Steel String Guitar Basics

Almost everybody knows that a steel string guitar has metal strings, as opposed to classical guitars, which are strung with nylon. But many people don’t know anything else about the steel string guitar’s construction, its parts, its materials, or its origins — other than that they know and associate the name Martin with such guitars. This is intended to be a beginner’s level introduction to this versatile and interesting stringed instrument.


Classical Guitar

Steel String Guitar

Why are there six strings? 

Seventeenth and eighteenth century guitars had five strings, or sometimes five pairs of strings. These were used to play music which was fairly simple in structure in that much of it comprised of single note melody runs and chords made up of only a few notes. These instruments all replaced earlier, four-string ones which played even simpler monophonic music.

In due time it was found that the addition of a sixth, lower, string made the guitar a much more satisfyingly expressive instrument. It could then play a wider and more complex range of music, and also, by virtue of the addition to the bass register, the music sounded richer. Today, with the exception of a few guitars which have eight or ten strings and are used to play extended-range music, all guitars have six (or six pairs of) strings. It is, in fact, the arrangement that works best to express almost all music, as humans like it, today: if the guitar had fewer or more strings it would be limited in that it would not express some music very well, or it would become a specialist toward expressing some other kinds of music very well indeed. Six is, in effect, the most workable compromise yet found for guitars.

Lutes, interestingly, had a very similar history. The first lutes had six courses (five doubles and a single high string), or eleven strings. As lute music and technique changed, and as audiences grew larger and created a need for louder and louder lutes, luthiers kept on enlarging the beast until in the Baroque era — in which both music and decorative art were over the top in lushness and complexity — the lute had twenty-eight strings. No single one of these models of the lute ever dominated, by the way; they just kept on growing until they couldn’t grow any more. Today, lovers of early music have generally preferred the eight-course lute (seven doubles and one single) . . . as the best compromise instrument that allows them to play both the simpler early music and also the more lush Baroque repertoire. In exactly the same way — except for the fact that it is dominant — the six string guitar is a compromise that has defined what the guitar ought to be.

Were there always metal string guitars?

No. The technology for making metal strings developed late. The first guitars were strung with gut, as had been violins and early bowed and plucked instruments. The early gut was problematic: it was usually uneven, and it didn’t last very long. The ability to produce thin, strong and evenly thicknessed gut strings was made possible by adapting rope-making technology — the twisting together of a few thin strands of material into something even and strong — which had been used ever since there were sailing ships for which to make ropes.

This technology itself got a mighty boost when European nations from the fifteenth century onwards found themselves competing in the building of navies and oceangoing vessels of commerce, conquest and exploration. There was a rather sudden demand for large quantities of strong, reliable, and durable rope; and so braided rope came into being. This technology was adapted, in due time, to the smaller-scale ‘ropes’ of musical instrument string making. The first instruments that we would recognize as the modern guitar had six strings that were made of gut that was twisted and braided together just as rope was. This early (gut-strung) Spanish guitar eventually led to the birth of the steel string guitar.

Parenthetically, the ropes and rigging on large ships allowed the sailors to climb high up and do the balancing acts and high-wire maneuvering necessary to work the sails. This was delicate work, and one needed the agility of a cat up there. These ropes came to be called ‘catlines’ (pronounced ‘catlins’) — the root of which later gave us catwalk, a maneuverable path high up off the ground in theatres and other large buildings). Later, as musical instrument’s strings were produced in the same way as ‘catlines’ were — although on a smaller scale — these came to be called ‘catgut’ in spite of the fact that they were in reality made from strips of sheep’s intestines instead of fiber, cotton, or hemp.

How did the steel string guitar originate?

The steel string guitar, as we know it, developed within a few decades of the Spanish guitar. It did not come out of any of the European guitarmaking centers of Spain, Germany, France or Italy, but rather developed in the United States. It did so in response to the growing musical needs of a rapidly expanding and mobile population, and a steadily increasing popular culture. This growth was key, because it created a huge demand. And it coincided with the time when technology made possible, for the fist time, the availability of plentiful and cheap wire strings instead of the tempermental and expensive gut ones.

Wiremaking technology was itself a late development of the industrial revolution. It occurred hand in hand with the astonishingly fast conquest and subdivision of the American landmass by hordes of settlers who needed wire fencing to mark the boundaries of their land and keep their cattle from wandering off into their neighbors’. Thus, wire was produced in huge quantities. And as wire for fences was produced, so could wire strings be made cheaply for guitars. Wire strings had been made previously, but before the industrial revolution these were laborious to produce. But now, as I said, there was an exponentially growing market for musical instruments within a migrating and expanding population.

