The First Turbo Guitar (in progress)
... ARTICLE IN PROGRESS ...
To my knowledge, this is the first guitar built specifically to exploit the intent behind the creation of the TurboTail fixture.
The TurboTail counters the forward rotation of the bridge by sharing the tension of the bridge-anchored strings with the tail block. You, too, can witness a simple and effective demonstration of its efficacy by installing it on a fan-braced Nylon string (aka "Classical") guitar along with your favorite set of steel strings. While the TurboTail excels at converting inexpensive Nylon string guitars * into impressively responsive steel string ones, that is not why it was invented. I have written about the issues the TurboTail was designed to address, as well as how to install the fixture, and have conducted a series of tests and recorded the measurements in my article, titled » The TurboTail.
For many, the body shape most associated with the steel string acoustic has been the dreadnought. I will be building this body style for my first TurboTail-inspired guitar. Basic features will include an Indian Rosewood back and sides, a torrefied Sitka Spruce soundboard, 14-frets to the body joint, bolt-on neck and 650 mm (long) scale length.
In addition to the TurboTail, visually distinguishable features between this instrument and a traditionally-built dread include the transitional arm bevel, wood binding instead of plastic and a soundport. All of the significant modifications will be inside the box, hidden from view.
* = A truss rod (or equivalent stiffener) is recommended to prevent forward neck bow.
The First Turbo Guitar (in progress)
Stop for a moment to consider: What might an acoustic steel string guitar sound like if the soundboard no longer needed to be so heavily braced just to prevent collapse? We really don't know because we haven't built it, yet. Our lutherie forefathers took us all down a particular path, one that made perfect sense at the time. The ladder braced, gut string lute and its cousins was eventually replaced with the fan braced, nylon string guitar. All was well until someone had the bright idea of replacing the nylon strings with metal. They say the guitar sounded glorious right up until ... oops!
Oops!
Enter the X brace.
No more oopses. Just lots of bowed necks thanks to those metal strings. But they fixed that problem by (eventually) adding metal under the fretboard.
And then there was the bulging belly behind the bridge caused by those metal strings rotating that pesky bridge forward. That worked out, though, as some were able to market bellying as a feature, and others simply started throwing more bracing at the soundboard.
And then there was the ploughing forward of the neck into the body, resulting in everything from unplayable instruments due to such high string action to severe damage of the soundboard at the upper bout. More bracing to the rescue! And we must not ignore all those neck resets, an exercise I was convinced was inevitable on most all acoustic guitars (until I woke up one day). Rather than acknowledge and directly address the source of the problem, two ingenious solutions emerged from the guitar making community: One of those was to perfect the glued-on neck joint, making repair as straightforward as possible. Resets would still be required, but they would be much easier to perform. The second was to replace all that glue and complicated woodworking with metal. Now, with bolt-on, fully adjustable necks, those resets that are still required could be downright enjoyable!
So the guitars got a bit heavier.
All of this wonderful progress continued, undisturbed, for several decades until guitar makers began to seriously reconsider their approach to the staunch, rigid, unyielding builds of the day and set off in search of a more submissive (aka "responsive") instrument.
Like treasure hunters on a quest, this new generation of builders earnestly pursued that perfect balance between structural support needed to counter the pull of the strings and more compliant sound generation. A whole new breed of light-weight guitars emerged, some costing as much as my first house.
And the neck resets and re-adjustments were still required.
And somehow my guitar ended up with a lot more metal in it.
All that metal!
I don't think metal is a bad thing; not at all. I use it, too. But is the amount, location and placement of metal in today's acoustic guitars necessary, all due to a design choice that was made long ago?
If the goal is to achieve an optimally resilient instrument constructed with the least restrictive ("minimally adequate") structure, should we not re-think the design? What if we could revisit that fateful day when the decision was made to adopt the X brace (and all that would accompany it)?
What if we had chosen another path?
Another path?
A 5-gallon bucket of water weighs just under 42 lbs (2-1/4 kg). Imagine lifting one 42 lb bucket with one hand and lifting a second 42 lb bucket with the other hand. You are holding the equivalent of the tension applied by a set of Nylon strings between a Classical guitar's bridge and its headstock.
