poured with unfailing precision the entangled pulsations produced by the shocks of those ten agile fingers. To the soundboard of the harp before you, the rod faithfully delivers

up the vibrations of which it is the vehicle. The second sound board transfers the motion to the air, carving it and chasing it into forms so transcendently complicated that confusion alone could be anticipated from the shock and jostle of the sonorous waves. But the marvelous human ear accepts every feature of the motion, and all the strife and struggle and confusion melt finally into music upon the brain.

My reason for introducing the above quotation at this time is that there are two well-defined schools or classes of makers: those who believe everything depends scale and string quality with very little importance attached to the sound board (with seemingly good authority back of their attitude and support by such illustrious men of the piano world as Alfred Dolge); and those who contend that the sounding board is the supreme determinant of tone. A combination of the two classes is found in one maker who has succeeded in producing the most wonderfully toned pianos in existence today.

The above “deal rod” test proves conclusively that the vibrations travel in every direction through the sound board, else how could they come from many positions in the bridge, through the rod and up into the second amplifier (transducer – ed.), in the form of violin, guitar or harp? The very nature of vibration itself is an important consideration to the tuner-repairman, and upon a true understanding of the foregoing and the following facts depend the “do’s and don’ts” of the directions which are given in another part of this treatise, “Diagnosis of Trouble.”

A misunderstanding or a misapplication of a principle or law may be at the bottom of many disagreements in regard to things scientific, and because of this I ask a bit of indulgence from those who might wish to dive promptly into the heart of repairs.

In Pianos and Their Makers, Alfred Dolge concludes that, because one Seigfried Hansing shows the fallacy of the “wave

theory” in wood, the sound board does not give off sounds. It is my intention in the next section to show that Mr. Hansing was right in one respect but wrong in another which vitally determines our procedure in repairing the board, even making possible an understanding of this mysterious thing called “vibration.’ Oscar Paul’s belief that the sounding board was the soul of the piano was not far amiss. The very “empiric experiments” employed by Mr. Dolge and his co-workers in the famous old Mathushek factory actually prove the point, as I shall show, their opinions to the contrary.

Just as a chain is no stronger than its weakest link, so the piano is no better than its worst element. Every item has its direct and indirect influence upon every other. Waves such as travel in the air and upon the water are not found in wood, but there are amazing similarities between the two. Upon these similarities depend that wonderful factor “amplification,” which will also be explained in detail in “Diagnosis of Trouble” with its practical significance outlined.

Let us suppose, for the purpose of illustration, that we could have a piano with perfect strings and an ideal scale – which would include the best choice of action, placed to strike at a point to quench the objectionable partials, nicely explained in Mr. Antunes’ article Voicing (in the Tuners’ Journal June, July and August 1925), and with such voicing as only a man of his understanding could do. But if the sound board of this piano lacked excellence of workmanship and material the greater portion of these valuable elements would be lost, because the lack of amplification in such an inferior board could not be compensated by any other quality of excellence.

On the other hand, if a piano had strings of unequal elasticity, improper reserve ductility, unequal size within a given length, and consequently incapable of being purely tuned because of irregular

nodal points which often set up beats within the single string, no manner of excellence in the sounding board could offset such a lack. Such a piano would practically be bereft of overtones, which Helmholtz determined were a large part of the tonal timbre or “klangtint” of the tone of the piano.

A poor sounding board is so irresponsive, “stiff” and insensitive, we might say, that it does not properly amplify either pianissimos or overtones. The only reason for these conditions is that cheap makers do not know how to produce mechanically correct instruments, while the wise ones know the vast importance of little things.

Instalment 2

November 1925 pp. 279-281

Vibration

Its Part in Amplification

The nature of vibration and its aid in determining the exact location and extent of ills existing in the sound board will be my next topic. The task of selecting from an accumulation of material better suited to be set forth in a volume only such things as befit the purpose and scope of a small treatise such as this is not at all easy. I have tried, however, to arrange the material so as to make the steps taken appear almost self-evident, without the need always of quoting from or referring to authors.

In order to understand the nature of vibration it is necessary to consider the molecular theory.

All matter is said to be composed of molecules, particles so small that the most powerful microscope cannot make them visible. Each of these is still further subdivided into atoms, which are in turn made up of electrons, with a nucleus of electrons of one type of charge, positive or negative, around which circle electrons of the opposite charge. Electricity is thus given credit for being the fundamental

oneness at the bottom of the universe, the secret of which is buried in the heart of matter itself so deeply that man can never hope to discover it. The mass of an electron is 1/1845 of that of the hydrogen atom which is the lightest known. (Practical Physics, Black and Davis, page 305.)

The grouping of molecules, the density, and the molecular attraction within solids, varies so greatly that the amount of strength or resistance to outside influences differs in various substances to such an extent that, aside from actual differences in physical content,, there are notable variations in structure in different woods, some of which are entirely unfit for use in musical instruments. “In regard to sound and the medium through which it passes, four distinct things are to be borne in mind – intensity, velocity, elasticity, and density.” Sound, Tyndall, page 74.

