Saturday, June 28, 2014

What is sound?

The following is a translation into English of the chapter on instrument-making in our recently-published textbook in Spanish on the folk stringed instruments of Puerto Rico: Cuerdas de mi Tierra [Strings of my Land]


      Variations in air pressure against the eardrum, and
their subsequent interpretation by the brain, create the
experience of sound.
      The sounds that we recognize as musical are periodic
or regular variations. Those we recognize as noise are
random, or non-periodic.
      Musical sounds, like all other sounds, radiate outward
from their vibrating source in the form of energy waves
that travel through a medium such as air, water, or dense
      The simplest case is a single sound, called a "pure
tone." It is very rare to hear single, or "pure" tones in
the natural environment. Most sounds we hear are complex
tones, sounds made up of many tones happening together.
      When two or more different sound waves occur together
they interact: their pressure variations variously
reinforce and cancel each other to create a single, more
complex sound wave.  Our brain can still isolate the
individual simpler components of those complex sound waves
in order to recognize their source. Thus we can recognize,
without seeing, whether it was the sound of a pencil
falling on a carpet, or a spoon falling on a marble floor.
Also, our brain can decode the various components of the
sound in order to react appropriately: whether to ignore
the sound, whether to pay attention, whether to be alarmed,
whether to be soothed.

The Harmonic Series

      Every individual tone component of a composite
acoustic pressure wave has two distinguishing
characteristics: the frequency of the wave's rise-and-fall
and its amplitude or power. The frequency and amplitude of
the components of most ordinary sounds we hear--a door
shutting, water dripping from a spigot, someone sneezing--
are random.
     However, among all the sounds we can hear, there is an
extraordinary subset: those composed of frequencies that
line up in precisely numerical order. In these complex
sounds, the first component, usually the most predominant,
is the "fundamental" frequency; the next is twice the
frequency of the first; the next is three times the
frequency of the first; the next is four times the
frequency of the first; and so on until the frequencies
become too fast to perceive. Each of these components are
called "partials" or "harmonics."
      This ordered sequence is called the Harmonic Series.
Sounds whose component tones correspond to a Harmonic
Series are perceived as musical and are called musical
sounds. They sound like a musical note because its
fundamental provides us with its pitch and its ordered
series of accompanying partials, occurring at different
amplitudes, provides us with that tone's "color," or
recognizable distinctive sound.
      Sounds that are not ordered in this way, rather are
made up of random frequencies, we perceive as noise. It is
interesting to note that at one end of the spectrum, sounds
with random components like an explosion; a frying pan
falling to the floor; or a door slamming cause us alarm;
but sounds with components that are numerically ordered,
like the whistling of the wind; or the sound of a bird, or
the twang of a plucked string, bring us delight--and we
yearn to repeat the experience over and again, if we can.
It is as if we have an ancient, ingrained need for these
ordered sounds, sounds that are "musical" to our ears.

The stretched string 

Strings are truly magical: that nothing more than an stretched 
elastic fiber could produce so complex a series of hierarchically 
ordered tones has historically placed strings in the realm of 
extraordinary, mystical objects. The ancient Greeks, and later, 
the Early Church considered the harmonic content of a stretched 
string as nothing less than proof of the existence of God.    
         History has yielded up to us strings made of many different
materials: strings made of strips of animal hides, sinews
or intestines, nylon polymer and drawn metal wire. What
makes them all able to produce musical tones is that they
possess, to a high degree, three qualities: elasticity,
tensile strength and uniformity. This is what allows them
to behave as musical strings. In fact, how closely their
tone approaches a perfect Harmonic Series--and thus how
"musical" they sound--depends directly on the degree to
which they posses these three qualities. The history of the
string-making craft is marked by the quest to create ever
more uniform, ever more elastic and ever stronger strings.
      Strings made up of different materials differ,
however, in the amount of tension they impose on the
instrument and the “color” of the sounds they naturally
produce. The maker must be aware of and account for the

