A Different Kind of Tone Control

Posted by Jonathan Beals on 2024 May 21st

The traditional tone knob rolls off high end, like an EQ.  Here's an example of what the results might look like at different positions on the tone pot:

Notice for the first few notches down, it is really only affecting the resonant peak of the pickup.  However, below the 5-6 range it drastically starts to suck the life out of the tone, reducing the midrange substantially, and even producing a low frequency resonance when at its lowest settings.  Some may like that, but I find it tremendously undesirable and unusable.  So, being a mental tinkerer, I'm always brainstorming alternatives.

Getting heavy into pickup winding, you very quickly learn the importance of resistance to ground in a circuit. Resistance to ground has a direct effect on the resonant peak (the tonal character) of the pickup, and less of a general EQ effect like using a traditional tone cap. The less resistance to ground you have, the lower the resonant peak of the pickup. Check out this example of how different pot combinations in the circuit impact the resonant peak of a passive pickup:

Notice the resonant peak dropping consistently as the resistance to ground decreases with lower value pots in the circuit. The key takeaway here compared to a standard tone control is that modifying the resistance to ground does NOT effect anything else in any substantial way. It really only has a significant impact on that resonant peak.

So, here's a great alternative for those like me who are not a fan of traditional tone controls in guitars. Let's say, for a humbucker equipped guitar, you'd use a 500K volume and a 500K tone pot. Instead of using a capacitor to ground in the tone pot, try a 47K resistor. In essence, the tone pot then becomes a "resonant peak amplitude adjuster". At max, it would be normal, like any other guitar. When rolled down to zero, it would reduce the resonant peak by around 12dB. At that, you'd have useful sounds all the way from 0 to 10 on the tone knob, without moving the resonant peak around and causing unwanted low frequency boosts like a traditional tone control.

If you like that really dark tone that comes with rolling your tone knob all the way down, you'll prefer traditional tone controls. But, if you only ever turn your tone knob down to 5-6, and you'd like to have a usable and more gradual sweep all the way from 0 to 10, try this mod and experiment with different resistors (lower resistance for greater reduction in resonant peak; higher resistance for less reduction). You could experiment with different resistor values to get the best results for your particular pickups. Based on my quick calculations, I imagine sticking to the 10K-100K range would make a great starting point.

Happy experimenting!