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Teach Your Neck Pickup to Twang

Have you explored the joys of cutting the lows on a neck pickup? If not, you're missing out. There's a world of 50's hollowbody sounds you can get by thinning the "front" pickup – you'd be surprised how Gretsch 6120-ish you can get a solidbody to sound. Or add some dirt to it and you're in Texas blues territory.

Wouldn't it be great if that "tone" knob on your guitar – the one that just makes total mud out of your sound if you turn it down – actually did something useful?

Here's a fairly simple mod that converts that knob into a bass control. And on a tele or strat, you can put it upstream from the pickup selector, so it works on one pickup and not the other.

Capacitors pass high frequencies and block lows. Your standard "tone" control cuts highs by short-circuiting them to ground. But you can also cut lows just by putting a cap between your pickup and the output. Well... it's almost that simple.

Passive tone controls are RC filters. If you're whipping one up from scratch, you need to know that the 'R' matters. In the case of our high-pass filter, the R is the resistance to ground downstream from the cap. If you do it like the diagram above (as G&L did), the resistance through the volume pot is what's forming a voltage divider with the cap. The smaller that resistance, the more lows the capacitor will cut.

This is why it can be a good idea to create a path to ground from the low end of the bass pot. That'll let the bass pot provide the 'R', and vary it as the pot is turned.

Here are some recommendations for how to implement this in various guitars. In all instances, turning the bass control up makes eveything exactly like an un-modded guitar.

For a tele:

For a strat:

A 4-knob Gibson:

With a Gibson-type pickup switch it's tricky to get the bass cut on the neck pickup without also effecting the "both" position. With the bass control on just the neck PU, the capacitor will not only cut lows but also lower the frequency of the bridge pickup's peak if you turn the control down when both pickups are on. You have to keep the tone knobs cranked to get the classic sparkle of the middle switch position. But that's true with the stock controls, isn't it?

Or you may prefer putting the bass cut downstream from the selector switch, where it will work consistantly on all pickup settings. But if you leave the volume pots upstream of the switch, you should reduce the grounding resistor to 150K.

In some situations, you may have to make do with the ungrounded bass pot. The downsides are that the action of the control gets shoved into the CW end of the rotation, you have to scale the cap according to the volume pot, and you get something that's more of a "slope" control than a bass control.

Here's our Tele version, modeled in P-spice, compared with an ungrounded high-pass done with a .002uF cap. (250K pots.)

The grounding resistor also improves the taper of the control. But it would be better still if the pot was linear rather than audio taper. ∎

Jon Blackstone
Blackstone Appliances

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I like how you did schematics that are almost wiring diagrams.
- Martin G.