Now double that load, as you would if you replaced those Nylon strings with a set of light gauge Steel strings. It is suddenly necessary to reinforce the guitar against the added tension, or suffer the consequences. This has been accomplished by installing a truss rod in the guitar's neck and replacing those delicate fan braces with a substantial X-brace and "tonebar" pattern (or equivalent). The purpose of this design is FIRST and foremost to prevent catastrophe. Only then can we talk about SOUND and TONE and esoteric stuff like that.
Now increase that load again! You are in 12 string territory *, where wooden guitars only survive such loads with careful structural reinforcement.
* = D'Addario EJ86 bajo sexto - 308 lbs tension
This load upon the acoustic guitar introduces three issues that plague guitar maker and guitar owner, alike:
1. Forward Neck Bow
2. Neck Block Shift
3. Bridge Rotation
While constructing this conventional-looking acoustic guitar I am attempting to address all three issues while producing a more responsive steel string guitar in the process. I will go into detail for each of the three issues, below, but here is the short version:
1. To mitigate forward neck bow: I will stiffen the neck using a carbon fiber DragonPlate D-Tube from Allred & Associates, Inc.
2. To mitigate neck block shift: I will stiffen the body using laminated linings and carbon fiber rods, as well as add a hardwood veneer to the upper bout of the soundboard and lock the whole thing into the (stiffened) sides.
3. To mitigate bridge rotation: I will rely on the TurboTail fixture by TurboGuitars.
Taking this instrument a step farther, all due to the support afforded me by the TurboTail, I abandon the X-brace pattern entirely in favor of a lightly braced radial pattern. Without the TurboTail, such a lightly-braced soundboard would not support steel strings, at least, not for very long.
If, for some reason, I would later choose to remove the TurboTail, I could always install Nylon strings onto the guitar. Hmm, a Nylon string Dreadnought ... a class-nought or classic-nought? How about a dread-assical?
Let's look at the three issues I more closely and see how I am addressing them in this guitar.
The pull of the strings on the headstock causes the neck to bow forward, if allowed.
A couple of hundred pounds attached to your forehead would apply enough force to bow anybody's neck forward, eventually. If you are determined to prove me wrong at home, give it just a few minutes more and you'll see what I mean.
Mitigating forward bow in the steel string acoustic guitar neck has never been seen as a fools errand, or a solution in search of a problem, or just another unnecessary accessory. I don't recall ever hearing, "Real players go un-trussed", or anything like that. It seems that there has been a consensus from the beginning regarding the need for prevention of forward bow.
An early effort at preventing the neck from curling forward under string tension included a rigid, heavy hardwood beam that was embedded into the neck beneath the fretboard. Eventually, ebony sticks were replaced by various metal "sticks", including square tubes, angle irons and H or I-beams.
Angle Iron Neck Reinforcement
These approaches were not always successful in stabilizing the neck. Once such a reinforced neck was installed, the player got to live with the results. The popularity of rigid reinforcements waned with the invention of the compression rod which, unlike its permanently fixed predecessors, offered some neck adjustability after installation. Like the embedded neck reinforcements they replaced, compression rods also needed to be affixed to the neck, at least partially, and only offered adjustment in one direction (you could only introduce back bow). Compression rods were soon superseded by the advent of the independent machines known as single-action truss rods. These also only introduce back bow, but they do not require embedding one end of the rod within the neck heel; they simple rest in a groove in the neck. Of course, the pinnacle of achievement has been the advent of the dual-action truss rod, a variation of the single action version. Using this machine, the player can curl the guitar neck both back and forward several times a minute, if desired.
Having "been there, done that", I have a different goal, that of preventing neck bow altogether. I have lost interest in providing "bow control". With a nod to the earliest of approaches, yet taking full advantage of modern technology, I prefer to use a non-metal, non-adjustable solution to resist forward bow, a hollow carbon fiber fixture called the D-Tube. I have written this up in an article called » Truss Rod Alternative.
DragonPlate D-Tube
I realize that many guitar makers have never actually repaired (rebuilt, remade, etc) guitars. Not that I think they should have, or should start doing so. But that is how I learned to construct guitars - by learning how to fix broken ones, as well as experimenting with attempts to improve guitars I was dissatisfied with. I learned so much about the forces at work, forces that could destroy an instrument as easily as make it produce gorgeous sound.