Air is known to be made up of so many particles per thimbleful that man could not count them in a lifetime. To express the number of these particles held by atmospheric pressure against the sound board of a piano would require a string of figures from NY to Chicago. These particles are in a high state of agitation, or commotion, all the time. Air has one quality common to all gases, unlimited expansion. This quality makes it the most elastic of familiar substances and the most sensitive to agitation, though not the best adapted to the speedy transmission of sound, as will appear from statements of facts ascertained by scientific experiments soon to follow:

Scientific education should teach us to see the invisible as well as the visible in nature, to picture with the vision of the mind those operations which entirely elude the bodily vision; to look at the very atoms of matter in motion and at rest, and to follow them forth, without ever once losing sight of them, into the world of the senses, and see them there integrating themselves in natural phenomena. With regard to the point now under consideration, we must endeavor to form a

definite image of a wave sound. We ought to see mentally the air-particles when urged outward by the explosion of a balloon crowding closely together; but immediately behind this condensation we ought to see the particles separated more widely apart. We must, in short, be able to seize the conception that a sonorous wave consists of two portions, in one of which the air is more dense, and in the other of which the air is less dense than usual. A condensation and a rarefaction, then, are the two constituents of a wave of sound. – Tyndall Sound, pp. 35-36.

Condensations and rarefactions as just referred to have their characteristic differences depending upon the medium through which the vibration or shock is to travel. With a few exceptions, which are due to restricted elasticity, the greater the density of the matter through which a sound is to travel, the smaller is the amplitude of the wave, but the more swiftly will the impulse between particles be imparted, and the more velocity will the sound have as is noted by comparing the following data:

Velocity of sound in air… 1090 + feet per second

Velocity of sound in water … 4714 + feet per second

Velocity of sound in fir… 15,218 feet per second

Velocity of sound in steel… 16,023 feet per second

These figures would have to be revised for any great variations in temperature, compression or affected densities, and therefore serve only roughly. There are variations in elasticity that greatly affect the velocity of sound in matter. It is due to the solidity of molecular constituency of fir combined with its wonderful elasticity that it is so satisfactory a material for the amplification of sound in pianos.

A common error of those who have considered the nature of the transmission of sound through the sound board has been to expect to find the board divided up into undulations of perceptible size. Upon such a misconception hung the announcement by Seigfried Hansing that

there were no “waves of sound” within the sound board. This also led to the assertion that it was ‘tremors” in the board which excited the air with transmitted shocks which were carried to the ear drum, and thence to the nerve centers of the brain, where the mind recognized tones – music. The same failure to learn the exact limitations of the thing called vibration brought Mathushek and Moser to the conclusion that there were no transverse waves in the sound board. The gluing of two sound boards together with the grain in one running across the grain in the other was the specific example that convinced them.

The motion of the sonorous wave must not be confounded with the motion of the particles which at any moment form the wave. During the passage of the wave every particle concerned in its transmission makes only a small excursion to and fro.

The length of this excursion is called the amplitude of the vibration. – Tyndall, Sound, page 73.

The argument that the sound board does not give off sound is an exact parallel to the old war horse of debate: if a great tree were to fall in the forest out of the range of any ear, there would be no sound. Any of us can contradict, reverse and restate any fact, but often with a ludicrous inclusion of ideas just “refuted.”

If my wife says, “You are letting the cold air in,” and I correctly reply, “My dear, it is only the radiation of heat from your own body that gives you the sensation of cold air striking your body,” the essential facts have not been changed in any way.

We can likewise be captious in regard to the phenomena of sound. All intelligible definitions of sound include the idea of transmitted shocks impressing themselves upon the ear drum and there being translated into “noise” or “music,” determined by the origin of the shock.

In this connection there are so many considerations that it is impossible always

to appear perfectly logical. We are in the midst of a field of interrelated elements that are inseparable one from the other. To follow one element very far would take us away from others just as important, so we must return to the same facts under slightly varying phases or contact with those around it.

The limitations in our vision and perception, through the nervous system of our bodies are responsible for our capacities for enjoyment. If we could see the horrible organisms we daily consume – microbes, bacteria, etc. – our lives would be miserable. If we could feel every shock of the strings of the piano, that is, if our perception-limit were as fine as one-thousandth part of a second instead of about one-twentieth, the individual shocks would not blend into musical tones, except such pitches as are of proportionately higher frequencies. Our whole realm of music would be upset. That the limit of human perception is about one-twentieth of a second is easily demonstrable by anyone who cares to go to the trouble.

To prove this point to my own satisfaction, I made three small and light reproducers, so that their weight would not cause the disk to drag, and tried them at various distances from each other in the same groove on the record. By using specially constructed points I could cause them to approach as closely as one-half inch of each other. By computing the velocity of the revolving portion of the groove between the points, I found that the difference in the instant of attack when the time limit was as small as one-fortieth of a second was less than is observable in ensemble at most concerts, while a variation of even as wide as one-sixteenth of a second was not at all offensive. The truth is that the error in delivery found in a very large chorus ensemble is often as great as one-seventh of a second.

The importance of the truth just stated is greater than it appears at first. That our limit of perception is low in comparison

with the tremendously swift travel of impulses through matter is an auspicious guard or mother of the whole phenomena of amplification. The very spaces that are known to exist between the molecules of matter permit them to bump against one another in multiple fashion so that the molecules transmit many rates of frequency at the same time.

