All wiring mods are not created equal. Some add a bit of convenience or a subtle new shading, while others are radical departures that open new creative avenues for the adventurous guitarist.
Consider so-called “vintage” or “’50s-style” wiring, in which the tone pot and cap are connected to the middle lug of the volume pot rather than the usual third lug. Given the sheer number of posts the topic has amassed on guitar-geek sites, you’d think it was an earth-shaking option. Yeah, it’s a cool mod that I happen to dig, but really, the sonic benefit is modest: just a bit less loss of brightness when you dial down the volume.
These projects aren’t like that. Each one drastically alters your guitar’s available tones and the ways you access them. They can literally change the way you play.
This article assumes you’re familiar with basic soldering techniques. If not, check out a few YouTube soldering tutorials. I don’t have to remind you to follow all suggested safety guidelines, do I? (Okay—you’re reminded.)
Mod #1: PTB Tone Control
What it is: A variation on the two-band tone circuit that Leo Fender created late in his career for G&L guitars. It employs two tone pots: One cuts highs like a conventional tone control, while the other filters out lows. PTB stands for “passive treble/bass.”
The benefits: This mod is a godsend for players seeking greater control over their distortion sounds, especially with humbuckers. When playing clean, the results are relatively subtle. But when you pour on the gain, even tiny adjustments to your signal’s bass content can add clarity, punch, and welcome variation to your crunch tones.
Just ask any savvy stompbox builder or low-tuned 7-string player: Sometimes the best way to add power to your low tones is to remove a bit of bass. That’s because the lowest frequencies in your signal disproportionately overdrive your amp and effects. Siphoning off just a bit of bass can add clarity and focus. At extreme settings, the filtering can produce sharp, squawking tones akin to those of a ’60s treble booster pedal (not a bad thing). If you’ve ever grappled with high-gain tones that make your amp fart out, here’s your flatulence remedy.
The cost: The original G&L scheme calls for alternate pot values, but the project here uses the 500K pots found in most humbucker guitars, so all you need are wire, solder, and a few capacitors. On a three-knob guitar, you wind up with one master volume control and two master tone controls, but you sacrifice individual volume controls for each pickup.On a four-knob guitar, you still have independent volume controls, but you lose the independent tone controls.
How it sounds: Ex. 1a demonstrates the treble-cut control—nothing surprising here. Ex. 1b features the bass-cut. With a clean tone like this, it’s a bit subtle, though you can hear the difference if you focus on the low notes. But Ex. 1c adds a vintage-style germanium Fuzz Face with the gain and volume maxed. With the guitar’s tone control wide-open, the signal easily overpowers my vintage Fender brownface—your typical Fuzz Face fart. As I gradually trim bass via the guitar, the tone acquires greater punch and clarity. I remain on the neck pickup throughout—the only thing changing is the guitar’s bass pot setting. The extreme-cut settings near the end of the clip may sound harsh in isolation, but they can be perfect in a band context. At the end of the clip I max the bass pot again to underscore how much the tone has changed. It ain’t subtle.
How it works: Diagram 1a depicts Leo’s original schematic:
The signal from your pickups or pickup selector gets routed to two tone pots. The 500k pot and .022 µF capacitor provide a conventional treble-cut control. Meanwhile, the 1M pot and smaller .0022 µF cap filter out lows. (Pay careful attention to the zeros and decimal points in those cap values!) The treble cut creates its effect in the usual way: by diverting signal to ground. But the bass cut doesn’t go to ground at all—the low-filtering cap is inline with your signal. Its output goes to the volume pot (250k in the original). Clever!
Diagram 1b shows my adaptation for three-knob humbucker guitars, using the extant 500k pots:
For visual clarity, I’ve indicated ground connections with a down-facing triangle. As you probably know, all ground wires must be electronically connected to each other. (One convenient method is to solder all pickup ground wires, the output jack ground, the pickup selector ground, and the bridge’s ground wire to the back of the volume pot, and then run a jumper wire to ground the treble control. In conventional wiring, all pots must be grounded, but here, it’s not necessary to ground the bass pot.)
Diagram 1c is a version for four-knob guitars, such as traditional Les Pauls. The only difference: On three-knob guitars, the signal usually goes from the pickups to the pickup selector to the pots. But on four-knob guitars, the volume pots are upstream from the pickup selector to permit independent volume control per pickup.