The string's signal

      When we stretch a string we charge it up with energy,
like a battery. The stretched string then exerts a
constant, static tension force on the instrument while at
rest. When we pluck that string, we disturb its static
state and release the stored-up energy in the form of a
complex, periodic vibration. The pulsating string create
tiny changes in the tension that it exerts on the
instrument’s neck and soundboard. These evanescent tension-
changes are the string's signal. Encoded within this signal
is the product of all the components of the Harmonic Series
the string is producing. The string-pulses set all the
instruments' surfaces--and the air inside of the soundbox--
into corresponding motion.
      Those distinct regions of the instrument that are able
comply with specific frequency components in the string
signal begin to vibrate in response. This is the phenomenon
called resonance. But there are many components of the
string signal that the instrument simply cannot comply with
and resonate. Those wave components stay bound up in the
string. Those that are matched are “sucked” out of the
string and their energy is what drives the resonances in
the instrument. So we can say that each instrument
“chooses” it’s own distinctive portion of the signals that
the string is feeding it. This is why a guitar sounds
different from a cuatro, or a violin, or a mandolin, even
though they all have similar vibrating strings. This also
explains the differences in sound between one cuatro and
another. Each instrument chooses which particular string
components to respond to and which to ignore.
      The difference in the sounds of two similar
instruments, or two completely different instruments, is due
to differences in their individual physical form and
structure. If one instrument has slightly thicker walls, or
if the soundbox is deeper or wider in size, or if its wood
is softer or harder, it will draw out of its moving strings
a slightly different combination of distinct frequency
components than the other can.
      So the sound of the instrument comes from its strings,
but what determines the portion of the string’s sound we
actually get to hear is the result of how it’s made, what
it’s made of and its physical shape and size.
      We must keep in mind that most instrument makers are
or were usually not engineers or acousticians, but instead
specialized craftsmen more familiar with wood than with
acoustics. Their stock in trade is not wave motion but the
capacity to recreate acoustic devices whose form was
derived from a specific historical, cultural and aesthetic
tradition. Instrument makers lack the ability to actually
see acoustic waves or perceive the wood surfaces vibrating
in all their daunting complexity. Their skill is solely
that of recreating cultural artifacts and transforming them
into tools that a musician can use to create art.
      Their sound and form is thus predominantly dictated by
history and tradition, rather than acoustical knowledge. As
Luciano Berio explained,

"They are concrete depositories of historical continuity. And
like working tools and buildings, they have a memory: 
they carry with them traces of the conceptual and social 
changes through which they were developed and transformed."
The first stringed instruments

      Evidence of how deep, primitive and compelling the
power of musical sounds is, is how early it was when
musical instruments arrived in the course of human
evolution. Evidence exists that musical instruments go back
as far as when the first humans hunted with bows and
arrows. Indeed, the first stringed instrument is thought to
be the actual hunter's bow.
      Undoubtedly, a hunter was once distracted by
rhythmically plucking the string of his bow, eliciting its
soothing sound. Soon he found that he could vary the sound
by flexing the bow, changing the strings tension and thus
the perceived pitch of its sound.
      The basic components of the hunter's bow are: the string--
elastic strips of rawhide, usually twisted to enhance its
uniformity-and a curved, elastic wooden rod. By virtue of
its elasticity, its tensile strength, and particularly by
its uniformity, the stretched string, once set into motion
by plucking, creates an ordered chorus of sounds. The bow
keeps the string in tension, and vibrates in response to
the dancing string--allowing the hunter to hear it. But not
very efficiently: the thin bow, while enabled by its form
to propel an arrow over a great distance is not very good
at converting the kinetic energy of the stretched string
into acoustic energy. But improvements followed.
      As time went by, the bow--originally a purely
utilitarian implement--became transformed by culture into a
specialized artifact of musical craft. This must likely
occurred after these early hunters placed the bow against
the cheek and discovered that the twanging sound could be
modulated, or changed in its harmonic content, by changing
the shape of the mouth. This is what the North American
Plains Indians did when they created their Mouth Bow. The
hollow cavity of the mouth became the first musical
resonator or soundbox.
      Later, certain indigenous tribes coupled the bow to
hollow gourds, further increasing the instrument's musical
efficiency. Examples of these are still found in Brazil and
Paraguay, with the Berimbau and Gualambao. These can even
be heard in Brazilian pop music today.
      Over the millennia those extraordinary objects,
capable of creating ordered and compelling sounds, evolved
from Africa and traveled to the Mideast. There they became
the earliest members of what became known as the lute
family. The musical bow’s rawhide strips became twisted
animal gut; the bow itself was transformed into the neck,
and the cheek or gourd became the resonant sound box.
Formally speaking, string instruments composed of a
soundbox with a neck attached at one end, over which
strings are stretched are members of what organologists
call the Lute Family.
      That family includes the Puerto Rican cuatro, as well
as its other native stringed instruments. But that is not
to say that the cuatro was derived from the lute. The word
"lute" has over the centuries been used to loosely describe
a myriad instruments from many different countries and
different cultures, each with distinctive shape and
stringing. So while our modern cuatro derives some of its
characteristics from the New Spanish Lute (Nuevo Laúd) of
the 19th century, it is in fact significantly different in
history, culture, form, size and stringing from the French
lute or the German or English lute. The only thing we can
say is that the cuatro is a member of the lute family
because it shares with the Spanish, English, German and
French lutes its neck and soundbox configuration. In turn
this form links them all back to the the Arab/Persian lutes
of great antiquity.
      The earliest examples of instruments from the lute
family were most likely crafted by early agrarian societies
with the same simple tools, available materials and
rudimentary techniques they used to make other implements
of their daily lives: the spoons, bowls, furniture, kitchen
tools, and farming implements.