This is not nearly so marvelous in the sound board as is the transference taking place within the needle of the phonograph. Here at the same instance are imparted through the same molecules, by means of infinitely varied parabolas, ellipses, circles and zigzags, all within millionths of an inch of cubic area (if only some way to record the same could be devised!), textures, pitches and forces with the current noises of the entire orchestra, then on to the diaphragm, where a similar transference of motion, in less than one-thousandth of a second, is spread to all the molecules of the mica, which in turn give their peculiar motions to the particles of air. This, as before stated, is so infinitely elastic as to expand indefinitely and yield and rebound to every slight impulse; and there the motion is conducted in one direction through an ever-widening “hallway” with shocks very many times multiplied, both by reflection and molecular group-shooting to the outside, where our ears are literally bombarded with the accumulated and augmented “sounds-to-be” at the threshold of intelligence. The entire transference of action here described takes less than one-five-hundredth of a second to complete. Our poor gray matter is moulded by at least twenty-five repetitions of the process before we awake to the reality, which is no disgrace.

Instalment 3

December 1925 pp. 335-337

More About Amplification

Its part in tone

In the previous section we considered the molecular theory, and how it enables us to understand why and what is amplification. We also found out that it is easy to be led astray “scientifically” unless we are very careful to base all conclusions on facts.

In this section we shall go more deeply into the actions of the molecules of the board when amplification takes place, using the imagination in keeping with known facts, to let the mind’s eye see an endless variety of possibilities within the compass of a space almost too small to measure.

In the same manner that the distinctive movements within the particles of the needle and its diaphragm characterize the sounds given off, so do the molecules of the sounding board give off faithful transcriptions of the rates of vibration and peculiar regularities or irregularities of the elements concerned in their production, namely, string texture, age, elasticity, the conformity of striking points to law, the susceptibility of the bridge to transmission, the board’s homogeneity or its lack and its elasticity, uniform or irregular.

The ideal combination of these and all other essentials constitutes “fine” tone. These movements of the small particles of the sound board surge with such speed that for every impulse delivered by the fastest vibrating string in the piano (about 4,000 per second) the shock reaches every molecule in the instrument. The present sizes of the sounding boards that have proved most satisfactory follow the line of average wave-length from the greatest number of positions upon the bridge, which are the origin of impulses. The law of reinforcement by regularly repeated impulses, which includes also the manifestations of interference when distance does not accommodate well-timed reflections of vibrations, comes powerfully into play in this instance – making beautiful volume in certain parts and smothered effects in other parts of

the same piano harp, if the relationships of constructural detail are not well disposed.

A well-known illustration of the power of repeated impulses is that of a dog trotting over a great bridge and setting it into violent motion. A recent demonstration of this principle ended disastrously when a dance hall in Carolina (South?) collapsed under the continuous rhythmical shocks delivered by the major part of the dancers doing the “Charleston” undulation in unison.

Consider now that the separate pieces of the sounding board are assembled with the grain running about parallel with the treble bridge, from corner to corner of the piano in the upright, from “point” or rear left to high treble portion in the grand. This design is of great significance. The best toned pianos always use this form and will always do so for the reasons I shall now state.

The speed of transmission of the shock along the grain was given as six times that across the rings which would be through the thickness of the board. (from three-eighths inch in the treble to as thin as one-quarter inch in the bass, according to Alfred Dolge), and so not to be considered, while three times the velocity along the rings, which would be across the pieces, that is, across the grain. As the distance from the center of the bridge to the edge of the piano straight across the grain (in the widest part) is about one-half of that from the same point on the bridge to the corner, and since there is a quantity of straight-grained wood in the ribs so closely assembled to the board, through the glue man’s art, that it is really an integral part with many of their molecules held firmly against the molecules of the main part of the board, and as the ribs are about twice as thick as the thickest part of the sound board, there are enough fibers within the ribs to be equivalent to from thirty to fifty percent of the total volume in the sound board. The travel from bridge to

edge and return is fairly equalized in velocity with that to the ends and return. The board narrows almost to the same degree that the wave length is shortened through the higher frequencies of the tones ascending, while the width is increased greatly toward the end of the slower rate tones which have the greater wave lengths. The problem is such as never to permit the perfect solution.

In every case, amplification (the making of full volume) is multiplied transference of action, enlargement of the field of applied forces or motions, increased volume of affected areas of agitated, transmitting or reflecting substance.

The transmission of sound through a solid depends on the manner in which the molecules of the solid are arranged. If the body be homogeneous and without structure, sound is transmitted through it equally well in all directions. But this is not the case when the body whether inorganic like a crystal or organic like a tree, possesses definite structure. – Sound, Tyndall, p. 69.

