McLaughlin's Revolutionary Drone-String Guitar

By Tom Wheeler
(Reprinted From Guitar Player magazine: August 1978)

 

Abe Wechter (R) with John McLaughlin
and specially made Gibson 13-string guitar.

Photo: Mike Aldsworth/Gibson

JOHN MCLAUGHLIN'S Gibson acoustic guitar, like his music, is unique. The result of a whole series of experimental projects, its features immediately distinguish it from all other instruments. The most obvious departure from conventional guitar design is a set of seven drone strings - which can be retuned from song to song - positioned underneath and diagonal to the six standard strings; the extra set may be either strummed or simply allowed to vibrate in consonance with the regular strings. But there are other radical innovations as well, including a scalloped fingerboard - the area between the frets is scooped out in concave semicircles - and a particularly unusual internal bracing arrangement.
Abraham Wechter, a consulting luthier for Gibson, built the guitar. He recalls, "The drone strings are entirely John's idea. He knew that he wanted them and that they should be positioned obliquely across the soundhole, but otherwise his whole concept was pretty general at first. Initially he thought that he might want to accomplish this on an arch-top guitar, but we settled on a flat-top." In late 1974 or early 1975, John began to collaborate with Gibson's director of research and development, Bruce Bolen, and engineer Jim Beals. Five prototypes were built, all of which had scalloped fingerboards; the first three never left the factory, and the last two were the only ones equipped with drone strings.
The first drone-string guitar, delivered to McLaughlin in late 1975 or early 1976 and used on his Shakti LP, was made from a noncutaway Gibson J-200 body with maple sides and back. It's lower bout was braced in the usual Gibson fashion (a double X arrangement), and the upper bout had a pair of compression bars - strips of wood (flush with the top) running on either side of the soundhole from one drone-string bridge to the other one. A set of heavy gauge Gibson phosphor bronze strings, approximately .023 to .062, was used for the drone strings. No electronics were built in, though two transducers were added later, one underneath the 6-string bridge and another underneath the drone-string bridge on the lower right bout.
John received his current drone-string guitar in June 1976. It is a refinement of its predecessor, the modified J-200. The body, now cut away for increased fingerboard accessibility, is made of East Indian rosewood rather than maple, and its top-radial fan bracing is patterned after the research of Dr. Michael Kasha, a professor of molecular biophysics at Florida State University in Tallahassee, and Richard
 
Schneider, an associate of Dr. Kasha and consulting luthier for Norlin. (Abraham Wechter is currently apprenticed to Schneider).
A set of Gibson extra light-guage strings (.009 to .038) was used for the six conventional strings; the Kasha bracing helps to project their relatively low output. Whereas McLaughlin's first drone-string had a top of European spruce, the new top is made of Sitka spruce. To enable McLaughlin to pull down as well as push up on the treble strings, the neck was made slighter wider than that of a stock J-200.
The new cutaway guitar has three transducers in all, one under each bridge. They are routed to a connecting box mounted on the tailblock. The box is stereo; one output is the combination of signals from the pickups located under the two drone-string bridges, and the other is the signal from the transducer mounted under the standard bridge. The box is connected to a standard 1/4" output jack, and a cable runs from the guitar to a Frap FS-200 preamp.
The drone strings presented various challenges, since they had to be positioned so as to maintain access to the regular strings; furthermore, Wechter had to develop internal braces strong enough to support the extra tension of 13 strings but flexible enough to avoid interfering with the top's vibration and sound conduction. (Abraham notes that the six standard strings exert about 90 pounds of tension, while the heavy-gauge drone strings add well over 200 additional pounds.) The solution is a network of braces built around a laminated mahogany support block inside the guitar body. The mahogany piece comprises the headblock (located at the neck/body joint); it joins the back and then flares out, gradually thinning, to extend along the underside of the top in the upper left-hand bout.
The bass side drone-string bridge, or tuner bridge (so named because it houses tuning machines for the extra strings), is a shield-shaped piece of ebony actually inlaid into a hole in the upper left portion of the top, rather than glued to the top's outer surface like a standard bridge. This inlaid construction, plus some additional sculpturing, allows the bridge to be virtually flush with the surrounding top, which in turn permits the drone strings to pass under the six conventional strings. "I had to get the action down pretty low," Wechter says, "and there was no way to glue a bridge over the top and still keep the action down, so I actually inlaid it into the top, and it is supported by the mahogany underneath."
To reinforce the tuning pins, a pinblock consisting of a retangular piece of .025" cross-laminated maple veneer was set into a recess in the internal mahogany support block. The pinblock is slightly larger than the area covered by the tuners themselves. After holes were drilled for the pins, the ebony bridge piece was inlaid over the pinblock, concealing it from view. (When wound around the posts, the sharp ends of the strings later began to scratch the surrounding surface, so a contoured stainless-steel plate was installed for protection; it barely extends beyond the area covered by the tuners. Wechter also substituted larger diameter piano pins for the original zither pins, which permits McLaughlin to install drone strings of a heavier gauge.
The saddle slot for the tuner bridge is located just forward of the pinblock, and it extends through the ebony about 3/8" into the interior block. The saddle itself is a straight bar, without notches for the drone strings, and it is made of a 3/8" wide laminate - two bars of ebony with a .095" wide strip of ivory in between. The bridge is sculptured to rise about .060" higher than the top in the saddle area; the saddle's ebony sidepieces are flush with the bridge, and the ivory centerpiece where the strings actually make contact is slightly higher.
 