Guild techniques
      The craft aspects of Latin American stringed
instruments point to an interesting social phenomenon. For
centuries, the manufacture of instruments made for the
elites and the bourgeoisie was overseen by ancient craft
societies known as the Guilds. The Guild system propelled
the refinement of the musical crafts to the greatest
heights ever known. They embodied an ancient tradition of
rigorous training and of strict standard-setting that
precipitated a flowering of the decorative arts over
hundreds of years, up until the system faded in the 19th
century with the advent of the Industrial Revolution.
      The highest technological advancements of their times
were utilized: treadle-powered machinery like bandsaws and
drills were introduced and edge tools and handsaws of the
best steel available were utilized. The finest exotic
hardwoods were imported from around the world.
      The strings themselves were the product of highly
specialized guilds, originally an offshoot of the nautical
cordiers or rope-makers. The ability to create strings of
unsurpassed uniformity--the principle requirement for the
most musical-sounding strings--was their stock in trade,
and a set of strings alone could cost more than several
      The Guilds were closed shops, that is, you could only
be born into them or at best, be invited in by existing
members. If your standards flagged or your work turned too
far afield you could be punished. Penalties for displeasing
the Guild masters included banishment from the profession,
banishment from the region, and even incarceration.
      Guild craftsmen developed the technique of sawing
plates thinly and planning them accurately so that they
could be curved with judiciously applied heat and moisture
into light, resonant, fancifully-shaped soundboxes.
Instruments made this way produced velvety-smooth,
sustaining notes that were appropriate for the refined
parlors and drawing rooms of the day. Often laden with
semi-precious stones and other rare inlay materials, they
served as presents to state officials from status-climbers,
or gifts of state between noblemen and kings.

The enterizo technique
      Because of their cost, instruments produced by the
Guilds were largely unavailable to the common folk.
      Folk musicians could only turn to local woodworkers,
rustic but resourceful craftsmen who brought to their task
slabs of local lumber and a sparse kit of tools that
included little more than knives and hatchets, scrapers,
hammers and awls. They lacked the technology and resources
for making saws that are required to slice wood into
bendable, thin sheets. Thus country folk in the Spanish
colonies, as their counterparts all over Europe, had to
make instruments in what they called enterizo or "whole"
way. The enterizo technique consisted of hewing the entire
body of the instrument: headstock, neck shaft, heel, sides
and back to shape from a single, continuous slab of solid
wood. A soundboard was then fashioned by chopping and
scraping a flat plate of softer wood, often with the bridge
carved out integrally as an rectangular lump on its
surface. The enterizo or unitary construction was an
ancient way of making instruments, dramatically different
from the way the Guilds did, building instrumentos de
piezas, that is, sawing thin sheets of wood into thin
plates, bending the sides and curving the plates,
assembling them into a complex soundbox by glueing them
together with small individual blocks, braces and grafts.
      Pablo Nassarre, theorist and organist of the Royal
Convent of San Francisco of Zaragoza, (1664-1730) described
the enterizo instruments of his day in his book, "Escuela
de Musica, segun la practica moderna" [Musical Method,
following the modern practice], Zaragoza, 1724, Book IV,
Chapter XVI in the section titled "de las proporciones" [on
the proportions].

"The form of this instrument is pyramidal, its lower extreme 
having a semicircular form. It was ordinarily made entirely 
of one piece (except the top) hollowed away in concave 

      To this very day, the enterizo method of making
musical instruments is common among many of the members of
the plucked-instrument family that evolved in Latin
America, notably the folk instruments families of Mexico,
Panama and Puerto Rico. The consequences of utilizing this
unique acoustical architecture with metal strings is a
loud, piercing tone--ideal for outdoor festivities and
community gatherings, be they secular or religious.
The enterizo technique in Puerto Rico
      Puerto Rico was a nation of carvers. As the prominent
Puerto Rican instrument maker Luis Acevedo Flores put it:

“ because the Puerto Rican artisan was eminently a wood 
carver, naturally, it occurred to him to carve his 
instruments, because that is what he knew. He was a great 
carving artisan: he carved his farm implements, he carved 
his kitchen implements, he carved the yokes for his oxen, 
he carved his mortars and pestles, he carved the beaters to 
shell coffee beans, to shell rice. So it would not be odd 
for them to take a piece of wood, hollow it and make a 
concave shape. And all that was left was to put on a top 
and play. Well that is what they did with the cuatro.

