The TurboTail
A cost-effective product designed to counter the rotational effect on the bridge due to the pull of the strings. As an educational tool, the TurboTail offers insight into long-held beliefs regarding the soundboard's role in resisting string tension.
The TurboTail
Question: What is the TurboTail?
Answer: According to its inventor, "The TurboTail is a simple, elegant device that diverts the tension of the guitar strings from the soundboard to the structural tail block of the guitar.
All of the vibrations of the guitar strings are still transferred directly to the soundboard to produce sound. But the tension load is diverted to the tail block, leaving the delicate soundboard free to vibrate optimally. The result is that the guitar soundboard can do what it was intended to:
Amplify and temper the vibrations of the guitar strings without having to provide a structural anchor for the strings."
On the 2nd day of February, 2025 I received an email from Reyn Vayda introducing himself and his product.
The TurboTail is available at » TurboGuitar where you can also find several YouTube product demonstration videos.
By simply installing a TurboTail on a Nylon string guitar (equipped with a truss rod), Reyn was able to successfully string up the instrument using a set of steel strings. Those among us who may have attempted such a stunt (with NO modification to the guitar) are all-too-familiar with the severe deformation and/or permanent damage that can result. Repeating his success, he began to modify more of these instruments, reducing fretboard width, lowering action, etc. and placing the guitars in the hands of seasoned players. The reactions were overwhelmingly positive, confirming that when higher tension strings were installed on a guitar built for lower tension strings, but supported by the TurboTail, the guitar appeared to excel in both tone and volume.
The TurboTail was not invented for the purpose of converting Nylon string fan-braced guitars to steel string guitars, but such conversions readily demonstrate the opportunity to re-think the role of the soundboard in today's acoustic guitar designs.
By offsetting the tension of the strings at the bridge of a typical fan-braced, Nylon string guitar, sharing that tension with the frame of the instrument, replacing Nylon with steel strings, observing no negative results and actually garnering favorable response from players, Reyn's demonstrations all but demanded that I conduct my own experiments using the TurboTail.
Traditional and conventional guitar makers, wittingly or not, build in accordance with a simple maxim: The soundboard bracing must provide the much needed structural support to resist the pull of the strings while minimizing such support's negative impact on the vibration of the top. A balance must be struck between being over- and under-built, or overly sturdy and overly fragile.
Guitars built the most structurally sound are generally among the more affordable. By contrast, guitars built the most cautiously and delicately do not typically accompany you on camping trips, safaris or great outdoor adventures. From years of experimentation and at great personal expense I can attest that a guitar sounds its best just prior to (catastrophic failure) coming apart. For many so-called "boutique" builders, the goal has become to build just up to that point of failure and back off a little bit.
The prospect of being able to pay significantly less attention to, if not ignore entirely, the structural role of the soundboard and pursue its sonic potential motivated me to place an order for a half dozen of these fixtures. The TurboTail installs on a completed instrument. I did not wish to build a guitar just to prove this fixture's merits, so I purchased two inexpensive Nylon string guitars for my own testing. My findings, which I have included in this brief article, confirm both the inventor's claims as well as my own hypotheses.
My goal was to establish whether or not I could incorporate the TurboTail into my own steel string guitar builds. I met my goal and set out to design a steel string acoustic guitar using the TurboTail.
My build article is here » The First Turbo Guitar.
A casual observer might confuse the TurboTail with a conventional tailpiece, such as may be seen on an acoustic archtop or Gypsy Jazz guitar.
D'Angelico Archtop
For any who might not be familiar, a tailpiece anchors an instrument's strings to its tail block as opposed to anchoring the strings into or onto the bridge. Tailpieces are commonly found on mandolins and banjos, as well as the bowed stringed instruments, including acoustic upright bases, cellos, violas and violins. The bridges on these instruments typically float (remain moveable) on the surface and are held in place by the downward pressure of the strings.