Those early metal-string guitars were made quickly, cheaply and in large quantities in the factories and production shops of the day. It was an advantage that one could learn to strum on a guitar more easily than learning to play a violin or a piano; it made chord harmonies that were pleasant to listen to; and it could accompany singing, which made it a social instrument. Moreover, metal strings would last a long time — whether you stayed put or moved around, and in all weathers. Gut strings, which had been the only choice until then, were expensive (a single string could cost a week’s disposable income for the average workingman!), were affected by weather so as to change their tuning, and frayed and wore out easily. With the advent of metal strings, the guitar became an accessible, affordable, and popular folk instrument that didn’t need to be re-tuned every time you picked it up. I should add that guitars had all been made exactly the same way up until then, and were geared to the (lesser) pull of nylon strings; the first of these guitars to have metal strings put on them didn’t last. But that problem was quickly overcome by making guitars meant for steel strings sturdier.

Nylon guitar strings were developed in the 1940s as an outgrowth of the search for uses for a new kind of stretchy fluorocarbon polymer substance that had been discovered by accident in the DuPont laboratories in 1930. Some practical uses turned out to be in nylon stockings (silk ran too easily) and nylon monofilament for fishing lines. In fact, the first musicians to put nylon monofilament on their guitars — in lieu of gut strings — were the fishermen-musicians of the Spanish Mediterranean seaports. Incidentally, as Southern Spain is the cradle of flamenco those fishermen would have been playing flamenco when they partied; thus we are all indebted to the flamenco community for helping to discover that nylon could do for the classical and flamenco guitars what metal strings did for the steel string folk guitar. Albert Augustine, in collaboration with Andres Segovia, manufactured the first successful nylon guitar strings in 1948 — thus allowing the classical guitar to be played and enjoyed by millions of people.

What is the importance of the Martin brand? 

One of the first of the steel string guitar makers to establish themselves in the United States was a transplanted German woodworker, C.F. Martin, whose great-grandson now presides over the Martin factories. While there have been many steel string guitarmakers and many steel string guitars, it has been the Martin brand more than any other — and especially the Martin dreadnought guitar — which really put steel strings on the map, just as as Henry Ford put the early automobile on the map. The Martin dreadnought is the most common, popular and familiar steel string guitar on the planet today. Everyone recognizes it. Everyone copies it. Historically, it has been the example and model for modern steel string guitars in general, and the Martin guitar in particular has been the standard against which other steel string guitars have been judged.

Besides the strings, what is the difference between a Martin and a Spanish guitar? 

The difference in stringing is obvious, but this is only a superficial difference. The most meaningful differences are internal and structural, and have to do with the fact that the steel string guitar must be built to withstand relatively great string tension, compared to the nylon or gut strung guitar. Being built differently, they produce tone differently. And being driven by metallic and polymer strings, respectively, they also will produce different tones and tonalities. From an engineering standpoint, these are different instruments that share the same name. The principal elements unique to the steel string guitar are its smaller neck size, shorter strings, the X-bracing under the face, and the design of the bridge.

How are steel string guitar necks different from Spanish guitar necks?

There are three main differences. First, given the constant pull from metal strings, a reinforcing element is needed to protect an otherwise relatively thin and flimsy neck from warping or bowing. Formerly, non-adjustable hardwood or metal rods were commonly used. Today, virtually all steel string guitars have adjustable tensioning rods with access ports either behind the nut or through the soundhole. Spanish guitar necks are under much less of a load and have not needed reinforcing rods.

The second difference is in the shape of the neck, which serves a particular playing style. Spanish guitars were developed primarily for that style of playing in which the thumb is anchored behind the neck, allowing the wrist to bend and extend the fingers of the left hand over the fretboard while the fingers of the right hand pluck the strings. Accordingly, this neck is wide and the back of it is a somewhat flattened, gentle curve. The steel string guitar was developed originally for a playing style in which the thumb of the left hand wraps itself around the neck and the right hand plays the strings with a plectrum. Therefore, the steel string guitar neck is narrow with closer string spacing. It also has a somewhat Vee-shaped cross-section with a softly rounded peak in the back. This feature optimizes the ability of the player to wrap his hand around the neck, and its “v” shape fits into the valley between the thumb and the other fingers. It’s quite an efficient design.

The third thing is that steel string guitar fingerboards are crowned or curved, whereas Spanish guitar fingerboards are usually flat. There are several reasons for this. First, it’s easier for a left hand to bar over the stiffer metal strings on a slightly curved surface. Second, a slightly arched plane of strings (as the violin’s strings are arched over the fingerboard) makes it slightly easier for a player to play the strings with a plectrum.

Why is the steel string guitar bridge different from the Spanish? 