“ When we studied the furniture that was made in the past 
in Puerto Rico, we noted that they were generally carved 
furniture, where the finish work was always carved. And I 
can?t imagine, in any way, that in Puerto Rico the 
technique of wood bending was known. I don't think that 
wood bending techniques were known. I believe that 
craftsmen never used them because even pieces used in 
agriculture that appeared to be bent were actually cut from 
a solid piece of wood. They were never bent. And for me, it 
is difficult to imagine that if they knew bending 
techniques, they wouldn't use them when making instruments.
"When you observe someone who works in wood, you would 
definitively think it most logical to bend, from a 
structural point of view, because of the wood’s strength. 
Because that’s when the wood’s fibers are kept in their 
longest and most complete form. When we carve a curve we 
end up with “short grain” which is fragile and easy to 

“I honestly understand that perhaps it is conceivable that 
some people would know bending techniques, some coastal 
craftsmen who would work in shipbuilding, that had to bend 
the wood, and had to bend them cold, not with steam. By 
then in Spain, steam bending was known for a long time. But 
we don’t see that in Puerto Rico."

Friday, April 18, 2014

It's not easy being a luthier

I suspect that most instrument-making hand-builders have always been more than a bit jealous (and maybe even a bit resentful) at the way the large factory firms have always been able to command the lion’s share of the guitar-buying market. For years, many of us have had to struggle for the fickle attention of those few guitarists who remained unimpressed by the extraordinarily persuasive ballyhoo, shameless claims, image-manipulation and artist-endorsement ploys spread throughout the guitar media (and echoed compliantly inside music stores) by large guitar-making firms and their mass-produced instruments.

The irony is that many of us builder-technicians have had to correct, on a daily basis, the consequences of the bad judgment, failed design and shoddy workmanship of these same factory instruments. We are often dismayed at the customer’s passive resignation when told that they must now pay for the downside of mass production.

Indeed, what is most ironic is that such resignation is rare when customers of hand-made guitars spot a tiny rub-through or a little dot of glue squeeze-out, or other such oversight on their handmade instruments, and then proceed to nail luthiers to the wall for these sins.

That, perhaps, is as it should be. Yet, it all seems so colossally unfair when luthiers are nonetheless obliged to peg their prices to the price-ceiling of the factory lines, and not to the amount which the luthiers need to survive and prosper as they make these things at the slow, deliberate and careful pace that such strict standards require. It is interesting to note that professional violin-making luthiers, who largely don’t have to compete with a mass-produced product (and whose instruments are far smaller, less complex and require less expensive materials than guitars) commonly command over twice the fees that their equally-experienced guitar-making counterparts charge. If you want an excellent (new) hand made violin by a highly-regarded, expert maker, be prepared to pay $20,000 and up. If you want an excellent hand made guitar by a highly- regarded, expert maker, be prepared to pay between $5-10,000. Add to the asymmetry the fact that violins are made of maple, and fine guitars are expected to be made of distant, expensive exotics.

But I digress. Perhaps, once they’ve shelled out their hard-earned cash, customers find it far easier to hold the luthier's feet to the fire because there they are, the actual makers, in the flesh, standing right in front of them. On the other hand, large factory instrument-makers are more effectively shielded from their mistakes behind their sales staff, the store managers, the warranty restrictions, and a battery of lawyers on retainer. All these stand between the new-instrument buyer with the non-operative truss-rod, the elusive rattle, the misplaced bridge, or the new guitar in need of a neck reset—and the individuals whose mistakes, bad judgment, or expedience actually caused the problem.

Not for us, though. Rather than complain that we are a much abused, dying breed, we should take note of some heartening new developments in the market. A book published by a group of researchers at the Massachusetts Institute of Technology reveals how the market is increasingly turning to small production handcraft and losing its unquestioning loyalty to large factory mass-production.
The book, "Made in America: Regaining the Productive Edge," resulted from a study of American manufacturing trends. According to that study, the decline of American productivity and losses to foreign competitors is a reflection of "dinosaur strategies" such as the continued adoration of mass production."

Mass production has, until recently, insured the preeminence of American industry. Jobs became increasingly specialized and innovation in machinery was substituted for the skill of workers. A hierarchy was created, putting great distance between the person who designed the product and the person who assembled it, and both of them from the buyer.

As it did during the Industrial Revolution, mass production largely wiped out all other forms of production, such as craft-type manufacturing. At present, luthiers represent the few who remain, trying to recall, recreate and relive a bygone past.

True, mass production insured that things could be made cheaper by less-skilled workers, but it resulted in a reduction of the quality and variety of products available in the marketplace. This systems has worked fine, as long as store-bought meant status and people wanted precisely what their neighbors had. But things have apparently begun to change, and in a big way.

