Replacing a Bridge P-90 Pickup With a Humbucker in Epiphone Les Paul Special — Routing 101 | DIY
I’ll demonstrate by converting part of a new guitar into sawdust and noise, then transforming the instrument by installing a totally new pickup in the bridge position—so we can retain the natural flavor of the P-90 in the neck, but goose up the bridge position with a humbucker. And to make things even easier, there is a video of me doing this mod online at premierguitar.com, which I highly recommend watching. In it, I explain every step in great detail.
The guitar is a brand-new Epiphone Les Paul Special finished in glossy TV yellow—in my opinion, the best furniture finish ever commandeered for broadcast purposes—loaded with two P-90 pickups, black plastics, and chrome hardware. The pickup going into this guitar is a Parsons Street Humbucker by StewMac. Designed to emulate a popular variation of the traditional PAF-style humbucker, this medium-output pickup should retain plenty of treble clarity. It will mount to the guitar with a classic black humbucker mounting ring.
What You’ll Need for This Mod
Besides a guitar, a small bandsaw for cutting the pickguard, and painter’s tape, you can pick up everything you need for this modification project online at StewMac.com.
• Bosch Colt 1 HP Variable-Speed Palm Router
• Bosch Plunge Base for Palm Router
• Parsons Street Humbucker
• Fisch Wave Cutter Bit 5/8"
• Amana Tool Carbide Tipper Router Bit 1/4"
• Humbucker Pickup Routing Template
This is what our project guitar looked like before it hit the workbench.
Since we are on the topic of pickups, I’d like to note that the acronym PAF does not define a specific sound or a strict recipe for pickup making. It is simply a description of a design—Patent Applied For. Both P-90s and PAF-style humbuckers actually have a lot in common. If you examine their construction, it seems the goal for PAFs wasn’t necessarily a different-sounding pickup, just one that didn’t hum like its single-coil predecessors.
The OEM pickups in this Epiphone Les Paul Special are quick-connect, which makes for easy disassembling, but will require trimming the connectors and soldering as part of the humbucker’s installation.
As a result, a lot of the early Gibson ’buckers and P-90s have comparable output and not entirely dissimilar frequency response, depending on their magnets and how the coils were wound. These factors varied quite a bit for the first few years of production and produced some very different sounding pickups.
But, back to the bench, focusing on the task at hand.
Our author holds a StewMac humbucker-sized routing template over the pickup to be replaced.
This guitar is a good candidate for this kind of pickup swap for a few reasons: One, we only have to modify an existing pickup cavity; two, a medium-output bridge humbucker such as our Parsons Street should complement the sound of the neck P-90 nicely; and three, while the modification will be obvious, this new pickup will also complement the classic looks of the guitar.
The pickups are mounted to the body via two easy-to-remove screws.
You may be here looking for inspiration as much as information—thinking about trying this modification yourself, but still not sure. Although it’s ultimately your decision, I can at least equip you with some arguments for and against.
Try the mod if:
• You are curious about how different pickups sound and you recognize the benefit of using the same guitar as a control in your experiment.
• You love everything about your guitar, but want a little more punch from the bridge pickup. This is common with single-coil pickers, Telecaster aficionados excluded.
• You might deem the guitar cooler this way. After all, it’s an uncommon but highly effective treatment for this model—which could make you want to play it more.
Don’t try this mod if:
• You have a more valuable, historic, or rare instrument.
• The resale value of the guitar matters to you.
• It’s not your guitar (LOL).
• Safety and preparation are not priorities.
Don’t Fear the Router
The part of this modification that scares most people off is working with a router. It’s an intimidating device and fear of it is understandable, considering what it can do to a guitar, or fingers, but learning about how it works and how to use it should, hopefully, alleviate your fear.
A router is a powered chisel that does what a standard chisel can do, good or bad … only faster. Positive or negative results depend entirely on the operator, just like any hand tool. And good results come from developing good technique and practice, which is one of the skills this mod aims at developing.
There is a wealth of information available about technique and a limit to the length of this article, so I’m only going to focus on a few basic tips that will help you get started safely:
• Only power the router on or off when the bit is able to turn freely, not in contact with any material.
• Do not move the router while the bit is accelerating or decelerating.
• Multiple shallow cuts are better than one deep cut.