The uniformity of arrangement in structure along the fiber of fir wood accounts for the greater speed of the traveling vibration, while the little paddings of resin between fibers, and the layers of resin between the rings of growth contribute largely to the great elasticity of the wood, though retarding the vibration transference across the grain. Let us trace the actual happenings within the board as amplification takes place. We have a “rude shock” delivered through the string to a rather stiff and unresponsive bridge, which rests upon an elastic foundation, the sound board. Its molecules are violently agitated and the impulse is carried to the edges of the board, where the firmly anchored edges constitute a wall from which the shock among the particles is reflected back over the path of its arrival, returning to the center of agitation at the same instant that the second impulse starts. The force of the first is added to the second and the augmented impulse again goes to the

edges of the board where it is again reflected with small loss, again arriving at the place of origin as another impulse is given or added. This same process is repeated as often as the frequency of the vibration of the string that is struck. In a perfectly proportioned board there would be but an imperceptible variation from the exact rate of each tone with reference to its reflected reinforcements. These built up amplitudes actually cause the board to heave and sway, motions that can easily be felt by putting the hand against the board while someone is playing. These very heavings of the board proclaim the presence of foreign matters, or loosened ribs or edges of the sounding board. Any thing that hinders the free movement of any section of the board restrains or destroys the normal amplitudes that should be developed at such points in the board. Because of this fact there are some insistent laws governing the methods permissible in the repair of a sounding board, which will be stated later on.

Music is primarily composed of mathematical and symmetrical tone lines, wave length combinations that impart impressions in their own likeness upon the receptive mind. We should not be surprised now to learn that investigations by Chladni revealed the fact that all vibrating bodies assume within themselves various symmetrical designs in the distribution over their surfaces of the areas of greater and lesser agitation, depending upon the source s of excitement and the places of interference. This law holds in wondrously complicated form in the diaphragm of the reproducing machines and in the sounding board of the piano.

In this fact lie the reasons for the prohibition of the use of shims and the specific use of screws, which will be dealt with in the next section.

Instalment 4

February 1926 pp. 416-419

Reflections; Symmetrical Lines of Comparative Quiet – Defining Figures;

Interference; Diagnosis of Trouble

To gain a better impression of the relative importance of this subject, it will prove profitable to take a brief inventory of the matter.

Music is one of the greatest forces in modern life. The piano is the most popular instrument of the “play-it-yourself” type. It is the one the foundational requirement in many courses of musical education, one to three years of piano study being required for graduation in other instrumental courses.

In all musical instruments there is some means of enlargement or amplification of tone, such as a sounding board, a resonator or an expansive “hallway” for multiplying the reflected vibrations and condensing them all in one direction. The audion vacuum tube has revolutionized amplification in some instruments, though it is only an example which bears out the statement that too much importance cannot be attached to the problem of true and rich development of the tones of musical instruments, and of pianos in particular.

Due to the influence of climate, of which changes in humidity play so vastly important a part, sounding boards are often much changed from their original dispositions. Men of wide experience recognize that pulling apart of fiber, looseness of ribs on the sounding board, loosened bridges, etc., are grave troubles and prevalent to a sufficient extent to demand considerable attention.

This series of articles has been devoted so far to the laws underlying the construction of the sounding board, so that the conclusions reached may come to the reader naturally.

A mastery of these principles by the piano mechanic will lead to far greater efficiency, will materially increase his

earning capacity and prestige, and besides will remove one of the most evasive causes of “dissatisfaction” with his tuning, as many s good tuning has been wasted on a piano in which the need of sounding board work was undetected by the unsuspecting tuner, and once neglected the tuning was usually lost to him for all future time. I know that in my own experience I could not succeed without this knowledge. A fair part of my earnings comes through the correction of faults found in some part of the sound amplifying apparatus of the piano. The present article deals with knowing how to find the trouble, and should be given undivided attention.

Usually much confusion is attached to the words “vibration,” “tremor” and “wave” and for perfect clearness we must consider a limited use of these words and their absolute relationships.

A “vibration” is started with an original impulse which in the very nature of the entire instrumental ensemble would not make enough headway against such overwhelming obstacles as the inertia, strength and relative immensity of the board-bridge assembly to produce a “tremor” until perhaps five or ten repetitions had built sufficient amplitude to be felt. The “wave” is the outward surge of the impulse; it embraces every particle of matter affected till the arrival of the next impulse, which may coincide with or overlap in varying degrees the reflection of the first or immediately preceding impulse, single, double, triple, etc., depending on the frequency, or pitch, of the origin of the impulse. Vibrations and tremors are not coincidental except in the lowest tones, where elements are great and natural periods are slow. Tremors are the results of vibrations, a sort of manifestation of vibration translated into areas, but they may have periods of much slower frequency than the vibrations inducing them, as I expect to demonstrate under a different title at a later writing.

By way of emphasizing the fact that nothing is too small to be considered in insuring the integrity of the sounding board of the piano, I quote from Alfred Daniell’s text book, Principles of Physics, chapter XIV, page 455:

When a beam of light or radiant heat falls upon a body capable of absorbing heat, that body becomes warmed and expands. A flash of light produces an instantaneous expansion, which immediately dies away. An intermittent beam produces a succession of expansions and contractions; in other words, the surface of the body vibrates. The amplitude of its movement may, with beams of light of moderate intensity, exceed the ten-millionth part of a centimeter. Lord Raleigh has shown that this amplitude is sufficient for the production of sound; and the power of converting the energy of an intermittent beam of light or radiant heat into that of a sound has been shown by Prof. Graham Bell to belong to all matter, with a few doubtful exceptions.

If an intermittent beam be focused upon a mass of lampblack, at each flash of light it becomes warm, and the air within it, is dilated; if it be contained in a test tube, the open end of which, is connected with the ear by an India rubber tube, as the successive flashes produce successive dilations and pulses in the air, these pulses are perceived by the ear as sound; if the lampblack be contained within a resonator, the frequency of whose natural vibration is equal to that of the frequency of the successive flashes, the resonator emits a loud sound, audible at a glance.