A hidden Frap transducer is press-fitted into a rectangular notch centered on the underside of the saddle. The saddle's two laminated rosewood feet hold the Frap in place. The pickup's wire extends through a cutaway portion of one of the feet and then passes through a hole drilled in the headblock, extending along the inside rim of the guitar body to the connection box located at the tailblock.
The other drone-string bridge, or anchor bridge (so named because rather than tuners it houses bridge pins that function in the usual fashion), is inlaid in the lower right bout. A 1/2" mahogany support is located inside the body, extending to the corner where the top and rim are joined. A small laminated buttress is glued to the rim from top to back, and it extends inward, underneath the mahogany top brace; to support the ball ends, a piece of maple plywood is also glued underneath the mahogany piece. This small supporting assembly is shaped like a sideways U, with its center fragment, or leg, flush with the guitar body's interior rim, or side. (In fact, the area in contact with the top is substantially larger than the area adjoining the back - just larger than the bridge itself.)
Since the anchor bridge merely serves to hold the drone strings, no tuners where installed and thus no maple pinblock was needed. The saddle and the details of contruction are otherwise almost identical to those used for the tuner bridge. Like its immediate forerunner, McLaughlin's current guitar has two compression braces that run on either side of the soundhole from one drone-string bridge to the other.
Both drone-string Gibsons have unusual fingerboards. The area between each pair of consecutive frets is scalloped, so that from a side view the fingerboard resembles a succession of waves with a fret on each crest. (One of John's current electric guitars, a modified ES-345, also has a scalloped fingerboard; see cover photo.) The minimum thickness of the fretboard at the troughs of the waves is about 1/16". The scalloped construction, specified by McLaughlin, allows him to bend a string by pushing it toward the fingerboard - as well as up and down, parallel to the fret. "The design is extremely effective," explains Wechter, "however, the guitar is exceptionally difficult to play - it requires incredibly good technique. The slightest finger pressure will change the pitch of the strings, so if you're coming into a big chord, you've got to keep the pressure just right - there's no fingerboard to stop you. I've heard John play full chords quickly up and down the neck, but I haven't heard too many other people who can. It's really difficult, but it gives the guitarist a unique freedom and for John it really fits."
The cutaway drone-string has been damaged in various accidents. "In one," Wechter remembers, "the top was mashed, the rim was scarred, and the entire fingerboard had to be replaced. In another one, the neck - a curly maple one from a Gibson Citation - had to be replaced. I used a straight grain maple neck for the new one; the original headstock veneer was salvaged and reused."
Wechter and McLaughlin decided that a guitar whose construction and sound is so unusual deserved to be equally distinctive in appearance. The decorative trim around the soundhole is fashioned from pieces of abalone and Celluloid; the strips along the edge of the fingerboard are Celluloid. "There are more modern plastics used in the industry," Wechter notes, "but Celluloid has a nice grained appearance. The problem is that when you are making white trim, maple or holly or other natural woods don't always look very nice; the only time I would use a synthetic material like Celluloid is for a white trim." A piece of ebony is inlaid into the top near the tailblock and reinforced with an interior sheet of spruce. A stunning bird carved from abalone is set into the ebony.
Having clearly established himself as an innovative luthier and gained some recognition among colleagues for his work on John McLaughlin's radical guitars, is Abraham Wechter now content to rest on his laurels? Hardly: "I am going to start working on a new instrument for John. It was commissioned immediately upon delivery of the second Gibson drone-string - same day. It's tenatively due to be delivered on December 1, 1978, and John and I are doing it independently from the auspices of Gibson. The soundboard design is revolutionary, and I'd rather not talk about it until it is patented, but let me say that it'll be different from every soundboard ever made so far. Just about everything will be new and unusual in this guitar. It'll have a stainless steel fretboard with fitted, pre-scalloped pieces of ebony between the frets, and it'll also have exquisite little drone-string tuners designed especially for me by Helmut Schaller; the tuners will be all you will see on the outside surface. The challenges of building the drone-string guitars put pressures on my mind in a creative sort of way to spring forth this latest development. It forced me into an unconventional line of thinking, and that's where the whole thing came from, really - just being presented with a problem and trying to solve it."
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