• Pay attention to the router bit’s direction of rotation when planning the direction of the cut.
• Use PPE—at the very least, safety glasses.
Now we can get started with the project. However, there are several things to do before we can begin making sawdust and noise.
If you’re just too excited about firing up the router and can’t wait, I understand, but please read through these steps first. Afterwards, feel free to practice some small shallow cuts on the edges of scrap wood before jumping into the project, using large enough pieces that can be secured to your work surface. This will give you a good idea of how the router feels and sounds when making a cut.
Step 1: First, all electronics and hardware should be removed from the guitar, to make sure we have plenty of room to operate the router without any obstacles. Take photos and draw diagrams now if you’re unfamiliar with guitar wiring, since you will probably have to disconnect the pickups and switch wires, and will definitely be connecting the new pickup. [Marshall provides instructions on this step in the video companion to this story on premierguitar.com, and StewMac has detailed wiring instructions on its website.]
Note that on this guitar, although the pickup selector switch is not in the way, I suggest removing the switch to keep the wires away from the router bit.
Step 2: Next, make sure the new pickup fits inside the template for the new pickup cavity. Make sure you have enough clearance to move the pickup through the template. It shouldn’t catch or rub on any part of the template.
Line up the template on the guitar body to determine where the new cavity will be. There are several techniques you could use here. Some might locate and mark the guitar’s center line, then line up the template that way, but since we are modifying an existing cavity we know is more or less centered, I suggest using that cavity as a guide and eyeballing it. Carefully.
Since the StewMac template has a center line and other measures on its face, it’s easy to position over the cavity for the OEM pickup and decide which of its zones need routing.
Step 3: Now that you know where the template goes, attach the template to the guitar. I prefer using rolled up painter’s tape on the bottom side of the template because it holds fairly well (as long as you don’t use too much force with the router), it’s easy to remove, and relatively safe for modern finishes. Stronger double-sided adhesives work well but run the risk of damaging either the guitar or the template on removal.
After taping the template in place, Marshall uses the router bit to trace the path he’ll use, and to gauge the depth of the pickup cavity versus the location of the bit’s bearing.
Step 4: The template determines the shape of the new cavity, but the router itself determines the depth of the cut. Start by setting the depth so that the tip of the router bit is just barely touching the bottom of the cavity when the router is sitting on the template. Once the cut is made, we can double-check to make sure this depth works.
With the template secured and the depth of cut adjusted, I suggest trying a “dry run” of the cut to make sure the router moves freely around the template. Keep in mind the bit’s direction of rotation and plan moves that allow the bit to cut into the wood—but don’t do it yet. Just outline your moves. Make sure that the bearing on top of the router bit can freely follow the template, too. Setting the depth too shallow risks cutting your template, ruining both it and your guitar.
This seems like an excessive amount of preparation, but trust me, an hour of planning can prevent a minute-long job from destroying your guitar.
It’s almost time for the fun part. Don’t turn the router on yet. Put on your safety glasses and consider using ear protection if you are sensitive to high-pitched, loud sounds. This would also be a good time to make sure you have a shop vacuum handy, as you are about to make quite a mess.
Step 5: Now, it’s time to actually make the cut. Tilt the router slightly so that the bit is completely free before turning the router on. Keep in mind that the router should not be moved while the bit is accelerating or decelerating, so don’t make any cuts until the router is at full speed.
Once it’s at full speed, make the cut as practiced earlier. Take several shallow passes instead of trying to remove all the wood at once. There’s no need to force the router, you will hear and feel when the bit is cutting. Too much force may cause your template to move and ruin your cut, wreck the router bit, or potentially hurt you. And since the router spins the bit in a specific direction, be sure the cutting edge of the router is digging into the wood and that you move the router in the direction that puts the blade edge of the bit forward.
Now, you can turn the router off, but remember not to move it until the bit has completely stopped rotating. Check that the template has not been damaged, that the cut matches the template, and the pickup fits neatly inside.
The sawdust flies as Marshall uses the router to slowly make gentle, shallow cuts, eventually reaching the cavity size required for the Parsons Street Humbucker.
Step 6: With this specific type of pickup, it turns out that we do need to make two slightly deeper cuts to accommodate the mounting screws and “ears” of the pickup base. You can do this by setting the bit to cut just a little deeper—in our case about 3/16" deeper—and cut only the areas around the pickup mounting screws. You could also do this with a hand drill or a drill press and a large spiral or Forstner bit, but I prefer the cleaner results from the router.