People now want products that suit their individual taste, needs, and self-image. Luthiers are poised, as a group, to best supply this need for personalized instruments, and although the large firms are taking note and are beginning to diversify their lines (witness Martin’s recent "new-guitar-model-of the-month" policy and factory "custom shops"), individual guitar-making artesans are best equipped to offer the unique and the one-of-a-kind better than they.

According to the same study, the world is coming around to what we always  figured: if you put your heart into your work; put excellence foremost among your intentions; keep a close watch on your checkbook balance; and hang in there, the world will beat a path to your door.

Friday, March 28, 2014

How Good is This Guitar?

I'm including an old article written under commission for Acoustic Guitar Magazine. Just some basic practical advice presented in a breezy, gee-whiz style. That's what they want.

How Good is This Guitar?
by William R. Cumpiano
© 1995 All Rights Reserved

You're buying a guitar, and it's time to make a decision. You've tried out a dozen different instruments: several brand-new ones and some used ones on consignment at the music store; an older guitar you liked that a friend is willing to part with; and some you found in your local paper's classified section. Finally, you've narrowed it down to just three or four that seem to fit your ear, your hand, your style, your wallet.

But wait! Have you asked all the RIGHT questions of each instrument? Can you tell which factors point to quality construction? Can you tell which factors point to a manufacturer trying to cut costs? Were you able to spot potentially expensive problems in the making?

A wry remark I've heard inside the luthier's trade goes, "if a guitar is easy to play and it stays in tune, you'll find someone who'll love it." This implies that people aren't usually willing to go beyond first impressions when evaluating a guitar for purchase. This may be true, but it needn't be thus. After you decide you "like" a guitar, it's far better to evaluate it the way a professional technician would: dispassionately.

An evaluation of this sort begins with a once-over. First, examine the guitar's stressed seams--those between the neck and the body, between the neck and the headstock, and between the bridge and the soundboard. Are they closed and tight? Next, scan the entire guitar, looking for ripples or bulges that really shouldn't be there. With a knuckle, rap all over the front and back and listen for rattles.

Now check the height of strings. The critical questions to ask are,

* "If the action is high, is there sufficient saddle protruding above the bridge to adjust it downward?"

* "if the action is low, is the saddle too high already to adjust it further upwards?"

Clearly, a excessively low (barely protruding) saddle or an excessively high (tottering or tipping-over) saddle can signal serious problems. They may reveal that the neck angle, and thus, the action, has changed--and someone has tried to make do rather than fix it.

The reason these all are crucial as primary observations is that they betray the instrument's general integrity, the precision of its construction, and its success in bearing up to string tension--matters of basic importance for the future prospects of the instrument. Make mental note of any marginal or suspicious observations for closer scrutiny later.

Now play the guitar. I usually like play a series of difficult or challenging rapid passages, and then perhaps several slow, singing musical fragments. This way, the guitar as a tool for making music is quickly revealed: its tactile responsiveness, its playability, its musicality. Often, these qualities are thought of as elusive, mysterious gifts that only a few rare instruments possess. Instead, they are rather straightforwardly the result of thoughtful design and accurate execution by the builder.

While determining a guitar's playability and responsiveness, note how much effort, how much concerted intent is required to achieve clear, well-formed individual notes, particularly rapid arpeggios. I pay attention to how well the guitar "forgives" my less-than-perfect articulation. This quality of "forgiveness" is a crucial quality which exists to varying degrees on different instruments. I wish I had a nickel for each time I've heard the remark, "I've never been able to play THAT passage quite as easily before." Some instruments let you play your best, others slow you down.

Evaluating the guitar's musicality is best done in the upper positions, while playing slow, singing passages. That satisfying sensation when the instrument wants to make music (rather than just a sequence of notes) is the result of its ability to produce accurate pitch, volume and sustain, evenly, in all positions. These qualities are most sorely tested in the upper positions, where pitch distortion is most noticeable and where short vibrating string lengths (with a corresponding reduction of the string's output) demand the most from the whole system. These qualities--playability, tactile responsiveness and musicality--exist in direct proportion to the fretboard accuracy, scale accuracy, and fretwork quality on the guitar. Fretboard accuracy demands not only that the fret intervals be cut true to formula, but that the fretboard's inclination (the "neck angle") be precisely correct. Scale accuracy requires that the bridge's placement be exactly correct. The quality of the fretwork depends on the firm, level seating, and the accurate milling of each and every fret. The ravages of time and tension, however, can take their toll, bringing on an inevitable, gradual degradation of all those qualities.

Such precision requires concerted attention and care on a new instrument when it's made, so you're most likely to find it on guitars made in the smallest batches, from shops with the most motivated and experienced builders. Or, you could have a reputable technician improve the instrument's fretwork and action, where it falls short--but later, and at a price. So if it has it now, you're ahead of the game.

