Guitar Necks
Neck Shapes / Profiles
Historic perspective: The early necks of guitars had two primary design concerns — they had to fit the hand but they also had to be structurally capable of withstanding string tension without warping. The earliest necks were quite short and were required to withstand tension of gut strings – sometimes in multiple courses. Dense wood was the natural selection — rock maple, mahogany and similar woods worked well for short scales. This was OK considering the instruments were considered Parlor or small acoustic ensemble instruments. They simply weren’t required to produce too much sound. They were one of the few instruments deemed suitable for women to play in social settings and therefore were not considered too taxing to manipulation by delicate fingers.
The design problem arose with the need for more volume. Longer scales and bigger bodies required necks that could resist greater tension. To make matters worse, thicker, heavier strings at higher tension produce greater sound. Unreinforced necks began to warp and bend in the direction of tension. At first, the addition of denser heavier wood spines, like ebony, offered slightly greater resistance, but they too warped over time.
The Bessemer process of producing steel was patented in 1855 introducing a new set of problems. Shortly afterwards, steel strings were possible in very uniform gauges, and heavy ones at that. They were more like cables than the lighter gauge strings we use today. Oh but they sounded good and they were much louder.
The Martin Guitar Company attempted to solve the problem with “T” and square shaped steel inserts in the wooden necks. They also exaggerating the vertical section of the neck to help resist string tension. It worked, sort of. Then their bridges popped off the bodies leading to new bracing systems and bridge plate designs – but that’s another topic altogether.
The necks tended to be as large in cross section as the size of an average hand would allow. It wasn’t long before the playing public clamored for relief.
Half-round sections were shaved to a deep “V” section to reduce the amount of neck mass while leaving the maximum depth to resist warpage.
Orville Gibson solved part of the problem by the introduction of the archtop guitar. His new design solved one of the two design problems created by heavy steel strings — There was no glued-down bridge. The archtop guitar had a floating bridge like a violin, cello or bass. The structure of the instrument could now easily support the new steel strings (even of very heavy gauge and full tension) by attaching them to the heal of the body. These instruments were loud. Remember, there were no amplifiers at the time. They were acoustically loud enough to participate in brass bands. They competed with banjos. Not only that – they were sturdy and could be played hard for maximum projection. Now the problem was the necks.
The adjustable truss rod was developed by Thaddeus McHugh (an employee of the Gibson company) and patented by Gibson in 1921, appearing in banjos, guitars, mandolins and anything Gibson made with steel strings. Acoustical engineer and professional player Lloyd Loar joined Gibson in 1919 and brought numerous design improvements; laying the groundwork for one of the primary instruments of the late Jazz era and the beginning of the age of the Big Bands and Swing. The adjustable truss rod solved the structural problems of the neck and allowed neck shapes to begin to respond to the desires and comfort of the players.
The advent of amplification also played a role in neck development. Once guitars could be amplified they no longer needed the very heavy gauge steel strings to develop volume. The electronics could do that with ease. Steel string gauge could be much lighter and easier to play. Lighter strings means less tension on the neck. Less tension means the necks could get even thinner. Now, neck shape was entirely an issue of comfort and preference.
The deep “V” persisted for many years due to tradition and the fact that Gibson fiercely defended it’s patent rights on the adjustable truss rod for the full term of the patent. Martin Guitars didn’t start using an adjustable truss rod until 1985.
The hard “V” shape slowly gave way to a softer “V” and eventually an oval shape favoring the deeper structural section of the neck. Since the steel truss rod was actually doing all the work of resisting string tension, eventually the neck sections became half-round and then “C” shaped — thinner in the center. There are innumerable variations: rounded “U”, flat oval, flat oval “C”, slim taper, etc. The issue became comfort. Electric players seemed to want “Fast” necks of thin profile and the Jazz players seemed to prefer more rounded profiles for comfort.
The 1950’s proved pivotal; the Fender Broadcaster, no-caster, and then Telecaster and Stratocaster necks started slightly larger and thinned over the decade. The early years, 1950 to 1954 saw “V” and deep oval shapes. 1955 & ‘56 produced both “V” and rounded necks. The shape continued to be thinned out through 1959. Likewise the Gibson Les Paul started life with a chunky neck and evolved to a thin taper in 1959 along with the SG, 335 and other electric models.
Around 1959 all of the guitar companies seemed to catch on to the public preference for thinner necks. Some models went entirely overboard – too thin. The experimentation extended to the neck widths, which began to shrink as well. Some acoustic and electric models of the early 1960’s have not been preferred over time due to their narrow neck dimensions. Today, new and old neck shapes are readily available and if one can’t find a factory-made instrument that fits their particular needs; many Luthiers are available to custom build a neck to the precise dimensions and desires of any player.
Styles of music have always had an impact on the favored shape of necks. The demands of Jazz call for an entirely different neck shape than the rapid-fire shred leads of thrash (you need to have a thin neck if you’re wearing twelve heavy rings on your fret hand…)
Current Martin Neck Profiles:
- Low Profile: The standard Martin neck profile found on D sized and standard series guitars.
- Modified V-Shape: Still the same width and depth of the low profile but with shaved sides for a rounded “V” shape. This harkens back to the early Martin neck profiles and can be found on Vintage, Golden Era, Marquis, Limited Editions and the 1833 Custom Series guitars.