Spanish guitar bridges are designed so the strings can tie onto them directly. This design works well within the holding power of the glue joint that attaches the bridge onto the guitar face. With the advent of metal strings, however, it was found that the forces acting on the bridge were so great that such bridges could, in time, become unglued. A better solution was to anchor the strings to the underside of the face itself, and bypassing the possibility of glue failure at the bridge. Thus, in steel string guitars, the strings pass through the bridge into the guitar’s body cavity.

There’s an equally important second difference in that the Spanish guitar saddle — the bone (or plastic) piece in the bridge on which the strings rest — is perpendicular to the strings, while the steel string saddle is at an angle. This is necessary because the mass and stiffness of metal strings affects their vibrational activity and creates out-of-tuneness. The rate of change in these factors increases with the diameter of the strings: with equal-length strings the out-of-tuneness would increase with the diameter of the string. Accordingly the heavier, stiffer strings are compensated for this function by being made longer, and the slanted saddle is called a compensated saddle.

How is bracing important? 

All guitars have internal bracing, whose acoustic functions far outweigh its structural ones in that the manner of bracing shapes the possibilities for sound. Spanish and steel string guitars have different, characteristic bracing because they need to accomplish different tonal tasks.

The Spanish guitar, being subject to the lesser pull of nylon strings, has been found to function very well with thin braces which run parallel or almost parallel to the grain of the top wood. Steel string guitars are under significantly more driving load and consequently need more substantial bracing bars to withstand the resultant pull and torque. It’s these deformational pressures which have brought about the use of the “X” brace, which is the standard internal support for steel string guitar faces. An important function of the “X” brace is to support the part of the guitar face in front of the bridge from sagging downwards, as it would otherwise do.

Why not use one kind of bracing on all guitars, but sized to the structural pull of the string tensions, and the music to be played? 

The fan-braced guitar is a European invention and the “X” braced guitar is an American one; they were invented virtually simultaneously and very likely independently on one another. The first “X” braced guitars were of course made with and for gut strings, as were the Spanish ones; but both of these were descended from earlier versions of guitars that had ladder (three or four parallel braces that went across the grain) bracing.

Consider the fact that the modern Spanish guitar was first made in Seville, and the first modern American guitars were made in New York.

The Spanish guitar makers made guitars within a climate that was reasonably consistent. The American guitar was born in the large Eastern population centers, and then traveled West into all climates, humidities, and altitudes. The seasons on the Eastern seabord are notoriously extreme . . . and guitars are made of wood, which reacts to weather. It was discovered that guitars could survive the seasonal expansion and shrinkage of their materials (in those environments) better if their braces went across the grain and locked its fibers into place against movement. The “X” brace accomplished exactly that; fan braces didn’t really need that kind of protection.

Why are there so many sizes and shapes of steel string guitars to choose from, while classic guitars are all very nearly the same size and shape?

The answer has to do with the culture of the guitar and its music. The classical guitar is considered almost perfect by its adherents, and significant innovations are not encouraged. Builders are largely of a mindset to refine the established design elements, but not to alter them. The steel string guitar world, however, is not bound by such thinking and is consequently free to invent new versions and features as long as someone will buy them. Much of this impetus comes from the commercial industry’s need to constantly develop new products — much as the automobile industry has the same need. In both, consequently, models are sometimes released which are actually worse than previous ones. If a famous classic guitar maker were to ever develop a new model of guitar which sounded worse but was instead marketed for some saleable and innovative feature of design, his professional reputation would take decades to recover. But in the world of the steel string guitar, especially on the factory level, no one thinks twice about such excursions into commercialism.

Another and more interesting reason is that steel string guitar music and its playing techniques are changing. Change creates new needs, and these call forth new design efforts. In the classical guitar world these factors are moving ahead comparatively slowly as technique, repertoire, and acceptability of design are comparatively frozen. Moreover, one of the principal changes affecting the steel string guitar is that whereas it has for most of its existence been principally an accompanying and backup instrument (for voice and/or other instruments), it has strongly grown into a new identity within the past forty years as a solo instrument. In 1950 there were no steel string guitar soloists, interpreters, arrangers or composers; today there are many, and some of them are astonishingly good. As musicians have begun to explore and discover new tonal, dynamic and compositional possibilities, the steel string guitar has for the first time experienced demands on it whereby it is expected to function at higher levels of responsiveness to technique, liveness, expressiveness in tonal coloration, texture and subtlety, dynamic range in volume as well as sound quality, evenness, projection, sustain, playability, fidelity of intonation all the way up and down the neck, and, finally, ease of amplification and recordability. And this instrument is expected to do these things on sound stages, in recording studios, concert halls, auditoriums and in small rooms, as well as outdoors. This is a very exciting time for the steel string guitar and no one is aware of any reason to think these factors will not continue to grow for decades to come.