The Challenge
We all know the problem, right? Single-coils have a clear, bell-like tone with a lot of highs, but they are very prone to pick up hum and noise, and this can be a nightmare in the studio or onstage. If you want to keep your original single-coil pickups—and not swap them out for humbuckers—you can mod your guitar in three steps to banish the noise. But first, you'll want to complete two preliminary stages.
Shield the pickguard and guitar cavity. The web is full of great DIY instructions for doing this, so I won't rehash that info here. But I will add one thing: In my experience, copper foil is superior to aluminum foil or tape, as well as all forms of shielding paint. And remember, it's crucial that all shielding materials are connected to ground. Otherwise they're mostly useless.
Photo 1 — Courtesy of singlecoil.com
Replace standard wire with shielded wire. This is a simple swap: Substitute shielded wire for all the standard wire in your guitar. Keep in mind that the braided shield of all the new wire must be connected to ground. (You can also replace the two standard wires on your single-coil pickups with shielded wire, and in a moment, I'll explain when and how to do this.)
Okay, now we're ready to shield the pickups. It's not a complicated task and you don't need much in the way of materials, but you must do it correctly. If you don't, all the marvelous high end of a single-coil goes down the toilet. Every week I get at least one emergency call from someone who tried to shield a Strat's pickups and wound up with a dull and lifeless-sounding guitar. It's a hassle to undo the mistake, so let's get it right from the get-go. Ready?
Every week I get at least one emergency call from someone who tried to shield a Strat's pickups and wound up with a dull and lifeless-sounding guitar.
We'll start with the materials. As shown in Photo 1, you'll need conductive, self-adhesive copper tape, self-adhesive pickup-coil tape, a piece of solid-core wire, and some alcohol or naphtha. These items don't cost much, and you can buy the copper tape and pickup-coil tape on eBay or from luthier and pickup-building suppliers. For this project, our guinea pig is a standard Stratocaster pickup. For this type of pickup, the ideal width for the tape is 3/4" (approximately 19.1 mm).
Step 1: Protect the pickup's windings.
This is where the pickup-coil tape comes in. When you look at a standard Strat pickup without its plastic cover, you'll see the windings are unprotected. If you left them this way, you'd be affixing the copper tape directly to the windings. But even the back of the copper tape is conductive, so if there's any damage to the thin coating on the windings, the resulting contact will short out the pickup. Older pickups are particularly vulnerable to this, so to avoid the problem, we'll carefully wrap the pickup-coil tape around the windings to completely cover them.
Photo 2 — Courtesy of singlecoil.com
In most cases, you'll need two wraps to accomplish this. Don't worry if one wrap overlaps the other, and be particularly careful to cover everything at the base of the pickup—an area that's often overlooked. You don't want any of the copper windings peeking through, so to be on the safe side, I like to partially cover the base with tape. Using a pair of small scissors, I'll cut a thin strip of tape, then fold it down and press it onto the base, all around the windings. By the way, if you ever need to remove this special pickup-coil tape, you can easily do this without damaging the pickup. Photo 2 shows what the pickup looks like after it has been wrapped.
Step 2: Surround the pickup with copper tape.
Photo 3 — Courtesy of singlecoil.com
The copper tape's 3/4" width is perfect for surrounding the pickup because you only need one wrap to accomplish this (Photo 3). But it's essential that the two ends of the tape don't touch each other. This means no overlap and, of course, no solder connecting the two ends of the copper tape.
Photo 4 — Courtesy of singlecoil.com
It's crucial to have a little gap between the two ends of the tape to keep all the high end alive (Photo 4). Not having the gap is exactly why so many shielded pickups lose all their highs, and in a moment, I'll explain the reason.
Note: Be sure the gap isn't right where the pickup's two wires are attached, because in the next step, we'll need that space to connect the copper wrap to ground. Otherwise, it's not important where the gap is or how wide it is. I like to place the gap on the opposite side of the pickup from where its two wires are attached.
Why is this little gap so important? If you close the copper-tape wrap so the two ends make contact, the loss of all high end is unavoidable. You'll often read this is because the capacitance of the pickup's winding increases against ground. While this is electrically true, it is not the reason for the loss of high end. The real reason for the high-end loss are eddy currents in the metal film, which act like a shading coil in a transformer. The gap breaks the eddy currents and the loss of high end is minimal—and in most cases, not even audible.
Step 3: Connect the copper tape to the pickup's ground.
In this last step, we engage the shielding function. This is also the point to decide if you want to swap the two standard pickup wires for a shielded cable. If you elect to do this, simply connect the braided part to where the black wire was originally connected, and the hot of the shielded wire to the white wire's former location.