In order to generate sufficient energy down through the saddle, into the bridge and out onto the soundboard that will result in audible tone, the strings of most instruments fitted with a tailpiece tend to crest the saddle relatively high off the surface of the soundboard. To mitigate collapse of the soundboard from the downward force of the strings, the soundboard is curved, or "arched." This arch is formed either by carving the desired contour from a thicker billet or by bowing, bending or pressing a thinner plate into shape and, if needed, fixing it in place with radiused bracing.
The presence of a tailpiece does not necessitate a floating bridge. Depending on the design, a guitar fitted with a tailpiece may include a fixed bridge (glued-on), as we see in this 1932 Maccaferri tenor (4-string) guitar.
Maccaferri tenor Guitar
In a modern example of an acoustic guitar fitted with a tailpiece and fixed bridge, the Batson brothers addressed all the pertinent issues including string anchoring and saddle torque, going even farther to redesign the soundboard, relocating the soundhole and altering the bracing pattern.
Batson Guitar
If a qualifying factor in the definition of a tailpiece is a "piece" that mounts to the "tail" of the guitar, then the TurboTail is most definitely a tailpiece. However, the difference between a conventional tailpiece and the TurboTail lies in where the strings are anchored. Unlike conventional tailpieces, the TurboTail is specifically designed to work with fixed bridges onto or into which the strings are secured. Two miniature cables tie the bridge to the tail. Unlike conventional tailpieces, the tension on each of these cables is adjustable, individually (attempting to adjust the tension of a conventional tailpiece would simply alter the tuning).
TurboTail Tailpiece
A set of Nylon strings may range from 60 lbs to 100 lbs of tension. The total tension of six steel guitar strings might range between 140 and 190 pounds, depending upon the string gauge. 12-string guitar string tension can exceed 250 pounds, enough to lift your average NFL player off the ground.
Tensioning the strings, tightening them to a desired pitch between the headstock and the bridge, can be visualized as setting up a block and tackle to remove the stump of a fallen tree.
Stump Removal
Just as the stump is not airlifted straight up and out of the ground but, rather, tilts forward under the pull of the cable or chain, so the glued-on bridge of the acoustic guitar typically rotates forward under the pull of the strings. Pull on that bridge hard enough and it is quite possible to complete the analogy with the block and tackle secured to the stump: you can literally tear the bridge (and, in some cases, the soundboard with it) right off the surface of the instrument. I speak from experience, having personally accomplished this feat! Twice!
Bridge torn off the Soundboard
Anchored toward the back of the bridge, the strings pass up and over the saddle on their path up the neck to be attached again at the headstock. Due to this intrinsic lever action designed into the bridge/saddle, its tendency is to rotate forward under string tension.
As repair shops throughout the Earth will attest, if the soundboard and bracing are not deliberately functioning to prevent the front of the bridge from sinking below the surface plane established when the instrument was constructed, the forward rotation of the bridge will cause a depression and may eventually collapse. If the soundboard and bracing provide insufficient support behind the bridge, this same forward rotation will raise the back of the bridge and the soundboard it is glued to will raise right along with it.
The claim that the primary sound of the acoustic guitar is the direct result of the bridge rocking forward and back (ever-so-slightly, but very rapidly) is rather widespread. At one point in my education, I was directly taught that this was the case, and I parroted it. I am no longer convinced and have come to understand the body may work more like a bellows, with the strings moving the soundboard and bridge up and down, albeit rapidly and ever-so-slightly.
The steel string acoustic guitar soundboard is specifically designed to resist bridge rotation, not encourage it. If this small detail is ignored or defied during construction, the bridge along with the soundboard will plunge down in the front and/or tear loose in the back. A function of the bracing has been to transfer some of this torsional force being applied to the bridge to the more rigid sides. In addition to the bracing, a soundboard material's stiffness along with the tension of the particular strings in use determine the degree of forward rotation of the bridge permitted. These factors, along with flexibility of the body, impact the degree of rise in the soundboard behind the bridge, affectionately known as "belly." Bellying should not be confused with a deliberate "doming" (arching, radiusing) of the soundboard, a common practice used to introduce even greater strength to the lightweight top.