I quote one more point of great interest from the same text, page 466:

The movements of the drum of the ear are astoundingly small. The greatest displacement seems to be about 0.1 mm. or 1/250 of an inch. A sound produced by an F# (181) pipe under an air pressure of 40 mm. of water can be distinctly heard at a distance of 115 meters (127 yards). Topler and Boltzman calculated that at such a distance the movements of the air must be reduced to .00004 mm.; but those of the more massive drum, with its appendages, cannot be more than .000,001 mm., or the twenty-five-millionth part of an inch – an oscillation so minute as to be beyond direct microscopic observation.

In view of the many facts herein and previously given, it can easily be imagined that the sounding board of the piano vibrates in almost infinitely varied forms. Every tone produces its individual difference in distribution of agitation, having high and low points of excitation, which are greatest in amplitude where the appositional outward surges and the returning reflections of the previous vibration meet. All combination of tones, such as chords, arpeggios and scales, describe their own ever-varying designs of peculiar disturbance.

The amplitudes of these vibrations are determined by the force of the impact of the hammer against the strings, and the wave length is determined by frequency. In many parts of the same board opposing influences may arrive at the same instant. The result of their combined energies is the production of conflicting “waves” inn the sounding board movement, constituting the condition known as “interference,” which is present to some extent in even the best constructed pianos, and in badly constructed pianos brings about a comparatively great nullification of amplification. The extent to which a maker succeeds in constructing a board which permits a great preponderance of favorable, appositional generations of reflections coalescing with arriving impulses spells his success in producing fine tonal volume, other elements having due attention.

For all these reasons, every portion of the sound board, except the edges where support is given to the arch, must be able to respond freely in the transmission of impulses.

To get some idea of the intricacy of designs possible to be generated by the transmission of sound waves in the sounding board of the piano see the copies of Chladni’s Figures, produced by agitating square plates, some of them held at their centers, and touched at various points about their boundaries,

thus creating various lines of interference, whose “nodes” and “internodes” of commotion have arranged the sand to form the designs. (From Tyndall, Sound, pp. 171-173.)

Effects of combinations of various frequencies are simply shown in diagrams from Spinney:

<drawings of various wave forms from Spinney Text Book of Physics, 1925 edition. Pp. 476-477>

The outcome of all these manifestations peculiar to the sound board is that we are able to recognize ailments by their symptoms the majority of which I have outlined as follows:

Short loosened places along the ribs in the central portions and in the high treble, short loosened places in the top of the board, and long cracks not wide enough to be seen readily unless the eye be directed to them assert their presence by queer little wheezes and sometimes by a “tingle” in the tone that is also accompanied by a notable weakness. People with pianos so affected often say, “I wish you would take that pin out of the piano. See how funny it sounds!” Do not confuse this with “sympathetic vibration” or “tuners’ ghosts,” and remember accompanied by a notable weakness.

A bridge that has come loose usually rattles, though sometimes its call to you is, “I’m a gourd,” or “I’m a cellar door” – hollow like, you know! Badly parted ribs, very long loose edges, loosened corners and completely loosened lower bass bridges assert themselves by rattles, except when too badly warped, and then there is an easily discernible slumpy, mumpy, dumpy, tubby sort of tone.

There should now be no doubt of the need of making the repairs as nearly “low loss” as possible. Shims inserted into cracks in the board itself, unless it is easy to see that the board was not properly seasoned in the first place, are hardly advisable,

because of the possibility of some period of prolonged excessive humidity swelling the board enough literally to crush out the elasticity of certain weaker portions of the board. If cracks exceed 1/16th of an inch in width, as is sometimes the case, shims are to be used in the board itself, otherwise they are filled with a composition which will be described later. Shims never should be inserted between the ribs and the board on account of the extra bracing they exert. If the gluing of shims is perfectly done they actually constitute an architectural restriction to elasticity along that particular rib, and if not perfectly done they act as a positive damper upon transmission of the tone in that section. Screws should be as small as possible to insure perfect holding and the rib=board connection should be triple-drilled to avoid creating “islands of increased density” and thus rendering their location a dead obstruction to the vibrations perhaps from some much used section of the instrument.

The strongest interval to use to bring out any defect in amplification is the ”perfect fifth.”

Instalment 5

March 1926 pp. 462-464

Next to the choice of materials, and design and workmanship, the gluing and preserving of the sounding board of the piano are of almost incalculable importance. Barring undue exposure, abuse and accident, the secret of durability lies in the excellence of the gluing and the coating of the shellac and varnish. In the preceding sections the necessity of fine material and workmanship to produce a board capable of correct amplification was made clear. It is now my purpose to outline a manner of making speedy, efficient, complete repairs which restore strength and quality to boards that have lost these qualities, and to prevent the reappearance of troubles.