Photo 5 — Courtesy of singlecoil.com
Take a piece of solid core wire and solder it to the spot where the black pickup wire connects to the base. Next, use some alcohol or naphtha to clean the area on the copper tape where you plan to solder the solid wire. This cleaning makes the soldering process much easier because the solder sticks perfectly to the copper. After the area dries, solder the wire to the copper tape (Photo 5).
Photo 6 — Courtesy of singlecoil.com
Note: Be sure the wire is long enough that you can bend it toward the copper foil (Photo 6) to allow the plastic cover to fit over the pickup.
Congratulations—you're done! In a future installment of Mod Garage, we'll apply everything we worked out today to shielding plastic pickup covers. Again, we'll do it the right way so you don't lose any high end.
But next time, we'll continue our study of pickup parameters by bringing phase and polarity together. Until then ... keep on shielding!
[Updated 8/16/21]
Photo 1
Not long ago, a customer brought me a Vibrolux combo he'd recently acquired. He wanted to make it one of his regular gigging amps, so he asked me to make sure it was roadworthy. He wanted new caps, tubes, and whatever else was needed. He also wanted to remove and safely stash the original speakers while they were still in working condition. His idea was to thrash a new set of speakers on gigs and not be concerned about reliability or destroying a piece of Fender history.
Replacing speakers is actually a great upgrade for any amp of this era because speakers grow tired over the years, and a fresh set can yield a far greater improvement than most players would believe. In fact, when I install new speakers in an old amp, the owner typically experiences a wow moment. (If you have an older amp, try it—you might have that reaction too.)
Before I dive into repairing or modding an amp, I always ask how the owner expects to use it. For example: Do you like to play dirty, or are you after a big, clean tone with maximum headroom? This feedback gives me an idea of what type of tubes to install and how to tailor the circuit to the player.
It turned out this customer performs a lot of music inspired by Jonny Lang and Kenny Wayne Shepherd. Great—this gave me a reference and prompted me to offer some suggestions. We all know these players were very influenced by the late, great SRV.
Before I dive into repairing or modding an amp, I always ask how the owner expects to use it.
In my brief time working with Stevie before his death, I saw that his massive backline included two Fender Super Reverb combos, each loaded with four Electro-Voice 10s—his favorite speakers for these amps. How he managed to blow speakers with such massive power handling capability with a 40-watt Super is beyond me, but his tech at the time, the legendary René Martinez, always had spares on hand. Anyway, let's see what this knowledge can do for my customer.
First, a Vibrolux Reverb is a bit like a mini Super Reverb. With a dual-6L6 output stage, the amps offer about the same power, but the Vibrolux has two 10s instead of the Super's quad set. But they're voiced differently: While most blackface and silverface Fenders use the same value capacitors in the tone stack—a 250 pF, a 0.1 µF, and a 0.047 µF—the Super Reverb has a 0.022 µF cap in place of the 0.047 µF.
My suggestion was to modify the tone stack in the Vibrolux's first channel. This way, one channel would remain stock, the other would be a bit more like a Super, and he could use an A/B switch to access either channel as desired.
Regarding speakers: Unless you can afford a roadie, I wouldn't advise loading a Super or even a Vibrolux Reverb with EV 10s. These bad boys are heavy! Instead, I suggested swapping in a lighter set of contemporary 10s that sound similar to the EVs. The owner agreed, so let's look at what we did.
Photo 1 shows how I've installed not one but two new caps in the amp's first channel. I like replacing both the .047 and 0.1 µF caps with .022 µF caps. It makes the channel a bit beefier, and that's nice for a guitar with single-coil pickups. It also leans more towards a Marshall tone stack at this point ... but not quite. Of course, Stevie was also a Marshall guy (got to love those 200-watt Majors), so if you really want to go all the way, you can replace the 250 pF treble cap with a 470 pF, but that's not something I wanted from this particular amp.
Photo 2
Now, at this point I'm sure some of you are saying, "Yeah, cool, but there's no reverb on the first channel." Well my friends, I have a bonus for you. Look at Photo 2 and notice the blue wire. That's the audio signal wire from channel 1, which was originally connected to the circled eyelet on the right. Simply remove the wire from this connection at the input of the phase inverter and connect it to the input of the reverb drive circuit, as illustrated on the left of the photo. This routes the channel 1 signal to the reverb and tremolo circuits.
Photo 3
Cool—one more bonus! Finally, for just a little extra push, I like to move the unused 220k resistor and place it in parallel with the other 220k resistor at the input to the phase inverter (see photo).
After making these mods, I installed a new pair of 10" speakers (Photo 3), and the amp was ready for the road.
[Updated 9/1/21]