Bridge Rotation
Over the last half a century, I have encountered guitars with varying degrees of raised soundboards, or "bellies." Many of them, though not all, sounded great to my ears, seemingly confirming the saying, "No belly, no tone!" I am proud to say that I own some of these instruments. :-)
I have also encountered as many or more guitars with little or no visually distinguishable belly that sounded just as great to my ears. I own some of these instruments, too.
If I think of bellying as a good thing, then I am unlikely to take further action.
If I think of bellying as a deformation of the structure of the guitar then, in lieu of rebuilding my guitar or purchasing a different one, I may seek to counter the effects of bridge rotation.
Severe "Belly"
In the case of severe bellying, short of replacing the soundboard, I may choose to attempt to "flatten" the bulge. I can apply heat and cauls or, even better, heated cauls and use clamping pressure to force the belly out of the soundboard.
However, unless I correct the conditions permitting the bridge to rotate and the soundboard to bulge, I will likely end up having to deal with it, again. To that end, I may choose to explore additional bracing options and/or bridge and bridgeplate replacement. Rarely is this an inexpensive solution.
In November of 1993, Don Kendall patented his apparatus for "reversing or preventing warpage in the top plates of guitars and similar musical instruments attributable to the tensile forces within the strings ..."
"The apparatus employs a compression block attached within the interior of an instrument's
sound box, upon the interior side of the top plate and opposite the bridge, a compression rod between the compression block and the tail block of the instrument, and means within the interior of the sound box for adjusting the movement of the compression rod."
The JLD Bridge Doctor/System addresses the forward rotation of the bridge that is responsible for the "warpage in the top plate", or bellying, by applying a less than or equal rotating force directly to the underside of the bridge in the opposite direction. With a wooden block secured to the underside of the bridge, leverage is used to pry the bridge back into position, accomplished by pushing the wooden dowel back against the tail block. Leverage is adjustable using the set screw housed within the wooden block.
JLD Bridge System
With a JLD Bridge System installed, string energy is still transferred to the soundboard. Mass has been added to the equation. Weighing as much as 34 grams, we have easily coupled the weight of a second ebony bridge to the soundboard. The JLD Bridge Doctor, a "non-destructive" variation of the Bridge System, utilizes 6 brass pins that replace the standard bridge pins and adds 30 more grams to the overall weight, coming in at a total of 60 grams or, using my analogy, the equivalent of 2 additional bridges.
Users of the JLD Bridge System (or Doctor) offer a mix of reactions, with some expressing gratitude for the visual reduction in (if not complete reversal of) bellying, while there are those who claim no reduction occurred. Some users have cited a noticeable increase in bass response, with others claiming they are experiencing more pronounced midrange frequencies. Some say their guitar is louder and others think they may have killed the sound.
I decided to include the JLD Bridge System in my tests, for comparison.
JLD Bridge System installed in a Cordoba C5
The JLD Bridge System (mostly) hides away inside the guitar, and may even be considered completely reversible (if I don't mind adding 60 grams of weight directly to my bridge using a JLD Bridge Doctor).
Unlike the JLD Bridge System, the TurboTail mounts outside the instrument. There is a definite aesthetic to consider, though it is immediately apparent that much thought has gone into the design and appearance of this fixture, making it both functional and attractive. The components of the TurboTail weigh 44 grams, in total. The majority of the weight rests on the tail block, with less than 1 gram being added directly to the bridge.
What does the TurboTail do differently from the JLD Bridge System?
Loose Analogy: Lay a big truck tire flat on a 6 ft. tall platform outdoors between two large trees, and secure the tire to the platform. I trust you can rest the platform on some hard, stable soil. Attach one end of a rope to the tire and wrap the other end of the rope to the large tree 20 ft. away, securing it at a point approximately 5 ft off the ground. Tighten the rope sufficiently to just start to lift the legs on the backside of the platform up off of the ground. Call this setup “My bridge under string tension.”