Through trial and error - an expensive, but effective education - I found out what happens when guitars are under-braced, or soundboards are sanded too thin, or bridges are attached without sufficient glue, et cetera. I learned about overall string height early on, after shortening more than one saddle and shaving down more than one bridge and KILLING the output on more than one guitar. And then resetting the neck, replacing the bridge with a taller one, adding back the appropriately-sized saddle and Voila! the sound is back! I learned that action should be adjusted using neck geometry, NOT by sanding down saddles. I got rid of the truss rods. I learned lots of things.
But I blew right past all that potential movement of the neck block. It wasn't until about a decade or so ago that it suddenly hit me: Neck resets become necessary primarily as a result of neck block shift. And I can do something about that. Duh!
I have written an article dedicated to this very issue, titled » Neck Block Shift. I encourage you to read it.
The pull of the strings on a guitar neck that is properly resisting forward bow, in addition to pulling the bridge in the direction of the headstock, is most assuredly also pulling that neck forward, directly toward the soundhole (see my illustration, below). Do you loosen the strings each time you set your guitar(s) down, or do you leave the strings tightened? A constant force is being applied to your guitar, whether you are playing it, or it is hanging on the wall, or sitting in a stand, or resting in its case. If that neck block (the bulwark, the buttress, the great wall that stops the neck from intruding into the body) moves (slips, shifts, rotates) even the slightest amount, it will alter the neck geometry, typically resulting in a raised action. Like it or not, you now have an issue with your guitar.
For a very long time, the body of the traditionally-constructed acoustic steel string guitar has been assembled using two (2) thin, bent, solid wood sides that are glued to hardwood blocks referred to as a neck block and a tail block. Kerfing (or kerfed lining) is added to the very edges of those sides in order to have something to attach the front and back plates to. See the photo, below.
Typical Acoustic Guitar Body Shell
Are you aware of just how flexible shells built this way are? Granted, the body firms up when the soundboard (front plate) and back are glued on. But history teaches us that movement will (and most assuredly does) still occur.
Once the body is complete, the neck of the guitar, typically built as a separate component, is attached to the neck block (like the one in the photo, above), using glue or bolts. And the potential for movement of that neck block remains, as is evidenced by the continued need for neck resets/adjustments.
Imagine purchasing a pickup truck and learning that in n-number of years you are going need a truck bed reset, as the back of that truck is not going to remain where it was originally attached at the factory. Better yet, how about being resigned to the fact that your favorite sedan will require an engine block reset after so many miles? What if you were to discover that the wings of aircraft need to be reset, periodically, because they tend to move out of position due to, you know, those tremendous forces being applied to them. Oh yeah, and it doesn't matter how much money you spent on your truck or car or airplane: resets are just inevitable? That all sounds absolutely absurd, doesn't it?
And yet, makers continue to build and players continue to purchase guitars whose necks are not going to stay where they were originally installed. Ladies and gentlemen, this is the result of a design decision. And that is somehow okay because that is how it has been done for decades. I don't know about you, but THAT sounds absurd to me. The neck block should NOT be permitted to move! If my position qualifies me as an iconoclast, then so be it.
There are several ways to prevent neck block movement. On this guitar I combine three (3) approaches to achieve immobility.
My first approach replaces springy kerfing with rigid laminated lining. I epoxy four (4) strips of 1/16" x 1" Spanish Cedar together and press them into a mold. If, like me, you like to add a bit thicker wood binding than is conventional in order to slightly radius it for a more enjoyable playing experience, added depth in the lining will support such an effort. Otherwise, three strips (or less) might be sufficient. After the epoxy dries, the lining emerges as a rigid, unified component that gets attached to the edges of the sides.
Laminated Linings
Traditionally, little attention has been paid to the movement of the neck block in relation to its position within the body. The neck was thought of as a lever, the fulcrum (hinge) being the point beneath the fretboard where the fretboard, neck heel and body all intersect. It was believed that, since the pull of the strings could cause a neck to bow forward, surely that same pull of those same strings must be trying to pivot the fretboard extension down into the body cavity. The Bracing Team responded by adding more support under the fretboard extension. And the need for neck resets continued, regardless.