Now let's check the stuff this guitar is made of. Your first interest should be the soundbox's materials: its "plates". First question: Are they laminated or "solid"? What's the difference? Does it matter? It certainly matters a great deal, to both the tone and cost of the instrument. Of all the timber which is commercially available, only 1% is suitable for instrument-making. This is partly due to the fact that many species that are prized for acoustic responsiveness are scarce and come from distant lands. When those species CAN be obtained in commercial quantities, they must then be accurately sawn in a way that, unfortunately, yields a lot of waste. Quarter-sawing, which results in a lot of wood in the sawmill dumpster, insures that thin wooden slices can retain maximum strength, resilience, and stability.

Laminating several paper-thin sheets of less valuable woods into plate thicknesses is the expedient, cost-cutting alternative. Now, as long as the outside surfaces are covered with the more valuable, prized material (cut in the more economical way), you can hardly tell it apart from the real thing. Laminated plates, however, have significantly greater sound-absorbing properties than solid plates, due to cross-plying and all the glue in between the sheets. Thus, a guitar with all its plates laminated--top, back and sides--comes to sound, typically, rather thin and sweet: pretty, but not much there.

The major cost in tone quality is paid when the SOUNDBOARD is laminated. The laminating of the back and sides has considerably less adverse impact. Thus, solid top, laminated back-and-side guitars usually result in the best sound-to-price value.

Can anything positive be said about laminated plates, other than their reduced cost? Yes, laminated plates will not crack due to dryness and will absorb greater abuse before breaking, making laminated instruments ideal knock-about guitars. Also, laminated instruments are easier to amplify: the reduced sensitivity of the plates reduces feedback problems to virtually nil. The venerable Ramirez builds many guitars with laminated SIDES. Classical-guitar sides are especially thin and thus, particularly fragile. The slight acoustical cost for using laminating sides is borne on these expensive Classics.

"So, how can I tell for sure?" Scrutinize the edge of the soundhole. A layered, sandwich effect betrays a laminated top. If, however, the grain lines on the top drop down across the entire thickness of the soundhole, the soundboard is solid. If the soundhole-edge is painted or otherwise covered, don't be fooled; it's laminated.

Making out the back and sides is tricky. Closely examine the interior back and side surfaces through the soundhole. Look for color variations or distinctive grain features on the surfaces. If these features do not have corresponding matches on the outside, assume the plates are laminated.

Guitars that are made up entirely of laminated plates are student-grade, entry-level instruments. You shouldn't be asked to spend over $250 for any of them, least of all if used. The addition of a solid spruce soundboard, however, initiates the instrument into the next quality category. Modest specimens of solid-soundboard guitars sell in stores for as little as $250, with the fancier (the ones with finer-quality tops and better hardware) going for around seven to eight hundred dollars. The finest guitars, however, are made entirely of solid-wood plates and start at around $1000 and go up from there.

All of these price-categories have been ratcheting steadily upwards over the years. During the fifties and sixties most tropical timbers, including those ideally suited for guitar construction, were cheap and plentiful. Even low-priced instruments of that period were made of solid woods. So, it's quite possible to find high-value used american-made guitars in that category which are superior in sound and construction but cheaper than newer, laminated ones. You've got to find them, though. If you have a new or used solid-wood guitar, what are the quality "signposts" to look for? Let's look closely at the soundboard. Take note of the fine comb of grain lines ("reeds") that travel lengthwise over the top. The tightness, or density of this grain pattern, contrary to popular misconception, is NOT the definitive sign of superior-quality tonewood. Acoustic quality derives from superior stiffness coupled with light weight. This occurs without regard to the number of reeds per inch. Far better evidence of a superior, well-selected soundboard is the UNIFORMITY in the grain pattern and the presence of medullary rays. Medullary rays (also called "silk") are cross-linking fibers that run perpendicularly across the grain lines. They impart not only a beautiful luminescence to the top, but superior strength and resilience as well. They are found in their richest profusion on the very best quarter-sawn soundboards.

On newer guitars, a pale-orange color denotes Alaskan ("Sitka") spruce, the most commonly-used soundboard wood by far. A paper-white color and a finer texture denotes either European "Silver" spruce (also known as Bavarian or German spruce) or Englemann spruce. These are rarer, more expensive species found only the more expensive factory and handmade models. Characteristically, the white spruces impart to the guitar a smoother, silkier tone than Sitka, which lends the tone more of a "bite".