TurboTail vs JLD Bridge System
The JLD Bridge System directly addresses the forward rotation of the bridge by applying a less than or equal rotating force in the opposite direction. Leverage is used to pry the bridge back into position, accomplished by pushing a dowel back against the tail block. Using my truck tire analogy, bolt a big block of wood, one that will hang 4 ft. below the deck of the platform (like the keel of a ship), to the underside of the platform on which the tire rests. Position a jack between the big block of wood and the tree behind the table (the other tree). Expand the jack and make use of leverage to drive the back legs of the platform down to the ground.
Ta da! The principle works. Rotation has been countered. However, do you notice how both the pull of the rope (strings) on the tire (bridge) and the push of the jack (wooden dowel) on the block are forces working in the same direction? With a JLD Bridge System installed, the soundboard directly in front of the bridge is not just an innocent bystander but, rather, the recipient of these forces.
I have also added weight to the equation. This will lower the resonant frequency of the guitar (shown in my test results). Whether this produces pleasing or displeasing results, a change in tone will definitely occur.
The TurboTail is working the problem differently. Unlike the JLD Bridge System, which is anchoring a lever to the underside of the bridge and literally pushing that lever away from the tail block, the TurboTail is pulling the bridge toward the tail block, directly countering the pull of the strings in the direction of the headstock.
Using my truck tire analogy to visualize this, after removing the jack and the big block of wood that was mounted beneath the platform, simply attach a second rope to the tire on the opposite side of the first rope and stretch it to the adjacent tree, the same one we were pushing our jack up against. Wrap it around the tree at a point 5 ft. off the ground and pull that second rope nice and tight. Watch as the back legs of the platform re-connect with the ground.
As the tests will show, the JLD Bridge System definitely decreases bridge rotation, but it does so at the expense of also decreasing top deflection, the ability of the soundboard to "pump" up and down. Additionally, the JLD Bridge System dramatically lowers the resonant frequency of the soundboard, on which the TurboTail has no effect.
In a head-to-head comparison, the TurboTail has an even greater impact on bridge rotation, nearly eliminating it altogether; nullifying its deleterious effects. Quite surprisingly, the TurboTail actually increases top deflection and it accomplishes this without altering the resonant frequency of the soundboard. These are significant factors to me.
I would consider the TurboTail to be immediately useful for both repairs as well as instrument conversions. I have assembled some of my preliminary thoughts on this fixture in a Question and Answer format, below.
I would suggest trying it and discovering for yourself.
That depends. For my testing I used Nylon string guitars fitted with an adjustable truss rod. Where the TurboTail counters the pull of the strings on the bridge and soundboard, a truss rod assists in countering the pull of the strings on the neck. A normal tension set of Nylon string pulls at 86 lbs. A set of Light gauge steel strings pulls at nearly 160 lbs.
Narrowing the neck, lowering the action and adjusting saddle compensation for improved intonation will definitely make for a more enjoyable steel string playing experience.
The TurboTail really excels at allowing for greater tension strings to be installed on lighter-built instruments (such as fan-braced Classical guitars). It puts a spotlight on how heavily structured our existing Steel stringed instruments are, braced in an effort to resist bridge rotation and collapse.
I don't know. Great strides have been made in perfecting the center soundhole, X-braced soundboard - a nearly 2 centuries old design. Advocates argue, "If it ain't broke. don't fix it." My own interest lies in utilizing the TurboTail in pursuit of an alternate approach to soundboard (and guitar) design.
I would think so, though I have not done this, yet. The TurboTail relies on the structural soundness of the frame of the guitar (the outside edge) to counter the rotation of the bridge. While not required, a carbon fiber rod properly fixed between the tail block and the neck block would go a long way toward ensuring structural integrity over time, especially in the presence of 307.5 lbs of tension (D'Addario EJ86 strings). The neck would likely benefit from increased stiffening, such as is provided by the Dragonplate D-Tube (for example).
