Installing A Fernandes FSK-101 Sustainer

It’s exhilarating to push a guitar into feedback and hear notes howl like a wounded banshee, but this usually requires cranking a burly amp in a big room—something most of us don’t get to do very often. For years, Fernandes has offered a viable alternative to the cranked-amp scenario. Their onboard Sustainer magnetically drives a guitar’s strings, making it easy to generate infinite sustain and controlled feedback at any volume. One catch: Until recently, this electronic device was available only in a Fernandes 6-string (see the Dec. ’05 GP for a review of the Sustainer-equipped Dragonfly Elite). When the company began selling Sustainer kits for retrofitting other manufacturers’ guitars, it seemed like a great idea. But how hard is it to equip a guitar with a Sustainer? And what’s the total cost?
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To answer these questions, I decided to hot-rod a guitar with Fernandes’ new FSK-101 ($199 retail/$150 street)—a Sustainer kit designed for instruments with a neck-position humbucker. Fernandes makes it clear that installing a Sustainer requires professional woodworking and wiring skills, so I enlisted the help of Lauren Ellis and Tony Nagy—expert guitar techs who each operate repair shops in Nashville.

The FSK-101 consists of a neck humbucker pickup/magnetic string driver, a circuit board with two mini-toggle switches (Sustainer on/off and standard/harmonic mode), a flip-top battery compartment, a stereo jack (inserting a standard ¼" cable turns on the preamp, which runs whether or not the Sustainer circuit is engaged), all necessary wires, and an accurate—but sometimes vague—photocopied set of installation instructions. Here’s something Fernandes doesn’t emphasize in their Sustainer materials: The two switches are directly mounted on the board, perpendicular to its surface. Because they both protrude at the same fixed height through the top of the guitar, you must either mount the Sustainer in a flat-top axe (such as a Telecaster or Les Paul Junior), or find a carved-top instrument with a level area that’s wide enough to accommodate both switches.

Knowing I had my heart set on supercharging a Telecaster, Ellis told me she’d seen Mexican-made Fenders pre-routed for a neck humbucker, even when the guitars were equipped with a standard neck single-coil. After prowling local music stores, and peering beneath pickguards, we found a used 2001 Tele that felt good, looked sharp, and was indeed factory routed for a humbucker (Fig. 1). Sold!

To hold the Sustainer driver, I bought a white pearloid Tele ’bucker pickguard on eBay from Fernandes specifies that the bridge pickup—not part of the Sustainer package—must also be a humbucker. Based on several recommendations, I chose a Duncan STK-T3b Vintage Stack (a drop-in humbucker replacement for the stock Tele bridge single-coil).

It’s crucial to carefully plan circuitry and battery placement before you start hacking. We decided to position the two switches behind the bridge to keep them away from strumming or picking (Fig. 2). Ellis then measured the distance between the switches, and marked where they’d emerge on the guitar (Fig. 3). To keep the switch holes perfectly vertical, she used a drill press, entering from the top and boring through the body into a block of scrap wood (Fig. 4).

Routing the rear compartments to house the electronics and battery is not for the faint-hearted. The kit doesn’t include routing templates, so first Nagy defined the circuit board cavity’s perimeter using blue, safe-release masking tape, and then outlined the cavity edges with a Dremel tool. Guided by this outline, he used a router to carve a deep, rectangular hole in the back of the body (Fig. 5). As Nagy approached the top of the guitar from inside, he stopped to measure the circuit board to confirm the cavity depth, which needs to be routed to approximately 1/8" from the guitar top (Fig. 6). There’s no room for error at this stage, and the manual doesn’t provide these dimensions. Next, Ellis and Nagy measured the battery compartment (Fig. 7), and Nagy tackled the routing. It takes a pro to route such clean holes (Fig. 8).

Before mounting the circuitry (Fig. 9), Nagy drilled lateral wire conduits between the two routed compartments and the Tele’s control cavity. All connections to the circuit board are made with clips, but serious soldering skills are required to attach the tiny circuit board wires to the pickup selector switch (Fig. 10) and connect the battery connector, volume and tone pots, and ground wire to the output jack. At this stage, Nagy replaced the stock 250k-ohm volume pot with a 500k version—the standard value for humbucker pickups. At my request, he also rotated the Tele control plate to put the volume knob closer to my picking hand. No cover for the electronics cavity is included with FSK-101, so Nagy fabricated one from a piece of plastic and mounted it on the Tele’s back (Fig. 11). This cover is easily removed to access the Sustainer’s trimpots for adjusting output, attack, gain, and pickup balance. Once we’d tested the electronics, the hard work was done.

Back in my workshop, I replaced the heavy bridge and saddles found on modern Telecasters with a lighter—and much twangier—Fender stamped-steel bridge and saddle assembly. To surgically tame the high-end fizz that sometimes rides above notes generated with a magnetic string-driving system, I swapped the stock Tele tone pot for a 14-capacitor Stellartone ToneStyler treble-cut control. To complete the “pimp my ride” vibe, I installed black aluminum knobs and slapped on a Grateful Dead sticker (Fig. 12).

Capable of droning ambient textures, fat pedal-steel licks, wicked organ sounds with a Leslie simulator, and ballsy blues bends laced with whistling octave harmonics, this Sustainer-equipped Tele sounds great—especially set up with heavy strings (gauged .056, .044, .032, .019, .016, .012), and tuned down a whole-step to “D standard” (D, G, C, F, A, D). Drop-tuned heavy strings put more steel in the driver’s magnetic field—thus generating more sustain—yet don’t feel unbearably stiff. With the Sustainer off, the Fernandes humbucker is functional, if not sonically exciting. (Incidentally, the Duncan STK-T3b delivers badass honky tonk tones, with or without the Sustainer.) There’s one potential drawback to this mod: Once you install the Sustainer, you have an electronic guitar. If the battery dies, there’s no output, even with the circuitry switched off.

The cost? To have the FSK-101 professionally installed, budget for three to four hours of shop time (at, say, $50 an hour), plus the cost of any additional parts, such as a pickguard, bridge humbucker, volume pot, etc. Including the FSK-101, this can total $400 or more. Still, assuming you already own the guitar, that’s less than buying a Fernandes Sustainer 6-string. Best of all, you get major bragging rights for playing a customized instrument.

Fernandes Guitars, (800) 318-8599; To inquire about getting a Sustainer installed by Nagy Guitar Restoration, visit