Checking the final cut to be sure there are no issues like snags or protrusions that would interfere with the fit of the pickup.
Step 7: Now, the new bridge pickup should fit. Test it by mounting the pickup in its ring and placing this assembly on the guitar. The mounting ring should sit on top of the guitar without having to force it down. If everything fits, go ahead and rewire and reassemble the guitar, then set it up to your liking. [We have a video at premierguitar.com called DIY: Easy 4-Step Guitar Setup.]
After placing the ring around the pickup, Marshall drops the humbucker and ring into place to test the fit. (As it turned out, a little bit of additional routing was required for the bottom of the cavity, to provide space for the humbucker’s left-side dog-ear mount.)
Step 8: On this Les Paul Special, since I’ve replaced the bridge P-90 with a bigger and more squared-off pickup mounting ring, the pickguard will have to be modified slightly to fit. I did this by tracing the pickguard onto a piece of paper, taping the tracing to the guitar, then marking the outline of the new pickup mounting ring. Now, I can use the tracing as a template and cut away the parts of the pickguard that I don’t need. I used a small bandsaw blade to cut away most of the material and slowly fine-tuned the edges with files and a small scraper until it fit.
Here’s the paper template Marshall used to trace the new pickguard configuration required to accommodate the Parsons Street Humbucker. He then placed it atop the actual pickguard to make the cut.
I like to start with my bridge pickup very close to the strings, somewhere around 3/32" away from the treble strings and balancing the bass side of the pickup by ear. After that, I like to set the height of the neck pickup just by comparing the sound of each pickup, again, making sure that the output of each pickup is balanced from the bass side to the treble side.
To my ears, the humbucker we used in this guitar works very well paired with the stock P-90 in the neck position. It’s a medium output pickup, so it does have a bit more punch than the P-90 but doesn’t overpower it. Higher output humbuckers can roll off a bit of treble, depending on how they’re made, but this pickup has plenty of brightness for me. Both pickups together have abundant chime and sparkle. I really like this sound!
The proof is in the playing: Marshall tries out the Epiphone Les Paul Special’s new, combined humbucker-and-P-90 sound.
And on top of all that, I think this guitar looks really cool now as well. To me, that’s worth an afternoon’s work.
Learning to use a router is a great introduction to serious guitar modifications. It can be intimidating, but once you learn the basics, it opens up so many possibilities for modifications and repairs. Embrace the router!
Shop DIY tools and Supplies for your next guitar project: https://stewmac.sjv.io/qnPnag
Photo 1
On both guitar and bass, a string tree's primary function is to provide the correct amount of downward pressure on a string so it doesn't rattle and buzz within its nut slot. This downward pressure also ensures that a string will sustain properly when played open. If an open string isn't securely seated in its slot—essentially pinned down the way you'd press a string against a fret—it won't sound as loud or clear as it should.
Whether or not a guitar or bass requires string retainers is determined by how its headstock is constructed. For example, Gibson headstocks tilt back at an angle from the fretboard, and this angle is sufficient to create the necessary downward pressure to keep strings firmly seated in their slots en route to the tuner posts. By contrast, Strats, Teles, and most other guitars with six-in-a-row tuners have flat headstocks that run parallel to the fretboard. On these headstocks, the strings that have to travel the longest distance from the nut to the tuner posts need hardware to create this essential downward pressure.
A string tree's primary function is to provide the correct amount of downward pressure on a string so it doesn't rattle and buzz within its nut slot.
A string tree's primary function is to provide the correct amount of downward pressure on a string so it doesn't rattle and buzz within its nut slot.
Most of us never think twice about string trees until there's a problem. I've already described one—the rattle or sitar-like buzz that results from insufficient downward pressure behind the nut. But if a string tree creates excessive pressure, this can cause premature wear in the affected nut slots and also create tuning issues. And here's another consideration: If you have a whammy bar, certain types of string trees can interfere with the string returning to pitch after you release the bar.
To summarize, string trees can help or hinder your guitar's performance. Let's take a closer look and discuss ways to deal with potential problems.