The center soundhole X-braced soundboard, introduced in the mid-1800s, quickly became the accepted standard in so-called "flattop" steel string acoustic guitar construction. A few brave souls have dared to challenge the assumption that this approach is the only way to build a quality steel string guitar. While we have access to several examples of successful alternate designs, none have yet succeeded in unseating the center soundhole X-brace design from its dominant position.
Question: What if the need for an X-brace was suddenly removed?
Adding a TurboTail effectively "suspends" the bridge/soundboard above the back. This can be visualized as a stretching of the cable the rest of the way across the ravine, as one would with a Tyrolean traverse, a "Zip" line, or a rope bridge. Imagine the bridge of my acoustic guitar as a deck or platform mounted to the simple suspension bridge in the photo, below, positioned approximately 1/3 of the way across the ravine from the left of the image (beneath the couple shown in the photo). In order to allow the hikers to safely traverse the bridge, and without running a post straight down to the ground below, how much structural support would be required if we were to remove the suspension cables? Applying the analogy to the traditional acoustic guitar soundboard, can you envision the difference?
Suspension Bridge
By sharing the tremendous pull of the strings on the bridge with the frame of my guitar I no longer need to rely on the undergirding of the soundboard alone to handle the load. I can re-focus my attention on its sound generating role.
Soundboard bracing, formerly a catastrophe mitigation requirement, now becomes an exploration in re-directing acoustical properties.
For guitar makers, I consider the TurboTail to be, firstly, an educational tool. Having control over the tensioning of the cables that secure the TurboTail to the bridge, I am free to experiment and explore the relationship between my guitar, as it currently exists, and various string materials and gauges. I can increase string tension with greater confidence.
Going farther, I can re-explore the "flattop" soundboard, as I do not require an arched and braced surface just to mitigate collapse. I can look into reducing the mass of the bridge, reducing (or removing) the bridgeplate, altering my bracing size as well as pattern, even eliminating bracing altogether, as well as reducing the thickness of the soundboard.
The test results that follow provide additional information which may assist you as you draw your own conclusions.
I have tested both the JLD Bridge System and the TurboTail with two brand new, nearly identical Cordoba C5 Nylon string guitars. I have reduced the height of the block of the JLD Bridge System to fit it inside a Classical guitar, reducing its weight from 34 g to 30.5 g (this step would not be necessary in a typical Steel string guitar). For reference, I have included measurements from two additional, unrelated guitars: an un-modified Classical guitar along with an un-modified Steel string guitar.
My tests include the following measurements:
Top Deflection (With 1 Kg weight at the bridge, how much deflection occurs with the strings under tension?)
Top Deflection (With 1 Kg weight at the bridge, how much deflection occurs with the strings de-tensioned?)
Bridge Rotation (With an inclinometer attached to the bridge, how much rotation is measured as the the strings are tensioned and de-tensioned?)
String Height (Between top of the 12th fret and the bottom of the string)
String Height (Off the surface of the soundboard, directly in front of the bridge)
Body Frequency (Air Resonance - T(1,1)1, Open Soundhole, Soundboard coupled with the back)
Top Frequency (Soundboard Monopole - T(1,1)2, Closed Soundhole, Soundboard isolated, uncoupled from the back)
Test l. measures all four guitars, unmodified. The balance of the tests are restricted to the two Cordoba V5s, only.
Test ll. JLD Bridge System installed, Nylon strings.
Test lll. JLD Bridge System installed, Steel strings (Note: I chose not to conduct this test after measuring the significant drop in top frequency associated with the JLD Bridge System).
Test lV. JLD Bridge System removed, TurboTail installed, Nylon strings.
