Guitar Shop 101: Installing an EVH D-Tuna on a Floyd Rose

A few months ago one of my favorite clients brought in a very cool project. He wanted me to install an EVH D-Tuna (Photo 1) on his Floyd Rose-equipped Peavey V-Type Limited Edition. Designed for double-locking tremolo systems, the D-Tuna lets you quickly lower your bottom E string a whole-step to D without having to unlock the string nut, retune, and then lock the nut again. Now that’s handy!

D-Tuna details. The device works with standard electric string sets and in either concert or Eb tuning. (In the latter case, the dropped 6th string goes to Db.) The kit includes two locking screws of different lengths; this allows the D-Tuna to work with most Floyd Rose or Floyd-licensed double-locking trems, such as the Peavey unit in Photo 2. Once the spring-loaded device is installed, you simply press it down to drop the low E string to D. To raise the 6th string to E again, push the D-Tuna towards the bridge—it’s that simple.

The D-Tuna has been around since the early 1990s and it’s relatively easy to install. But it does require one very important modification: For the D-Tuna to work properly, the tremolo has to be blocked to prevent the rear end from drawing back toward the body. (On the D-Tuna website, this is described as “stabilizing” the bridge.) This mod requires installing a small wooden block inside the spring cavity between the Floyd’s inertia block and the body, as shown in Photo 3. This block, or shim, resides on the spring side of the cavity.

The rest of the project is rather routine: replace the string-lock screw, install the D-Tuna, tune the guitar, and finally adjust the intonation. Let’s go through each stage of the process.

Preliminary setup. Before I install a D-Tuna, I make sure the guitar’s action is adjusted to match my client’s playing style. In fact, I like to give a guitar a thorough setup before installing the D-Tuna. For a detailed description of the process, check out “How to Set Up a Floyd Rose-Style Trem” on premierguitar.com.

Blocking the tremolo. Once the action is adjusted, it’s time to block the tremolo. This is to prevent the inertia block from drawing toward the spring claw after you’ve dropped the low E a whole-step and reduced string tension.

The best way to do this? Carve a slim wooden shim to position between the Floyd’s inertia block (where the springs attach to the trem system) and the edge of the spring cavity. I like using maple for this because it’s so durable. The tools are simple—you can use a small hobby saw and a belt sander or a few sheets of medium and fine sandpaper—but it takes time to measure, cut, shape, and fit the shim, so be patient.

And here’s an important detail: I recommend sizing the shim so it’s level with the body at the edge of the spring cavity. In other words, avoid using a shim that extends as far as the inertia block, as this can cause the springs to bind on the shim and create tuning issues. (Refer to Photo 2 again to see how the shim stays level with the body.) Another reason to use a shim that’s shorter than the Floyd block: You want to be able to raise or lower the bridge to adjust the overall action without dislodging or bumping the shim.

As you shape the shim, make sure the tremolo base remains level with the guitar top when the strings are tuned to pitch. Unless you’ve made a few of these shims, assume that the fitting and shaping will take several passes, and it’s crucial to retune to pitch each time.

Once the shim is installed and the tremolo is level with the body, you’re ready to secure the shim to the edge of the spring cavity using medium viscosity super glue. I don’t recommend attaching the shim to the inertia block.

After you’ve glued in the shim, check the tremolo for any slack. If the bridge tail can draw back, you may want to tighten the screws on the spring claw to eliminate this slack, but be sure that the tremolo remains level with the guitar body.

Adjusting intonation. Next, use a high-quality electronic tuner to check the 6th-string intonation at the 12th fret one more time. In fact, I like to check the 12th-fret intonation with the string first tuned to E and then retuned down a whole-step to D. If the fretted note is sharp relative to the 12th-fret harmonic, move the saddle back (away from the neck). Conversely, if the fretted note is flat compared to the harmonic, move the saddle forward. Most Floyd Rose systems use a 2.5 mm hex key to unlock the saddle’s set screw.

Installing the D-Tuna. Here comes the easy part! Unlock the 6th string at the string nut and slacken the string with the headstock tuner. Remove the 6th-string locking screw at the bridge (Photo 4) and replace it with the D-Tuna device. Typically this requires a 3 mm hex key.

As I mentioned earlier, the D-Tuna ships with two different length screws for attaching the D-Tuna to the bridge. Photo 5 shows the original screw (top) compared to the longer replacement screws. Choose the replacement screw that gives you enough room to fully disengage the D-Tuna and thus drop the low E to D. For this guitar, I used the shorter of the D-Tuna screws.

First, slide the D-Tuna spring onto the screw, and then slide the knurled unit onto the screw. Photo 6 shows the spring and D-Tuna installed on the new locking screw. Next, insert the locking screw into the bridge saddle and tighten it as usual.

Now, back the 6th-string’s fine tuner all the way out, and then set it so it’s barely touching the replacement screw. Then, with the D-Tuna pulled out—disengaged—tune the 6th string to D and lock down the string nut. In Photo 7, the D-Tuna is installed, but disengaged. Using the Floyd’s fine tuner, tune the 6th string to D.

Test the unit by pushing the D-Tuna towards the bridge, fully engaging it (Photo 8). This should retune the 6th string to E. At this point, use the kit’s included wrench and D-Tuna’s set-screw adjuster to fine tune the E.

Next push down on the D-Tuna to disengage it again and check the tuning to make sure it’s at D. I recommend you do the majority of your D tuning at the headstock, rather than using the Floyd’s fine tuner. Sometimes the fine tuner will shift slightly when you use the D-Tuna, but backing the fine tuner all the way out prevents this from happening.

With a little practice, you’ll find that using a D-Tuna is pretty simple, and you’ll be able to incorporate dropped-D riffage into your music whenever you get the urge.