Design and construction. String trees come in a variety of materials and styles. Most are metal, like the butterfly, disk, and barrel types found on Fender guitars. The metal trees will work, but if you do a lot of bending or use a whammy bar, you'll probably experience tuning problems. Why? Every time the string changes tension against the tree, the metal-to-metal contact creates friction that can cause the string to hang slightly at this point of contact.
Photo 2
To reduce friction—and thus improve tuning stability—you have two options: use a string tree made from a slippery material such as graphite (Photo 2), or install a string tree with built-in rollers that turn with the string as you bend or use the whammy bar (Photo 3).
Photo 3
Both types of retainers accomplish the goal of reducing metal-to-metal friction. I've had great success with Graph Tech string trees, which are made from a synthetic material impregnated with a Teflon-like lubricant, and roller string trees from All Parts.
What's your angle, man? The amount of downward pressure a string tree creates is determined by its location and how high it sits off the headstock. Assuming an identical location, a lower retainer—one that's close to the headstock—will create a steeper angle between it and the nut than a retainer that sits higher off the headstock. Getting the correct angle is critical for avoiding wear (too steep an angle) or sonic artifacts (too shallow an angle).
Photo 4
For a guitar equipped with a single string tree to hold the 1st and 2nd strings, the angle between the retainer and nut should be about the same as the angle between the nut and 6th-string tuner (Photo 4). For guitars that require a second string tree for the 3rd and 4th strings, the angle should approximate that of the 5th string.
Many string trees sit on a separate post or standoff spacer that determines the retainer's height. The attachment screw passes through this washer-like cylinder and goes into the headstock (Photo 5). When the post is a separate piece from the section that actually holds the strings, you can adjust the retainer's height—thereby controlling the string angle—by inserting a shorter or taller spacer.
If the string angle is too shallow and you have a removable metal or plastic spacer, you can increase the angle buy sanding or filing the spacer to reduce its height. Alternatively, you can substitute a shorter spacer: Electronic supply companies sell standoffs for PC boards, and some enterprising guitarists adapt the ball-ends of bass strings for this purpose. Stacking small washers can work too. Whether you need to go up or down, it shouldn't be too hard to adjust the height of your string tree by either modifying it or swapping it out.
Photo 5
Replacing the string tree. If you opt to upgrade to a roller or graphite retainer, it's a very simple project. All you need is a small or medium tip Philips head screwdriver. Lift the strings out from the retainer, remove it, screw the new one in place, and you're done. You might encounter small variations in screw size and threading, but most manufacturers use a consistent size. You can use your original screw if it's in good condition and fits the new retainer.
First-time installation. If you're installing a string tree on a headstock that's never had one—on a replacement neck, for example—string up the guitar and lay the new tree on the corresponding strings, midway between the nut and closest tuner. Confirm the strings are lined up evenly and then, with the screw in place, press down on the tree so the screw makes a small indentation in the headstock. This indentation should lie exactly between the two strings. Use it as a guide for drilling the mounting screw hole.
Start with a pilot hole, using a very small bit. For the screw hole proper, be sure to choose the correct drill bit—it should be slightly smaller than the screw. Measure everything twice, go slowly, and be careful how deep you drill—you don't want to drill completely through the headstock! Before installing the screw, lubricate its threads with a bar of soap or candle wax.
Inserting a delicate screw into a hard maple headstock requires skill, so don't attempt to install a new string tree unless you have the right tools and experience. If you're unsure about your abilities, take the guitar to a qualified repair tech or luthier.
Goodbye string trees. Some manufacturers offer locking tuners with staggered posts. Intended to create the required string angle on a six-in-line headstock without using string trees, staggered posts start out at a normal height for the 6th string and then gradually reduce height, which puts the shortest post furthest from the nut. Depending on the geometry of your headstock, you may be able to eliminate string trees altogether by using these tuners, but the only way to know for sure is to install them and see if you experience any of the sitar sounds or sustain issues that come from having too shallow an angle on your top strings. In most cases, you probably won't need string trees if you have staggered tuners.
Photo 1
Here's a case in point: Recently a client brought me his 1993 Strat (Photo 1) for a setup. His primary concern was that he was having a problem staying in tune, especially when bending one string while holding another. While we were discussing this, he revealed he rarely used the tremolo and kept the bar swung back out of the way when he played. Based on this, I recommended he allow me to lock his tremolo down—or "deck" it against the body. I knew this would resolve many of the tuning issues he was having. He agreed and I proceeded with the relatively simple project described below.