I fell for this too, back in the early days. It wasn't until relatively recently that I realized that the trouble was with the linear force of the neck pushing forward into the body, not the rotational force (torque). If I could prevent the neck block to which the neck is attached, from ever moving in relation to its original position, then torque would become irrelevant!
My second approach employs carbon fiber rods to tie the neck block to the tail block. The most direct means of accomplishing this, of eliminating rotation of the neck block, is to install one rod near the soundboard and the second rod near the back (this is my preferred approach for my "shoulder port" guitars).
If you run rods directly from the neck block to the tail block, you can leave the soundhole where it is and block (or complicate) access to the inside of the box, if you wish. You can also create an access panel elsewhere, such as via the back or from the lower bout.
Though an even more sophisticated solution can be engineered, securing two (2) rods in this manner can work just fine for offset soundhole designs. For a center soundhole soundboard, such an approach blocks access to the interior of the box. A solution for center soundhole designs is afforded via two (2) additional waist blocks. The resulting "diamond pattern" is a practical means of achieving the stabilization goal while maintaining unrestricted access to the inside of the guitar.
Body Built with Carbon Fiber Rods
For those who fear or worry that the linear force applied to the neck block is being transferred to the waist and will now blow out the sides, please pause long enough to take a glance at your favorite acoustic guitar. You probably own, or play, or are building guitars with extremely flexible shells, and rely solely on the front and back plates to stabilize the flex. And you have been fine with that up until I just brought it up. Those same two (2) plates are going to be added to this guitar and they will prevent the sides from blowing out.
However you choose to design your guitar, focus on eliminating flex. Prevent the neck block from shifting.
My third approach involves reinforcing the upper bout of the soundboard by applying hardwood veneer whose grain is oriented perpendicular to the soundboard's grain. Once the bracing has been added, that thicker section of the soundboard is "let in" to a recess in the shell, locking it in place. This approach has proven quite effective on many guitars I have built. With the advent of the TurboTail, is it actually necessary? We will visit this again, later.
Body Shell and Soundboard
The pull of the strings on the bridge causes it to rotate forward, pulling the soundboard behind it upward. This usually results in a depression in front of the bridge and a bulge, affectionately called a "belly", behind it. The degree of deformation your guitar is subjected to is directly proportional to how it was constructed for the forces it will be subjected to. Belly can be mitigated by increasing stiffness in the soundboard to which the bridge is attached, as well as by minimizing string tension using shorter scale lengths, extra-light gauge strings, etc. So, you can simply leave the soundboard a bit thicker, increase the radius (arched dome) and the enhance the bracing. Problem solved, right?
Well, it depends on who you ask and what you (and they) are willing to settle for. We all accept that a lot can be accomplished with adequate bracing.
Steel Girder Bridges
The proverbial elephant in the room is the issue of relying on the soundboard for structural support. A chair maker sets out to construct a sturdy chair, one intended to support a LOT of weight. Making that chair comfortable, let alone designing it to be aesthetically pleasing, is secondary to ensuring it does not collapse when sat in. Chair makers do not rely solely on the chair seat for structural support. And making that chair musical is completely outside the skill set of the seasoned chair maker.
Likening a chair maker to the modern acoustic guitar maker may certainly feel a bit irksome, but permit the analogy long enough to see the intrinsic flaw, if not the "silliness" of assigning the task of structural support to a thin wooden plate that is not a chair seat. Ironically it is called a soundboard, yet the maker of the instrument only gets to live with the sound of the board as it presents itself AFTER the reinforcement tasks are fulfilled. Can you see how a luthier's skill is kind of relegated to "tone recovery" efforts?
I have not set out to cast aspersions on the veracity of traditional lutherie (well, maybe a little). I fully acknowledge that a new generation of builders have earnestly pursued that perfect balance between structural support and sound generation. I own, have played and have heard some really impressive examples.
I contend that, when building today's steel string acoustic, we have settled for a compromise between the structural support needed to prevent collapse and the lightest possible build to generate the most pleasing sound(s), all due to the belief that structural support is the role of the soundboard. Builders must lean a bit more towards the structural integrity side of things due simply to good business principles when dealing with consumer goods (aka "warranty claims"). Building "lighter" typically translates to "more fragile" and "more expensive". Progress-wise, we have pretty much boxed ourselves into a corner as the result of a design decision made decades ago.