The method I use is not entirely of my own devising. The principles developed in this series were given to me in brief form by one Albert Williams, a piano and pipe organ expert with whom I made a providential friendship about fifteen years ago. He was a piano rebuilder who knew the value of indirect advertising, and was a past master in the art of soliciting work, with the ability to convince as to a piano’s needs, and with a knack that enabled the customer to forget about the “cost” of the proposed repairs in consideration of the ideal condition into which he was suggesting that the owner “desired” him to put the instrument. Mr. Williams was a psychologist who left the conviction with every one for whom he tuned that he loved his work so much that he could not leave anything partly finished, and he compelled notice of the extras he put into his work as “good measure,” not boastfully, but tactfully. To him I owe more than I ever shall have the opportunity to repay, since he came to an untimely death in Clarksville, Tennessee, in 1914, in a church where he was installing one of his own pipe organ blowers.

He was also one of those men who believe that the sounding board of the piano could still be improved. He told me of a board he had constructed upon scientific principles, with dimensions, shape and size best suited to accommodate the velocities and rates of tone vibrations, the boundary of which board he said was oval (His board was left in storage in Topeka Kas., in 1909, and was not patented because of immature plans concerning a factory he intended to build for the manufacture of his own boards and blowers.) I mention this merely to indicate the nature of the man from whom I got my inspiration to improve the amplifying qualities of every piano I find in need of such attention.

During a period of fifteen years I have worked in the same territory, with opportunity to observe closely a great number of pianos and to know the conditions under which practically all of

them were kept. Those pianos which received the greatest care in their manufacture held and do hold tuning best, stand up under the unavoidable differences in humidity and temperature and develop the fewest troubles in sound amplifying apparatus. Conversely, the products of haste and commercialism pure and simple sometimes come unglued before they reach their first “consumer.” One exception I wish to note: no excellence in material and workmanship can withstand erosion, which some owners actually promote under their own roofs. Moisture plus freezing causes the finish to flake, break minutely, crack, then peel, and leaves future attacks of the same process freedom to dislodge glue joints, and finally to sever all severable parts. If the surface of the finished board feels rough to the touch, be sure that the piano has been subjected to alternating periods of warm dampness and freezing spells. For these reasons I feel that a few words about glue and varnish may be in order.

Much misunderstanding prevails in regard to the nature and use of “glue.” Many mechanics seem to think that “lots of hot glue” boiled over and over again and again in the same old dirty pot is “the dope.” That glue has great strength is another misconception. If strength were an inherent quality of glue itself it would not be so notably true that the best cabinet makers and piano men leave as little as possible in a perfectly made joint.

Glue is a gelatinous substance extracted from the skins, scales, hides, bones and connective tissues of animals and fish. Its molecules are very fine and of a very low rate of vibration, having a high degree of intermolecular attraction, but a still greater affinity for other materials, especially for porous substances such as leather, cloth and wood. The stickiness of glue is due this fineness of consistency plus its molecular attraction within itself. Its aptness for holding other things together is the affinity for other substances, scientifically called

“adhesiveness.” Too much boiling can destroy to a great extent this prized quality in glue. The report of O. Linder and E.C. Frost before the 1914 meeting of the American Society for Testing of Materials pointed out that “overheated glue is found to be weakened forty per cent to fifty per cent.”

The Madgeburg hemisphere test, performed in 1650 before the German emperor by Otto von Guercke, illustrates the next point I wish to make. If we completely exclude the air from between the joints with glue we are practically utilizing the marvelous force of atmospheric pressure to hold the parts together. It required sixteen large horses to pull apart these twenty-two inch “hemispheres,” perfectly fitted together and then pumped free of internal air to create as near a vacuum as was then possible. (See Practical Physics, Black & Davis, pp. 101-102.)

In this one element lies the reason for having the glue hot. It will find its way into the pores of the wood and make an absolutely air-tight joint. In the same report of Linder and Frost it was brought out that blocks of wood glued and tested for the strength of glue required from 1,100 to 1,950 pounds to the square inch to pull apart. These blocks were clamped together after the manner of cabinet making, and therefore were glued by means of what might be called a hair line joint. In all successful sounding board gluing every particle of glue that will squeeze out from between rib and board, bridge and board, or edge of board and frame must be forced out, so as to permit the actual touching of the molecules of the two parts to be glued together. The greatest care must be exercised to have the pressure uniform throughout the length of the parts being glued.

Scientists consider resin, the principal ingredient always found in varnish, nature’s master stroke in preserving the fiber in vegetation, especially in mountain

growing trees, where it is found in greatest quantities. Wood properly treated has wonderful durability, and the necessity of preserving the integrity of the sounding board of the piano needs no proof at this time. But there are many types and qualities of varnish, each for its own purpose. A few vital hints in connection with the use of varnish in the sounding board work should be sufficient.

Keep unused portions of varnish away from the air as much as possible. Keep brushes perfectly clean, and brush out the varnish rapidly from spare dipping as thinly as can be smoothly done in each coat to be used. Plenty of time must be allowed between coats. This will give the finished product an elasticity of surface it cannot have in any other way, will insure against cracking and consequently will prove impervious to moisture.

Granting that the ideal repair job can be done best in a shop equipped with every convenience, still probably two-thirds of piano owners are living too nearly to the limit of their allowances (?) ever to afford, or to feel they can afford, to send their pianos to shops. Of those who might afford to do so a great many will decide against it. An efficient, sure and speedy method for the accommodation of this class, and especially valuable to the independent man who has no shop, will be shown later.