If you're a Strat player who doesn't find much utility in the trem system, you might consider doing this too. This tweak isn't for everyone—many Strat players feel the trem provides much of the guitar's magic. But there are also those who play a Strat because they love its pickups, scale length, weight, and feel, but prefer the stability of having its bridge locked down tight against the body. Some even swear this increases sustain.
Fortunately, it's a reversible mod, so you can try it out and see for yourself. If the tuning advantages outweigh losing whammy capability, great. If you find you miss your trem, you can always return to a floating bridge setup. (I explain that process in the DIY video "How to Float a Strat Trem.")
Evaluating the guitar.
Photo 2
This Strat had spent some time on the road, but it was in good shape. It had a vintage-style, six-screw bridge—not the two-post design of modern Strats. I noticed there were only two springs holding the tremolo to the claw, which explained why the bridge was tilting forward so much (Photo 2).
It's crucial to know the intended tuning and string gauges before you set up a Strat. My client explained he strings up with .010-.046 sets and tunes to standard pitch (unlike some Strat players who tune down a half-step à la Hendrix and Stevie Ray Vaughan).
Getting started.
Photo 3
Getting started. The first step is to remove the cover plate on the back so you can access the claw and trem springs. To provide maximum stability, I added three more springs to the claw (Photo 3) and then used a Phillips screwdriver to move the claw toward the body and tighten the five springs (Photo 4).
Photo 4
The goal is to tighten the springs enough so the tremolo doesn't move when you bend a string. At this point, we're just roughing in the spring tension—we'll come back and fine-tune it in a moment.
Tip: Remember to tune the guitar after every adjustment. If you neglect to do this, you may have to redo your work. This holds true for every step of a setup, including adjusting a truss rod, setting saddle height, and intonating the strings.
Take it to the bridge!
Photo 5
Next, turn the guitar over and make sure the six mounting screws holding the tremolo to the body are all adjusted flush to the bridge plate (Photo 5). Don't tighten them too much, otherwise the tremolo will rock forward on its beveled edge. Lower each screw just enough for the bridge plate to sit flat and flush with the body.
Testing one, two.
Tune up and test the spring tension by bending the strings. Does the trem move at all? If so, tighten the claw a bit closer to the body. Hold a note on one string and bend another against it. You want the held note to stay in tune as you bend the other string. Keep in mind that some guitar necks flex a bit when you bend a string and this will subtly affect the tuning. In this case, we're only paying attention to the tremolo to see if it rocks forward when bending strings.
Be patient: You may need to tighten the springs several times before the trem stays rock solid when you bend. Remember to always tune after every adjustment. Once the trem is secured flush to the body and doesn't tilt forward when you bend strings, it's time to move to the final setup stage.
Adjust the saddles.
Photo 6
Now adjust the action at the bridge saddles. Using an Allen wrench, adjust the two screws to position each saddle to your preferred height (Photo 6). Make sure each saddle stays level and doesn't tilt, and adjust the saddles in a gentle arc that matches the fretboard radius. I explain this operation in "How to Set Up a Fender Stratocaster."
Final setup.
After decking the trem and adjusting the action, the strings may be sitting too close to the pickups and this can negatively affect intonation. So we have to check the pickup height before doing anything else. If you want to brush up on this, read "How to Balance Pickups on Strats and Teles."
After adjusting the pickups, then tackle the intonation. Again, I detail this process in "How to Set Up a Fender Stratocaster."
Beware of Stripped Screw Holes
Occasionally when locking down a Strat trem I've encountered worn out screw holes, either at the spring claw or bridge plate. Stripped-out holes must be doweled and re-drilled, otherwise the screws will continue to strip out more wood and will eventually slip out of the hole. Last year I wrote a column about fixing stripped-out holes for pickguard screws, and the same principles apply here, although in this case the holes are bigger and require a slightly larger dowel. Check out "Got a Loose Screw?" for complete details. Remember, if you don't have the proper tools or knowledge to correctly do this—or any guitar job—play it safe and consult your local guitar tech.
Tip: Always put fresh strings on your guitar before you adjust the intonation.
All right—that's it! You've now locked down your trem and should have a much easier time keeping your guitar in tune.
[Updated 9/24/21]