Most players and builders are no doubt aware of the mystique of certain "pre-war" Martin guitars. If you have not experienced holding one and playing one, then live vicariously through the justifiably exaggerated emotional outbursts from those of us who have. There is no question: some of these are impressively sensitive guitars that literally quiver in the presence of ambient noise. Brushing across the strings can be something of a meta-physical experience. If you can find one available for purchase, be prepared for a hefty investment.
Pre-war Martin ($250k)
In more recent years, several so-called "boutique" builders have produced similar creations. In addition to generating delightful sound and being very expensive, all of these guitars share something in common: they are extremely delicate instruments. They have been built as lightly as possible while retaining just enough structural integrity to not collapse, at least, not yet. Can we agree that these instruments, both old and new, both vintage and current, are all held in high regard?
So the summit (the peak, the top of the mountain, the best-of-the-best, the crowning achievement of acoustic guitar auditory perfection) is definitely out there - for a price, right?
But these are NOT the guitars that the average guitar player plays! Nor are these the guitars we typically associate with our favorite artists. From all those great recordings and all those awesome live concerts, the sound we all (or most of us) have come to expect from the acoustic steel string guitar (apart from that often actually being the sound of the pickups and electronics used, but I digress), is rarely, if ever from this level of perfect instrument. In fact, the instruments we are hearing played by our favorite performers are often well below this level of instrument.
To summarize: The very best guitars ever made, the most "responsive" ones, the ones we claim have achieved that critical balance between structural support and weight, are 1.) Unaffordable by all but a few. 2.) Require extra care and feeding as a result of the compromises made during construction and 3.) The sound(s) we most commonly associate with the acoustic guitar typically aren't even from these guitars.
Why not revisit that fork in the road, that decision to apply even more structural support to the so-called "soundboard"? Why not try something different?
With the body properly "rigid-i-fied" I can now begin creating the soundboard for this guitar.
Having tied the neck block to the tail block using carbon fiber rods, and knowing I will be adding a TurboTail, is any bracing even required? It may not be, but this is not the guitar I am ready to go quite that far with.
I could populate the soundboard with a scaled-up Torres-style fan bracing pattern, and I know the guitar would be functional, but I have something slightly different in mind.
Earlier, I mentioned adding a 1.5 mm thick Mahogany veneer to the soundboard in the area of the upper bout. The veneer accomplishes several things, including supporting the soundboard, structurally, right where I am going to be cutting a giant hole out of it. It gives me a larger surface (thicker "edge") to attach the soundhole binding to and it assists in stabilizing the upper bout against neck block shift. I have had such success with this approach that I am hesitant to eliminate it from my builds, at least not completely, not just yet.
I am adding a small, quasi-isotropic, carbon fiber plate, 1.5 x 20 x 90 mm, in lieu of a wooden bridgeplate. Using carbon fiber as a bridgeplate is not new to me, but making one this small is. I am planning to attach a JME Ultra Tonic pickup directly beneath the saddle path, and this plate does a great job transferring the string energy. Let's see how well the smaller bridgeplate performs on this guitar.
The hand-split Sitka Spruce braces are 6 mm in width by 7 mm tall. The miniature precision joinery that ties everything together may well prove to be totally unnecessary. But who's to say? This is the exciting world of experimentation and it is enjoyable for me to do.
Bracing - A Whole New Take on my Bridgeplate
Two lone braces will run from the shoulders of the upper bout to the front of the (miniature) bridgeplate. I am not convinced these are necessary, either, but I am inspired to try this pattern. If you are wondering where all the rest of the lumber is that you are accustomed to seeing added to the upper bout of the soundboard, the transverse brace, the "popsicle" brace, the wing grafts, etc, please read my article » Neck Block Shift.
The balance of the braces will "fan" out from the sides and back of the bridgeplate. Note that these braces are intentionally decoupled from one another directly below the bridge, meaning that a single brace does not pass from one side of the bridge to the other, as is common in an X-brace design. All of these braces are solid Sitka save one. The curved brace is a Spanish Cedar laminate, borrowed from the laminated linings. Is it absolutely necessary? Who knows?
