PU Customization in the Style of Billy Sheehan: Improving Playability with Epoxy Coating

Billy Sheehan, known as a master bassist, cites one of the secrets of his playing style as “playing on top of the pickups (hereafter PU).”

By plucking the strings over the PU, the PU itself effectively acts like a finger ramp, preventing the fingers from sinking in too deeply and enabling a stable touch. As a result, even fast phrases tend to have more consistent note definition, allowing the player to perform without using unnecessary force.

Furthermore, Billy Sheehan achieved an even more ideal height and smoother playing feel by coating the surface of the PU with epoxy resin. When the PU surface is coated with epoxy, steps and unevenness are eliminated, reducing finger catching and significantly easing the stress of fingering.

Coating the PU with resin also has the benefit of reducing noise.
Normally, with PUs that have exposed bobbins, strong string vibration or certain playing techniques can cause the strings to make contact with the bobbin, producing an unwanted “clicking” noise. By covering the surface with epoxy resin, such physical contact is prevented, resulting in a more stable sound.

With that in mind, this time I applied an epoxy resin PU cover coating to the PUs installed on their own PJ bass.
The process itself is simple and does not require any special tools. As a DIY customization, the hurdle is relatively low, and a significant improvement in playability can be expected, so I hope this will serve as a useful reference.

Items to Prepare

• PU covers × 2
• Two-part epoxy adhesive (epoxy resin)

Prepare the PU covers to match the size and shape compatible with your pickups.

⇒ List of Bass Pickup Covers

As for the epoxy resin, I recommend using a type in which the main agent and hardener are integrated, like the one shown in the image.

Because it requires less mixing work and reduces the risk of incorrect proportions, even beginners can use it with confidence. Curing time and transparency vary depending on the product, so choose one that suits your intended use.

Work Procedure

First, thoroughly remove any dirt and oil from the surface of the PU covers.
If dirt remains, the resin will not adhere well and may peel off easily after curing. Lightly wiping with alcohol or a mild detergent is recommended.

Next, to prevent the resin from dripping through the bobbin holes, seal the holes from the back side of the PU cover with masking tape or a similar material. If this step is skipped, the resin can leak inside, making later adjustments very difficult, so be sure to do this carefully.

Once preparation is complete, apply the epoxy resin to the surface of the PU covers.

As a tip for applying the resin, it is recommended to place it in a spiral pattern, drawing a “no” shape on the surface. Because epoxy resin is a viscous liquid, surface tension naturally works to spread it evenly, even if it is applied somewhat roughly. For this reason, it can be considered a relatively easy material for beginners to handle.

Applying the resin slightly thicker makes it easier to adjust the height later. However, applying too much can cause it to drip, so aim for “just before it starts to run” as a guideline.

After application, allow the epoxy resin to fully cure for the amount of time specified in the product instructions.

During this time, it is important not to touch it and to leave it on a level surface. If you rush and move on to the next step, you may end up leaving fingerprints on the surface or it may harden in a warped state.

Once you have confirmed that it has fully cured, install the pickup cover.
Since the PU surface is covered with epoxy resin, lower the bobbins so that they do not protrude above the PU surface. If the structure does not allow for bobbin height adjustment, shave away the resin from the bobbin hole area on the back of the PU cover so that the bobbins fit properly.

After the PU cover is mounted onto the PU, reinstall it on the body of the bass.

Because the thickness of the epoxy resin increases the distance between the bobbins and the strings, it is recommended to set the overall PU height slightly higher. While checking the output level and attack, find the position that suits your preference.

If the resin interferes with the strings, use sandpaper or similar tools to gradually shave down the resin and adjust the height and shape. Epoxy is easy to sand, making fine adjustments relatively simple.

Impressions After Trying It

This was my first time doing this process, but it turned out to be much easier than I had imagined.
Thanks to the surface tension of the epoxy resin, even the corners naturally cured with rounded edges, resulting in a very clean finish.

The PU I used in this process was a DiMarzio Model P, which is known to have been actually used by Billy Sheehan.

DiMarzio / DP122 BLACK Model P

This PU is extremely powerful, but by increasing the distance between the bobbins and the strings through epoxy coating, the output was slightly reduced, resulting in a more controllable sound.

In addition to improved playability, a major advantage is that the touch becomes more stable, making it possible to play fast phrases without using unnecessary force. There is also a sense of reassurance in knowing that the original condition can be restored simply by replacing the PU cover.

I highly recommend this customization for those who want to try a finger ramp but do not want to change the appearance of their instrument.
If this has caught your eye, why not give it a try?

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