Test V. TurboTail installed, Steel strings.
| TEST | Top Deflection Tensioned | Top Deflection De-Tensioned | Bridge Rotation | 6th String Height at 12th fret | 6th String Height at Bridge | Frequency Body T(1,1)1 |
Frequency Top T(1,1)2 |
|---|---|---|---|---|---|---|---|
| Test l. (No Modifications) | 0.19 mm/kg | 0.20 mm/kg | 1.0° | 3.04 mm | 9.2 mm | 111.3 Hz | 210.0 Hz |
| Test | Top Deflection Tensioned | Top Deflection De-Tensioned | Bridge Rotation | 6th String Height at 12th fret | 6th String Height at Bridge |
Frequency Body T(1,1)1 |
Frequency Top T(1,1)2 |
|---|---|---|---|---|---|---|---|
| Test l. (No Modifications) | 0.12 mm/kg | 0.12 mm/kg | 0.9° | 1.4 mm | 12.4 mm | 95.1 Hz | 167.3 Hz |
| TEST | Top Deflection Tensioned | Top Deflection De-Tensioned | Bridge Rotation | 6th String Height at 12th fret | 6th String Height at Bridge | Frequency Body T(1,1)1 | Frequency Top T(1,1)2 |
|---|---|---|---|---|---|---|---|
| Test l. (No Modifications) | 0.19 mm/kg | 0.20 mm/kg | 0.8° | 3.07 mm | 11.5 mm | 97.5 Hz | 181.0 Hz |
| Test ll. Bridge System Nylon | 0.18 mm/kg | 0.16 mm/kg | 0.5° | 2.79 mm | 11.5 mm | 96.2 Hz | 160.2 Hz |
| Test lll. Bridge System Steel | |||||||
| Test lV. TurboTail Nylon | 0.20 mm/kg | 0.20 mm/kg | 0.3° | 3.07 mm | 11.5 mm | 97.2 Hz | 182.0 Hz |
| Test V. TurboTail Steel | 0.21 mm/kg | 0.20 mm/kg | 0.3° | 3.50 mm * | 11.5 mm | 97.0 Hz | 180.7 Hz |
| TEST | Top Deflection Tensioned | Top Deflection De-Tensioned | Bridge Rotation | 6th String Height at 12th fret | 6th String Height at Bridge | Frequency Body T(1,1)1 | Frequency Top T(1,1)2 |
|---|---|---|---|---|---|---|---|
| Test l. (No Modifications) | 0.18 mm/kg | 0.20 mm/kg | 0.8° | 2.99 mm | 13.0 mm | 97.2 Hz | 181.0 Hz |
| Test ll. Bridge System Nylon | 0.17 mm/kg | 0.16 mm/kg | 0.5° | 2.74 mm | 13.0 mm | 95.9 Hz | 159.4 Hz |
| Test lll. Bridge System Steel | |||||||
| Test lV. TurboTail Nylon | 0.19 mm/kg | 0.20 mm/kg | 0.2° | 2.95 mm | 13.0 mm | 97.1 Hz | 181.2 Hz |
| Test V. TurboTail Steel | 0.20 mm/kg | 0.20 mm/kg | 0.2° | 3.45 mm * | 13.0 mm | 97.0 Hz | 180.9 Hz |
Strings used for testing: D'Addario ProArté Nylon EJ45 (85.85 lbs tension) and D'Addario 80/20 Bronze Light EXP11/XS (157 lbs tension).
Top Deflection is measured with a custom-built gantry using 80/20 Alumin(i)um components, a (modified) Digital Depth Gauge and shop-made wooden parts and secured to the guitar with a Star Tech Wrap N Strap. Weight is provided by a 1 Kg calibration weight (class M1, steel cylinder). The weight is applied, gauge is zeroed, weight is removed and measurement is recorded. Each test is conducted 3 times and averaged.
Testing Top Deflection
Bridge Rotation is measured using a Wixey Inclinometer (Angle Gauge). Strings are loosened, gauge is mounted to the bridge and zeroed, strings are tensioned to pitch and measurement is recorded. Test is conducted 3 times and averaged.