- Low Oval: A slimmer feel similar to electric guitars – found on the X-Series little Martins, the DX1 and the 15 series dreadnaughts.
- Modified Low Oval: The same thickness as the low profile but a bit more rounded. This shape can be found on some Martin Limited Editions and on the Martin 16 series and X series acoustic-electrics.
Neck Construction
The traditional neck is made from a stable wood of straight and uniform grain. If there is radial motion in the grain, there is a chance that the neck can acquire a torsional twist over time. Lesser instruments had necks carved of a single piece of wood – maple or mahogany. Classical instruments favored Spanish cedar, which was slightly lighter. Steel string tradition, unlike classicals, did not stack wood for the heal or headstock bend – they pulled them from single pieces of wood leaving quite a bit of wastage. It didn’t appear to matter at the time since the wood was inexpensive and plentiful.
More expensive instruments favored laminating three, five or more layers. This had a distinct advantage: the layers could allow selected pieces of wood for their grain orientation, grain appearance, color and structural integrity. The final product was not only stronger than a single piece of wood but more visually striking. On top of all that, it had less wastage in the manufacturing process. The only downside was the additional labor to create it.
The traditional neck joint is a tapered dovetail. This creates a strong bond to the body of the instrument – very well suited to the task of resisting the overturning moment: the desire of the neck to be pulled up by the string tension. This method had the additional advantage of been repairable (by well trained hands) in the event that it needed to be later removed and adjusted for refit.
In 1950 Leo Fender brought an entirely new concept to the industry: Mass production. All instrument making prior to this were in the tradition of Lutherie – the wood worker’s craft. Leo Fender reconceived guitars as musician’s tools. They were nothing more than the assembly of mass-produced parts. The guitar neck became a bolted-on component. The earliest designs were manufactured from a single piece of maple. It was from a relatively flat board that included the headstock and neck heel. To minimize wastage, the headstock angle was eliminated as was the neck heel. The top of the neck was radiused to accept the frets directly with no fingerboard (fewer manufacturing steps) and the back was routed to accept the truss rod. In an ironic artistic move: the truss rod rout was filled with a contrasting wood: Walnut. The nut was also routed into the maple along with simple dot markers. The final product was attached with 4 screws and a metal plate into the body. The process required cheap manufacturing labor, not skilled woodworkers. The guitar entered the manufacturing age.
Fret Boards
Tradition has it that guitar fret boards are made of rosewood or ebony. The rosewood used on more common models and the ebony used on more expensive models. Sometimes rosewood was used and died to appear black like ebony. The selection of either wood was weight and density. Both are very dense and can withstand the constant contact of strings, fingernails and flesh. More recently there has been a shift in tradition where the beauty of a natural grained rosewood may be preferred over ebony.
With the scarcity of ebony and certain rosewoods, there is finally experimentation with other dense woods that function very well as fret boards. Tradition is slowly giving way to new possibilities — more dramatic and exotic grain visible as fret boards.
Fret Materials and Profiles
Hardened steel and high carbon steel are the preferred fret material. Stainless steel and bronze are available but are generally viewed as too soft since they wear out quickly. Many foreign manufacturers use a softer steel for frets as it is cheaper, easier to dress and polish and therefore faster to set-up the instrument. Faster set-up means higher profit. It also means that they wear out faster.
Frets come in numerous profiles: low-wide, low-narrow, wide-tall, narrow-tall, etc. Each has a particular feel and tradition. The older Gibsons, for example, favor the wide fret profile. Many acoustic players favor narrow frets. Contrary to popular belief, there is no difference in intonation between wide or narrow frets provided they are properly dressed.
There are some distinct differences in “feel” between fret profiles. For example, tall frets can hinder a player that presses the frets hard creating intonation problems by stretching the strings down behind frets. The same phenomenon can be highly desirable to players with a light touch who can use the height to slightly bend the strings or use the depth for vibrato.
Nut Width and String Spacing
It is amazing to me how many players feel very strongly about the nut width. Remarkably, the string spacing may be a bigger factor in comfort than the nut width. That being said: the most popular American size appears to be 1 ¾”. Some fingerstyle players like it just a bit wider at 1 13/16″, and then there are the classical players who insist upon 2″. There are also those who like it narrower: 1 11/16″ – often as a crossover from playing electric. Our feeling is that there are too many factors in determining the comfort and playability of a neck to insist upon one width over another. The 1st position feels entirely differently on a slim-taper neck than a deep “C” even though the nut width may be exactly 1 3/4″ on both. The trick is: try everything and go with the combination that feels right to your hands and playing style.
A few words on string spacing: the two E strings must be properly set in from the edge of the fretboard. They cannot be too close or the action of the fingers will push them off the taper of the edge of the frets. If properly placed: the thumb rolled over the top of the fretboard can easily fret the low E string and the High E can be slightly pulled up or down without snapping off the frets. The dimension is not set because different Luthiers have different methods and practices for dressing the edges of the frets. Some have soft rounded shoulders and some sharper cut-offs. The placement of the nut slots for the two E strings needs to take all of that into consideration.
There is debate regarding the best string spacing between the two E’s. Most strings are evenly set on equal centerlines. Some, like Robert Benedetto, set the strings so there are equal spaces between them. The gauge of the low E, for example, is thicker than the B string – those thicknesses are taken into consideration and the strings spaced accordingly. The two methods yield results that truly can be felt, even though the differences are very small. It is all a matter of preference.
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