Here's a design for a modern jazz guitar with a small body. There was a time when archtop jazz guitars were played acoustically. And they were played aggressively too, straining to be heard while laying down the rhythm behind a blaring big band horn section. For these reasons early archtops were big boxes with massive hardware. There is not as much need for loud instruments that can take a lot of abuse these days, which makes things a little easier for the guitar builder. Modern archtops can be made smaller, lighter, and more delicate. And since they don't have to be played acoustically, they can be optimized for their electric tone, even at the expense of their purely acoustic tone. This general trend towards smaller electric archtops has been going on for quite some time. The Girasoli (Italian for Sunflowers) Parlor Jazz Guitar follows this trend.
Initially appeared: July 2, 2003
Last updated: August 13, 2019
The most obvious design features of this instrument are the small body and the offset round sound hole. The body measures 15" across the lower bout, and maintains dimensions similar to those of the classical guitar. Its manageable size makes it quite comfortable to play. The plates are arched to a height of approximately 0.75", typical of modern archtop instruments. The top graduation (a more or less uniform 0.25" thick) and bracing were optimized for amplified tone, even (when necessary) at the expense of acoustic tone and volume. The result is high internal damping and a particularly stiff top. That these qualities should aid in feedback resistance probably makes some intuitive sense, but that they appear to otherwise improve electric tone seems, at least to me, somewhat odd. My preliminary efforts at spectrographic analysis revealed nothing that would indicate why this might be so, and it certainly could be simply a matter of subjective taste. Here's a topic that bears more looking into.
Most of the parameters of a musical instrument are related - it is difficult or impossible to change one without affecting others, and so it is with this instrument. The stiffness of the top allowed the use of a round sound hole. The acoustic tone of a round hole instrument is certainly different than that of an f-hole instrument, but in this case the decision to use the round hole had little to do with the resulting acoustic tone. A round hole allows the use of a bolt on neck joint which aids in the repairability and maintainability of the instrument, thus helping to insure a long and useful life. The bolt on neck part kits offered by lutherie suppliers work well here, or see this page for other sources for these parts. Offsetting the hole Kasha style allows the use of a narrower bracing pattern, which in turn provides better stiffness with less plate mass. The combination produces a very nice modern jazz sound.
Three interesting aesthetic features are the small bass side cutaway, the engraved headstock image design, and the rear-mounted trussrod adjustment nut cover plate. The small cutaway is lined with rosewood. Actually, because it is difficult to bend even thin veneer that tightly, the cutaway simply exposes some of the rosewood neck block, which is lengthened on the bass side specifically for that purpose. The headstock image of three sunflowers was engraved into the headplate using a desktop CNC machine. The engraving was then filled with dyed mastic and sanded back. Then the wood was hand painted using transparent stains. The trussrod adjustment nut cover plate was CNC cut from the headplate and mounts with a single screw from the rear of the headstock.
General construction and materials of the instrument are typical of modern archtops. The top and braces of the guitar pictured are made of spruce, and the back, neck, and ribs are figured maple. Fingerboard and fittings are made of Indian rosewood. The pickup is a very nice sounding Johnny Smith style model from Kent Armstrong. There is an ebony-knobbed volume control set into the finger rest. The top is X braced, but the plans also include a parallel braced f-hole variation for the more traditionally minded. Those interested in building the f-hole version should note that you'll need to make some changes in the way the neck is mounted as it is next to impossible to get at the neck attachment screws through an f hole. A dovetail, tenon, or splined neck attachment scheme would work well here. Or you could follow in the footsteps of lutherie wise guy Rick Turner at Renaissance Guitars and make yourself a long Allen key that would allow you to get at the neck attachment screws through the end pin hole.
I should also point out that there is no reason why this instrument can't be optimized for pure acoustic tone, by making the top more flexible, but if you want to do this I'd highly recommend building the f-hole version. Making the top more flexible with the round hole probably is not a good idea. The resulting top may be too weak to support the string tension.
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