Tape is applied to keep the soundboard as clean as possible, free of adhesive. I have pre-shaped the bottoms of the numbered braces to match the slight radius I am adding to the lower bout. The upper bout remains flat.
Taped for Adding Braces
Glue is applied and the braces are set. Go-bars hold the braces in place while the glue dries. The tape gets removed at the appropriate time and what remains is a neat and clean soundboard.
I fully acknowledge that all of this is highly experimental. I am recording my layout, placement and measurements for comparison with my next experiment.
Braces in Go Bar Deck
After the glue dries the braces are shaped to remove "unnecessary" material. Again, who knows how much brace material is required, if any? My premise is that the stabilization of the neck block within the body and the countering of the bridge rotation afforded by the TurboTail relieve the need for structural reinforcement of the soundboard. I am adding bracing, albeit ridiculously minimalistic based on traditional steel string build standards, as a matter of familiarity, as a point of reference for the next build, which I expect will be different.
Shaped Bracing
You may have noticed a change in the perimeter of the veneer on the upper bout from the previous photo. Rather than attach two (2) layers of veneer and inset the entire upper bout, as I have done on my previous builds, I built up one (1) small additional layer of (cross-grain, yet again) veneer at each waist in order to act as a "key".
I remove corresponding material from the sides to form the "lock".
Soundboard Keyed to Body
It is rewarding when the parts align perfectly. Regardless of how this guitar sounds, at least we know it will look fabulous on the inside! :-)
Precision Fit
Before I attach the soundboard, I want to add some decor to the perimeter of what will become the soundhole. This step is typically performed prior to adding bracing, while the soundboard can be laid flat against the bench. Because I add a veneer and can keep the upper bout flat throughout the process, it is just as easy to wait until this stage to add rosettes, purfling, inlay, etc.
With a thin backer board secured to the veneer, I can safely cut out the soundhole.
I add some binding to dress up the appearance. Don't hold me to it, but I think I see a theme emerging.
Turbo Guitar Theme
I have a bit more work to do before I can assemble the body. First up, I need to brace the back. Nothing radical is planned, in that I am applying four (4) Spruce braces, ladder style, to a thinned Rosewood plate. What may be a bit unusual is that I am forcing this back into a 15 foot radius, rather tight for a dreadnought. The braces are slender at 6 mm (1/4") thick, and I will keep them rather tall, 17 mm (11/16"). Additionally, I will not be running these braces all the way into and through the rims, but am stopping them just shy of the inside edge.
Back Bracing
Shaped Back Bracing
Glue the soundboard and the back to the body shell. How hard can it be, right?
For guitar bodies built independent of the neck (no Spanish Heel), it is common procedure to attach the back first. This allows unrestricted access to cleanup glue squeeze-out, focusing on the area of the back most-oft viewed through the soundhole after the guitar is completed. Once the back is attached the soundboard is then laid face down on the bench and the back and sides, as a unit, is glued to it. At this point, any glue squeeze-out is whatever it is, as it is only viewable with mirrors or scopes.
I am reversing those steps with this guitar, as there are a couple of details that I want to address before closing up the box, and I want to be able to see what I'm doing as I do it. I am adding a small carbon fiber plate near the neck block. Instead of gluing the fretboard extension down to the soundboard, I will merely secure it with two (2) small bolts. Because I have already added a hardwood veneer to the upper bout of the softwood soundboard, the carbon fiber plate is not technically necessary. My reasoning for adding it is that it brings integrity to an area subjected to strong forces, as well as appears to excel in vibration transmission. We'll see.
This is also the time that I will add the pickup to the bridgeplate. I intend to experiment on another guitar on whether or not a bridgeplate is even necessary when building with the TurboTail. For now, having this carbon fiber plate reside where I will be attaching the TurboTail cables bolsters my confidence.
I want to pay extra attention to the coupling between the soundboard and the linings, and this approach lets me do just that. With the soundboard attached, it is starting to resemble a guitar, don't you think? More importantly, it starting to sound more like a guitar, as you might expect from such a lightly-braced top.