Other coniferous softwoods such as cedar and redwood are slowly gaining acceptance as alternatives to the spruces on classic and steel-string guitars. You may note them on some guitars because they appear decidedly darker than spruce tops. Their growing popularity is due to their remarkable loudness. But spruce-top guitars invariably "mature", becoming fuller and richer in sound due the cumulative effects of many hours of playing. Cedar and redwood are reputed not to mature, however, and to be more fragile and fracture-prone, besides. Their characteristic loudness is certainly a plus, however, and you'd be surprised how well a factory-made, laminated-back-and-side, solid cedar top classical guitar can hold its own when compared to an expensive hand-made solid-wood instrument.

The specie of wood chosen for solid back and sides--usually maple, mahogany, East Indian rosewood or Brazilian rosewood-- dramatically affects a guitar's cost and perceived value. Maple is known as a "blond" wood, while mahogany is reddish-brown in hue. Both East Indian and Brazilian rosewood are chocolate brown, but you can tell them apart by their darker-pigment figure: Indian is streaked with dark brown, soft-edged flecks and lines, while Brazilian displays spidery-sharp blue-black lines meandering along its surface. The difference between the rosewoods, in terms of their acoustic quality, is in fact rather insignificant. Nevertheless, a mystique has grown around Brazilian rosewood which clouds objective assessments of its value. Whereas mahogany and maple can be had for a few dollars a pound and East Indian rosewood (albeit costly) is still relatively plentiful, Brazilian rosewood has become one of the rarest and most expensive exotic hardwoods on the planet! Needless to say, many "connoisseurs" are unduly swayed by this fact. Yet truly, a well-made mahogany or maple guitar can be every bit as "good" as one made from Brazilian rosewood. The difference is the subtle tone coloration imparted by the different species: all other things being equal, maple and mahogany are associated with a warm, blended tone, while the rosewoods lend a glassy clarity to it. In this instance, the right question should be, "which do I prefer?" not, "which is the best?"

Now let's look at the guitar's neck. Here, straight and homogeneous grain is crucial. If you can spot any dramatic sworls or striking changes in the grain texture, put the instrument back on the rack--it's likely to be a "reactive" neck. Sharp, protruding fret ends can be a danger sign, too. They may betray a ill-seasoned fingerboard, so suspect other poorly-selected materials on the guitar. Alternatively, they may give evidence that the guitar has been exposed to a chronically dry, overheated environment. In either case, you should suspect drying out (i.e., cracks, shrinking) on other parts of the instrument. Examine the frets and the fretboard surface, especially under the strings. A guitar that has been played a great deal will develop characteristic wear patterns on its frets, such as dents, valleys and "flat-tops". A sharp detective can reveal a lot about the previous owner's playing style and musical preferences from these patterns. What's more important to you, however, is that fret wear significantly degrades an instrument's tone, playability and pitch accuracy. Resurfacing the existing frets, (or replacing old with new) is a fairly expensive proposition. On a new instrument, a good benchmark for workmanship is how uniformly shaped the fret-ends appear. On an older instrument, uneven fret-ends can show a long history of fretwork, and the likelihood that some frets may have come loose.

"Sighting" the neck is an exercise that can reveal several important faults. You can sight the neck (like a carpenter sights a board) by bringing one eye close to the edge of the fingerboard, and view it down its length towards the bridge or conversely, towards the nut. Thus, it is possible to see the fingerboard in a foreshortened way, making some special relationships easier to evaluate. You can, for example, determine if the neck is twisted by comparing the level of the upper frets, seen in foreground, relative to the level of the nut, seen in the background. If they do not seem parallel the neck is twisted, meaning that optimum action and playability is not possible until it is remedied. Also, any "kinks" along the length of the fingerboard, which would otherwise be unnoticeable while looking straight on, can become obvious while sighting. A popular misconception is that the ideal sighting is a fingerboard edge which is dead-straight along its entire length. Instead, a better sighting would be a very slight, evenly-swept upward curve--barely noticeable on a Classic, but more evident on a Steel string--and about equal on both sides. A dramatic upwards- crook right where the neck meets the body can signal that an expensive neck-reset is in the cards for that instrument.

As far as neck comfort, it's surprising how slight variations in neck-shaft contour can affect playing comfort. An inappropriately-contoured neck will rapidly tire the hand muscles at the base of the thumb. The neck should feel unobtrusive and graceful in the hand. Don't hesitate to play a guitar at length to fully evaluate its comfort over long playing periods, but keep in mind that, if you like all else about an instrument, you can have the neck recontoured later by a skilled technician.

