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Harley Benton GuitarBass - Electronics Mods

By Sammy of Stone Marmot

Nov. 4, 2024

I recently bought a new Harley Benton GuitarBass (HBGB), which cost less than $300 including sales tax and shipping. I've been very happy with it and use it a lot. But it is not ideal. Hence, I made the following modifications to approach a more ideal instrument.

The HBGB has single coil pickups, which tend to be more prone to noise pickup than humbuckers. My HBGB is no worse in this regard than any other instrument I've owned with single coil pickups. But I ended up shielding the cavities of these other instruments to reduce this noise pickup. So I did the same with my HBGB.

Figure 1 shows the electronics cavities of my HBGB. The cavities are painted with regular black paint which I verified is not conductive. Notice the posts for the harmonica bridge are installed. The black wire shown is attached to one of the threaded inserts for the bridge so the bridge, strings, and all other metal touching these items is grounded.

Figure 1 - Electronics cavities of the HBGB as first received

Figure 1 - Electronics cavities of the HBGB as first received

Figure 2 shows the back side of the pick guard. The only shielded wires present are one between the volume and tone controls and one between the volume control and the output jack. The rest of the interconnect is done with regular insulated stranded wires.

Figure 2 - Back of pickguard as received

Figure 2 - Back of pickguard as received

I replaced all the regular stranded wire with shielded wire. This alone will help reduce noise pickup.

I lined all the cavities with self-adhesive copper foil tape, as shown in Figure 3. I also put this copper tape on the pick guard under the controls and over the top of where the cavities would be, as also shown in Figure 3. You could use conductive paint to do this. But conductive paint is more expensive, dries out within a couple years of originally opening the container, and is harder to reliably attach a ground wire to. Many also feel copper tape is more effective as a shield. Just make sure you have continuity between each of the strips of copper tape.

Figure 3 - Cavities and pickguard after shielding with copper tape

Figure 3 - Cavities and pickguard after shielding with copper tape

I also wrapped one layer copper tape around the pickups under the pickup covers. I left a gap between the ends of the tape so that the ends aren't touching. If the ends touch, you could have a continuous eddy current flow around the pickup which could reduce the high frequency response of the pickup. A wire from each of these copper tape shields under the pickup covers is tied to the shield of the shielded wire coming from each pickup. A more detailed description of this is discussed at https://www.premierguitar.com/diy/mod-garage/shielding-single-coil-pickups.

All this copper tape has to be tied to ground to be effective. I soldered a wire to the copper tape in the cavity and then to the ground side of the output jack. The wire coming from the bridge post is also soldered to the ground side of the output jack. These black wires are shown in Figure 3. The copper tape on the backside of the pickguard is grounded via contact with the output jack, the two controls, and contact with the copper tape in the guitar cavities that wraps around to the top of the guitar body.

The Fender Bass VI has four switches on it. There is one for each of the three pickups to turn that pickup on and off. The fourth switch, which is often referred to as the "choke" or "strangle" switch, significantly reduces the bass response of all the pickups, making them sound much brighter, which can be useful when playing solos. Rather than adding a switch to perform this strangle function, I replaced the tone control itself with a Fender TBX style tone control. Then I wired this TBX control as discussed in bandmate Sid's article "Versatile Telecaster Controls." This allows the tone control to act like a normal passive tone control the lower half of its range, cutting highs and make the instrument sound bassier. But the upper half of the range it cuts the lows, making the instrument sound brighter. At control midpoint, which has a detent, the bass sounds normal. Again, this is discussed in detail in Sid's article. Figure 4 shows the schematic of the volume and tone control section of the HBGB electronics with the TBX tone control.

Figure 4 - Schematic of HBGB controls with TBX tone control

Figure 4 - Schematic of HBGB controls with TBX tone control

Figure 5 shows the finished assembled body of my HBGB. The entire completed HBGB shown in Figure 6. I replaced the volume and tone control knobs with some spare chrome Telecaster knobs I had in my parts stock, which better match the bridge, tailpiece, and old tailpiece posts. After these pictures were taken, I replaced the black knob on the pickup selector switch with a white knob to better match the pickups and the binding on the neck. I'm happy with the final result. The bass now meets my needs and I think it also looks better.

Figure 5 - Finished body of my Harley Benton GuitarBass

Figure 5 - Finished body of my Harley Benton GuitarBass


Figure 6 - My Harley Benton GuitarBass after all my mods

Figure 6 - My Harley Benton GuitarBass after all my mods


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