Before launching upon this subject, I will say that I have found boards come unglued again in pianos that have been sent back to the factories to have their sounding boards repaired, probably because of the fact that conditions are overwhelming against the durability of the methods employed. For the benefit of those who may have a healthy fear of screws in the soundboard, let me mention a piano which had two hundred screws distributed over the entire area of the board. Its tone was as full and clear as any piano of similar quality of material, design and workmanship I have seen. I have

actually found a few pianos in which, after the sounding boards gave way and the repairs were made, the tone carried better than when new. Seemingly there is somewhat of a situation here like to that found in some cars – they ride better with a full load. Many have been the times that my patrons, unbidden, have said: “Why, that piano sounds better than it did when we bought it, new,” and I refer to pianos whose sounding boards I have repaired.

Now comes the time that I will describe my method of making repairs, and the tools used.

Instalment 6

April 1926, pp. 510-513

When first considering the presentation of the method which I have found best for the repairing of piano sounding boards I thought of giving mere outlines or details of the work itself. It then occurred to me that a fair treatment of the principles underlying the purpose and function of the board would be of lasting value to men whose opportunities had not hitherto placed such knowledge in their possession, and the editor of The Journal agreed with me that the matter could be better handled in a series of articles.

If any man would reap benefit from knowledge, he must use it. To use it rightly he must fully understanding it, and he must literally be full of his subject. Thousands of sounding boards are awaiting the expert attentions of skilled hands.

Mere discovery is the first step. Tactful breaking of the news to the owner, and effective appeal to his or her sense of need and pride in the “excellence of condition of his or her own property” – an idea that appeals to all minds, in that whatever they have they want it to be all right – is a leverage that can usually be depended upon to bring a decision for the repairs. Little need be said to the customer about the method to be used if a

right attitude is assumed in regard to the need and the certainty of an ideal condition of the finished repairs. The cost is usually better based on principle that it is the desire of the tuner to deliver great value with fairness, but that on account of the difficulties involved in the task and the amount of work and time needed, the job will cost so many dollars, which is less than transportation of the piano to the factory and return, to say nothing of the actual cost of the repair if the piano were sent to the factory. The method of persuasion will vary to suit the individual and the occasion, of course, but I have found the price named is usually a shock to the customer, until a comparison of alternatives is made, which leads to a decision in favor of the repairs “at home” and “now”! On the other hand, it would be obviously false tactics to persuade a generous, wealthy, broad-minded patron to have his repair made the “cheaper way.” Efficiency, and not economy, is his chief consideration.

Nothing can take the place of the ability to present a proposition convincingly, appealingly, persuasively and with no appearance of concern except to serve the patron in the finest possible way. Such bluntness as, “Madam, your piano’s got a busted sounding board. I’ll have to charge you ____ dollars for fixing it,” rightly brings the reply, “Mercy!” or some such ejaculation, and a decision to “see about it.” In brief, an explanation of the purpose, importance, and the function of the sounding board, together with an appeal for the opportunity to restore the tone to the piano, with a quiet assertion that tuning without this work is wasted, worthless, and a risk to “my reputation which I cannot afford,” will in most cases bring the authorization to “put it in shape.”

No two repair jobs in sounding boards are exactly alike. For this reason a man must exercise judgment. The facts concerning elasticity, density, intensity and velocity, which have been presented in this series,

require that repairs be made in a manner to affect these qualities as little as possible, which is best done as herein outlined. Variations from this set of requirements are apt to produce “rumbles,” “distorted amplifications,” unbalanced designs in the travels of waves and their reflections manifested in queer “raspy,” pinched or dwarfed tones, in certain parts of an instrument that may be fair in other sections.

The tools needed are a brace and bits one-half inch, three-eighths of an inch and on-quarter of an inch; three screw drivers, one large, one small and one with a long bit; if possible, two Yankee drills one a two-handed operated ratchet, or crank for heavier work, the other of the spring-ratchet type for light or delicate work, enabling one to leave the different sized ready for instant use in the different depths, as drilled; prying tools, either hickory or oak slats pared thin enough to be convenient or tire tools made of discarded broken car springs; a thin spatula, or pliable knife, for determining all loose places, also for use as a glue knife; one reamer, or combination tool including reamer, and other bits of equipment; one gross of half-inch No. 7 or No. 6 round headed screws in blued steel, one gross of three-quarter inch No. 8 and one gross of one inch No. 8 screws of the same kind, with an assortment of longer and larger screws for emergencies; about fifty wedges of either hickory or oak, from ten to fourteen inches long, tapered from less than one-half inch thick at the small end to one inch at the larger end, not over three-quarters of an inch wide; and other tuning and repair kit paraphernalia. For ease in repairing the top of the board a piece of strap steel, prepared as in diagram C, enables one to draw the parts together without bothering the tension of the strings.

Procedure: wash the board thoroughly. Find every loosened place, and mark each end. Mark a spot for the screw in the exact center of the central rib that is loose.

Group the locations for the screws in the rest of the board as symmetrically as possible, that is, put about the same weight of screws on each side of the center. It would take a great deal of writing to explain fully why I advocate this, but the truth stated in earlier articles should make it seem advisable to arrange the screws carefully, to respect the balance in the periods of vibration. Referring to diagrams A and B the manner in which the screws are to be used will be seen. The wedges and prying tools are always to be used in bringing the parts together before the screws are inserted. In the drawings will be found details worth noting.