Testing Bridge Rotation
String Height at the 12th fret of the 6th string is measured using a StewMac Nut Slotting Gauge. String Height of the 6th string off the surface of the soundboard, directly in front of the bridge, is measured once using setup blocks and feeler gauges.
* = The installation of steel strings on a Classical guitar bows the neck forward, raising the action. After adjusting the truss rod, the action height returned to the original, unmodified, Nylon string measurements.
Resonant Frequencies are measured using a calibrated miniDSP UMIK-2 connected to a Dell laptop and recorded with REW (Room Equalization Wizard) software. With the soundhole Open, the body resonant frequency is measured as a "coupled" reading (Air Resonance - T(1,1)1) involving both the front and back plates. The soundhole is then Closed (blocked) in an attempt to "uncouple" the front and back plates, "isolating" the frequency of the soundboard, alone (Soundboard Monopole - T(1,1)2).
Testing Equipment
My tests confirm that, with no modification to the soundboard or its bracing and with the TurboTail installed, bridge rotation is nearly nullified and top deflection actually increases. Subjectively, I perceived no change in tone, though the guitars seemed a bit louder to my ears (and to all those who have heard them).
Of greater interest to me is how much more volume is available from a former Nylon string Classical guitar outfitted with a TurboTail and steel strings. Just as sophisticated measurement tools are not required to identify someone shouting versus whispering (especially in a small, enclosed space), so detecting the increase in volume in these "conversion" guitars is unavoidable.
I was not expecting these conversion guitars to so significantly outperform their steel string cousins!
A note regarding forward bridge rotation: The cables securing the TurboTail to the bridge are adjustable in tension, though I have no means of measuring any tension applied to a cable apart from listening to the plink! when plucking a cable with a fingernail. Several days after installation I noticed an audible drop in the volume of the guitar. Upon inspection, I realized the cables had loosened (which I attributed to a tightening of the manually-tied knots at each end and subsequent lengthening of the cables). Upon re-tightening the cables the guitar volume was immediately restored. Very cool! This is not an insignificant issue. I re-measured bridge rotation and the degree of movement had decreased from 0.2° to 0.1°. I assume it could be brought to zero with additional tensioning, perhaps even a negative number, but I have not confirmed that.
A note on volume: In my youth I was told that, when it comes to guitar soundboards, "flatter is louder".
Avoiding a treatise on yet another topic, "loudness" is defined here as perceptible audio volume. Strumming or plucking the strings "harder" typically produces a "louder" sound (within the capabilities of the instrument).
And yet I followed the advice of others and built soundboards with a 25 to 28 foot radius - to mitigate collapse, of course. I suppose I was thinking that, "At least it isn't a 15 foot radius!", or something like that. It wasn't until I spent time with luthier John Greven that I realized I had been ignoring that "flatter is louder" maxim in favor of over-bracing the top. I switched to his suggested 52 foot radius and, what do you know, my guitars got noticeably louder!
Now imagine building even flatter tops using the TurboTail to mitigate collapse. Imagine constructing two identical guitars with only one distinction: one of the guitars requires significantly less energy to produce equivalent audio volume.
I had set out to prove whether or not I could use the TurboTail as a tool to explore the sonic potential of the soundboard by not having to first undergird it with bracing just to prevent failure when subjected to the pull of the strings. Witnessing bridge rotation reduced to zero (or near zero) under string tension, increased top deflection and the undeniable increase in volume on guitars fitted with the TurboTail, I have not only proven that this is the right tool for me to move forward with, but I have also demonstrated that the back and forth rocking of the bridge cannot be the primary driver of the sound, at least, not in the way in which it has been presented across the years.
Building with the TurboTail will permit me to explore completely distinct bracing patterns and entirely new bridge designs.