Soundboard Attached
Most players by now have realized the personal benefit of having a soundport on an acoustic guitar, as they are able to better "hear" what their audience "hears". The sound of the guitar is "ported" to the player as well as the listeners.
There is, however, an additional benefit a soundport can provide. Permitting more air to move freely in and out of the box (or "sound chamber") of the guitar can contribute to an improvement on the instrument's overall sound. A very efficient way to accomplish this is to simply enlarge the center soundhole. That works great, but tends to look a bit strange, as we have grown accustomed to seeing 4" circles in proportion to the outline of our modern guitars. A soundport also accomplishes the task, though it requires a little more effort to create. It is not required, but may be advisable to apply backing to the solid sides, as opposed to simply cutting holes through the thinned wood. I arrange and glue in cross-grained veneers for extra support. Color and material choice adds a subtle aesthetic.
Soundport
I am installing an Ultra Tonic soundboard transducer from James May Engineering to the carbon fiber bridgeplate, directly beneath the path of the saddle. Installing the pickup at this stage requires knowledge of where the saddle will be once the bridge is installed, so it is a commitment, but it makes for such a clean install.
Additionally, I am accommodating the installation of a Sunrise magnetic soundhole pickup. I am adding the Sunrise connector to the JME Ultra Tonic endpin jack. A standard mono cable will carry the Ultra Tonic signal as the primary pickup. A stereo cable will permit both the Ultra Tonic and the Sunrise signals to be controlled, independently.
Pickups
Only now can I safely glue the back on to the body and trim it flush with the sides. Prior to putting in the effort to add rigidity to the body of my guitars, gluing on a soundboard or a back required the shell of the body to be held firmly in the body mold (form), the same mold used when the sides are joined with the neck and tail blocks and when the linings are added. Neglecting to use a mold during this critical period of alignment could result in a rather misshapen body (should you encounter a guitar that you cannot rest on its side on a flat surface without it rocking, you may have an explanation as to what went wrong and when it may have occurred).
A side benefit (pun intended) of using a body mold to join the plates is one of registration. Tabs may be added (or not removed until completion) to the soundboard and/or the back that align with marks or holes in your form. Depending on how precise your registrations are, and how faithful you were to rely solely on those registrations during the build, closing the box can be a bit less fiddly. Without registration tabs and a form to pin them to, glue-ups rely on things like {gasp!} manual dexterity, visual acuity, patience, skill and crazy, old-fashioned stuff like that!
As expected, there are no issues with this guitar. Thanks to the laminated linings and the carbon fiber rods, the body squares up quite nicely outside of the mold and the center seams of the front and back plates line up just beautifully with the center seams of the sides.
Box Closed - Back
Box Closed - Front
I need to pause the build and make up some decorative binding. I'll return to cut the binding and purfling rebates (rabbets), and install the trim.
I do not believe there is anything noteworthy about the binding.
I learned to make the transitional arm bevel directly from the luthier who developed it, Kent Carlos Everett (now retired), in his shop. His approach, distinct from the approaches of both Grit Laskin and Kevin Ryan, involves pre-shaping the side, adding the bevel blocking then shaping it, shaping the soundboard prior to attaching it, splitting the binding and purfling at the bevel, to be rejoined on the opposite side, re-building sacrificial soundboard outside the purfling, shaping the bevel and, finally, adding the veneer.
Since then, I have modified the technique, slightly. I pre-shape the bevel block prior to attachment. I no longer pre-shape the soundboard but, rather, attach a soundboard having full dimensions. I cut the purfling channel into the soundboard, staying within the boundaries of the bevel block (for obvious reasons). This eliminates having to build up sacrificial soundboard outside the purfling, as it already exists.
My necks make use of the carbon fiber DragonPlate D-Tube by Allred & Associates, Inc. I have not found a headstock on a neck fitted with a D-Tube to benefit from any additional support (such as a scarf joint, or a backplate) in order to strengthen what would otherwise be the weakest area of an acoustic guitar. The way I install it, the pultruded D-Tube spans that narrow section of wood just above the nut, supporting it against breakage (should the unthinkable ever occur).
Attachment, shaping, headstock, mono-scale fretboard, nut
Pore filling and finishing
Pinless bridge and compensated saddle
How does it sound?