One caution: when a cupped place is found in the board never pry it back to the rib. Brace it on the strung side of the board and then pry (avoiding any strain shear-wise) the rib back to the board. The way I have found most effective to get the glue well under the ribs is not to force the knife completely under, but to slide the edge of the knife repeatedly through the glue to be worked under. A small portion can be caught with each stroke and worked till the oozing fluid appears on the opposite side of the rib. This avoids bruising the wood of the board or enlarging separated parts.

If the rib and board be forced tightly together, a hole need not be more than started into the board with a drill of only one-sixteenth inch size, Caution must always be exercised never to overturn the screw. When properly settled into position a small screw may possess wonderful power to hold; if overturned ever so little, it is worse than useless.

To prevent drilling beyond desired depths, an assortment of spools cut to fit on the drill bits and to engage the chuck at the instant proper depth is reached will save time in measurements, and will insure uniform accuracy.

It will sometimes be found necessary to place a screw back of a stanchion, which

can be done through a hole made by a brace and a three-fourths inch bit. This will call for a “screw holder,” and one long bit of the size 11/64, which can be made by the tuner. A pedal prop, a file, and a bit of patience turn the trick. The threaded end is to be filed for cutting, and the shoulder end for chuck. Usually, however, it is found possible to insert screws from the opposite side of the board, that is, on the strung side, back of the stanchions, in which case the hole in the board is to be as large as the screw, and the hole in the rib very small. Flat-headed screws and sound board buttons are always used on the strung side.

The method described by Nels C. Boe, in the January, 1926, issue of The Journal, page 402, under the title Loose Ribs, is to be employed wherever the loose places happen to be in the clear of the plate.*

When cracks are no wider than about one-sixteenth of an inch the most effective manner of repair is to use the composition here described:

Work thoroughly one part of glue into three parts of yellow wood filler and into this mix thoroughly two parts of high grade varnish, into which all the powdered resin it will absorb has been stirred. After blending this mixture until it looks like pale, thick molasses if it is too thin to stand easily upon a knife blade work in still more of the powdered resin. The cracks should be completely filled with this composition. It takes almost three days for it to dry sufficiently to stand up properly, and it is often necessary to give a second application. It will take more than one effort to prepare this composition as it should be, since the exact consistency of both the filler and the glue have so much to do with the balance between the proportionate amounts.

If there are strings in the center of the piano that possess a jingle, say middle G, D and E with accompanying black key tones, it is probably due to a settled board, one in which too much of the arch

has been lost. In such pianos the tension must be let off while the repairs are in progress, and it is advisable to give the entire board, both sides, a good bath in denatured alcohol while some pressure is exerted from the rib side of the sounding board. In all this work the judgment of the mechanic is paramount. In any case the very center of the board must not be lifted more than one-half inch, with correspondingly less raising outwardly from the center in every direction to about one foot away from the center, while in most pianos it will be found that three-eighths of an inch lift, sustained by wedges upon the ribs so placed as to permit the repairs described herein, will prove sufficient. There are pianos that will not need more than a good one-eighth of an inch lift. The surface of the varnish of the board is presumably very porous – I have never found a sunken board in which this was not the case – and for this reason the alcohol will penetrate within, dissolving the shellac originally used, as well as the natural content of resin. This will permit the necessary molecular readjustment, and favor permanence of the new form, if proper care is exercised in the coats of shellac and varnish following the repairs. The strings can be tied near their middle in groups of six, nine or twelve, without unhitching them, to make room to reach the board easily. There is little hope for the board that was made with too slight an arch, as is sometimes the case. I have a remedy, but I hesitate to pass it on.

With the purpose of the parts clearly in mind, and the nature of the sounding board so well understood, I believe that matters can be trusted to the ingenuity of the individual.

The greatest difficulty that faces the tuning profession is the attitude of the piano owner. Each man must solve his own problem of selling his service. Perhaps the patron’s attitude will be found to yield greatly to intelligent and intelligible appeals to his pride, sense and

desire. If there happen to be tuners who never fail to bring their prospects to the decision to have each and every item of repair made just as the tuners deem best at whatever price is asked, they either have a better set of patrons than I have found, or are much higher-powered salesmen than I happen to be.

Within the function of amplification exists the finest reason for the most frequent tunings of pianos. This I hope to be able to give in another article sometime.

THE END.

*(Here is what Mr. Boe had to say in answer to a query):

If the ribs are loose only in places there should be no difficulty in drawing the board and ribs together, and nearly if not entirely restoring the original “belly,” or at least the belly the board had before it was separated from the ribs. The board should be taken out only as a last resort, when everything else has been tried and has failed to bring about satisfactory results, because such a job involves problems entirely too big and too complicated, except for the best equipped repair shops.

In drawing the ribs and board together hot glue is preferable, and screws of the proper length and sounding board buttons are absolutely essential.

First clean off all the old glue as well as you possibly can, select screws of the proper length and size, that is, screws that are long enough to go through the buttons and board and well into the ribs but not through them. Also see that the holes drilled for the screws are of the right dimensions so as not to split the ribs or the buttons.

When everything is ready apply the glue, not too sparingly, to the ribs and the board, place the buttons on the front side of the board, insert the screws through the buttons and draw together. Use as many screws and buttons as are found necessary.