I would encourage any guitar maker, builder and luthier to play and/or listen to a fan-braced Classical guitar fitted with a TurboTail and steel strings, if only to personally experience the potential of the soundboard. At the very least, for a minimal investment you might gain an impressively responsive guitar! Perform a little saddle compensation to correct the intonation and modify the nut for a more comfortable action. Take it even farther and modify the neck width and depth, if you wish. You may find yourself (as I did) spending significant time enjoying such an instrument.
The TurboTail currently ships with your choice of 2" or 3" tensioning tubes ("wire holders"). I opted for the longer, 3" version. Two miniature ferrules are provided for housing the cable as it exits the surface of the bridge. I chose to forego ferrule installation, opting to drill a smaller hole and permit the wire to directly rest against the wood of the bridge.
The instructions included with the kit are clear and helpful. I have had success with a slightly different sequence of steps, which I will outline here, along with some photos.
TurboTail - What's in the Box?
Apply a piece of tape between the TurboTail and the bridge (see photo, below). Draw a 3" to 4" line on the tape, perpendicular to the centerline of the guitar and 3-1/8" from the edge (for the longer, 3" tension tubes) or 2-1/8" from the edge (for the shorter 2" tension tubes).
Attach the TurboTail. With the guitar stationary and firmly held in place (clamped, vacuum clamped, weighted with pillows, etc), position the TurboTail firmly up against the binding at the tail end of the guitar, centering it on the soundboard (as opposed to the sides at the end of the guitar).
Mark the bottom hole using a scratch awl, set the TurboTail aside and drill a 5/64" hole into the tail block 5/8" deep (you will likely drill all the way through the tail block). Secure the Turbo Tail onto the guitar using one of the wood screws provided.
Using the secured TurboTail as a template for drilling, mark the remaining (top) hole using a scratch awl and drill a second 5/64" hole into the tail block 5/8" deep. Secure the Turbo Tail with the remaining wood screw.
Attach the TurboTail
Locate and drill two 1/16" holes through the bridge, behind the saddle. You are welcome to approximate and drill the holes. However, for best results and to maintain string clearance, a straight wire or wooden skewer (up to 1/8" diameter) may be slid through the respective hole in the TurboTail and used to target the location for drilling (see photo, below).
I opted to follow the suggested hole placement, staying between strings 1 and 2 on the treble side and strings 5 and 6 on the bass side.
Locate and Drill Bridge Holes
Using the supplied length of cable, prepare two sections of cable 12" long. The instructions included with the kit detail the steps necessary to ensure success when working with stranded cable. CA glue must be applied to the wire prior to making any and all cuts in order to prevent unravelling. Bypass cutters are recommended over conventional wire cutters for cleanly cutting cable. I would add that it is advisable to pull the cable taut during a cutting operation to ensure clean cuts. Frayed ends must not be allowed.
Apply a piece of tape to an end of a 12" length of cable. Insert the clean, un-taped end into one of the freshly drilled holes in the bridge, fishing it out through the soundhole. Thread one of the small, flat washers onto the cable. The cable will be secured against the washer by tying a simple overhand knot near the end of the cable. Pull the cable back through through the bridge using the the taped end and verify that your flat washer is making good contact with the bridgeplate.
Slide one of the tension tubes onto the cable, narrow end toward the saddle, threading the cable all the way through the tube. A knot must now be tied in the cable that will secure the cable in the tension tube, allow that tension tube to be attached to the TurboTail AND permit adjustment. We will use the horizontal line drawn onto the tape at the outset of the installation to determine the precise location of the knot. Pull the cable with the tube taut in the direction of the mounted TurboTail to identify the point at which the cable intersects the line drawn on the tape. A marker (such as a Sharpie) may be helpful. Once the knot is tied, trim the excess cable, leaving a short "tail" that will hide inside the tube.
Tension Tubes with Cables Attached
Lastly, attach the tube to the TurboTail using one of the bolts provided and tighten it securely. Repeat the process for the second cable and tension tube. Adjustments to tension can be made at any point after installation.
TurboTail Installed