A major quality-benchmark on an instrument is its finish. Cheap finishes are thick finishes. Like the drooping film covering a candy apple, a cheap finish is thick and wavy, with bright but indistinct highlights. All protruding corners are rounded over, and interior corners are rounded, too. On older guitars, thick finishes have a propensity to check, displaying a pattern of spider-web fracture-lines. The worst finishes (and, alas, the most ubiquitous) are thick, catalyzed-epoxy finishes that can shrink and crack over time, forcing the wood below to crack also and to pucker, like baked mud. High-quality finishes are usually clear and untinted, crystalline in texture, uniform in gloss like a fine mirror, and with sharply-focused highlights. All the guitars edges and features remain sharp and well-defined. Ideally, the function of the finish is simply to keep the wood surfaces from accumulating dirt from handling. Unfortunately, the finish (especially on new guitars) also acts like a damp blanket, muffling the sound: so it is a necessary evil, and so less is truly more. The reason you'll find thin finishes on more expensive guitars is because it takes great skill to apply a thin finish evenly and then polish it without rubbing through. The large-factory solution is to apply dozens of coats and then to press the whole instrument up against a large polishing machine: the likelihood of rubbing through is thus reduced.

Talking about cracks, some are trivial and some are not. Cracks in the finish can travel with and across the grain. Cracks in the wood (excepting impact damage) travel strictly along the grain. Cracks can point to the guitar's being subjected to an adverse environment for extended periods. While finish cracks are indeed trivial for the most part, cracks in the wood may or may not be. One test to ascertain the seriousness of a wood crack is to alternatively press on the plate on either side of the crack. If the plate behaves as if it were still joined across the crack, it is often just a thin, hairline split that can be quickly repaired by working a little white or yellow glue into it and applying light pressure over it to close it while the glue sets. If the two sides of the crack move independently from each other, the crack must be knitted together by a skilled person. If left untended, the crack may just remain stable indefinitely, or (if in a region of stress) will grow in size, and eventually pucker. Then, a difficult, expensive repair job is in the works. Regardless, two or three soundbox cracks on a good guitar (if tended to) should in no way affect the future prospects of an otherwise good instrument. Neck cracks are a different matter altogether. While splits in the fingerboard are usually inconsequential, cracks in the shaft, heel or headstock region are extremely serious. Have a skilled technician evaluate them before buying the guitar.

Tension stress eventually takes a toll on every guitar, and it is the natural result of how guitars are made. The effect of string tension, normally, is to bow the neck upwards slightly and to cause the bridge to twist downward towards the soundhole. The presence of tension distortion of the neck to a greater or lesser degree is not unusual, even on the very best instruments. Soundbox distortion is, however, and should cause great concern. Whereas tension on the neck slowly causes the string action to rise, tension on the soundboard is trying to cause the soundboard to collapse. That it doesn't on a lightly-built fine instrument over the span of a lifetime is a tribute to the skill of the builder. Indeed, well-made guitars do react to tension, but they usually stabilize into a more or less permanent configuration. Other guitars, nevertheless, are time-bombs which are actively collapsing, in slow motion. Evidence of slow (and slowly accelerating) collapse is a marked tipping-over of the bridge, strings laying exceedingly low on the fretboard (notwithstanding a tall saddle) and an ugly bulging of the soundboard behind the bridge. Ripples, lumps, or hollows on any of the plates should be cause for alarm also, being evidence of collapsing interior structure.

Now that you've had a chance to take a closer look at the guitar you were about to buy, doesn't it feel better to know that you've brought a little bit of sensible skepticism into the process? Now you know why the man was trying to sell that guitar with high string action and a low,low saddle. You've also been given a little more ammunition in case you have to bargain with the owner over the price of an instrument which passed the examination but nonetheless needs an expensive fret job. Now, pay the man, take it to a good technician to adjust the action to your particular taste, and enjoy your new guitar!

Sunday, January 26, 2014

Wedge issues

Mr. Cumpiano, thanks so much for your book. I have been building electric guitars for about 7 years, and did not know where to begin with acoustics until I found your book. I plan to build my first acoustic this year following your methods, but was wanting to incorporate a wedge, since I have shoulder issues.  How do I sand the long radius (heel to headblock) in the back rims when both sides are not identical? If you can provide any advice or help I would greatly appreciate it.


I attempted the wedge only after I was well into my guitarmaking career. I had made over a hundred guitars before attempting it. And I still found it so challenging that I’m not looking forward to doing it again soon. So I would say that it is probably a very bad first guitar-making project. The geometry is so weird, I wouldn’t even know how to clearly explain how I trimmed the sides, tailblock and headblock to the precise contour, let alone apply back kerfing strips to the meandering perimeter of the back.

Instead, consider a “thinline” acoustic: they actually sound very good: Not a wedge, they are built in the ordinary way, just that the side height is 3 3/4-inches at the tailblock, tapering to 3 1/4 at the heel. You make up for the lack of air volume (e.g. bass response) by making the bout width a jumbo 16-inches. It adds up to a Jumbo with an OM-guitar air volume. It’s the next best thing to a wedge.

William Cumpiano