How many of you out there can explain EXACTLY what a tone knob does and how it’s affecting the sound of your guitar? Some of you may say that it is used to reduce the high frequencies of an electric guitar, but that’s really only half the story. It does explain the change in sound, but let’s take a closer look at what’s really going on.
The tone knob on most electric guitars operates as a low pass filter. A low pass filter operates like it is named. It is a filter for your sound that allows frequencies lower than the set limit of your signal to pass through; IE it filters out all of the frequencies above whatever frequency you choose to set as the threshold. The frequencies are often reduced at a rate of -12dB per octave and sometimes -24dB per octave.
Now that we understand what’s really going on, we can understand the most logical use for the tone knob: to set a high frequency limit to where a guitar sits in a mix. In a rock band type setting, this means avoiding mix conflicts with other high frequency instruments such as cymbals and vocal sibilance (the “ssss” sound). There is a balance to be struck here, however, as the guitar pick attack (which is the most important part of a guitarists’ tone) can get lost if you go too far. What I recommend is to slowly turn the tone knob down until you just start to hear it affects your pick attack, and then back off. Once you find the sweet spot, you generally won’t need to adjust it too much over the course of a performance.
There are other ways of using the tone knob. In the jazz guitar world there are players who have used the tone control to the extreme, most notably Jim Hall. He was known to roll the tone knob down all the way down in order to achieve a dark and warm tone that became his sonic signature. Note that this was a stylistic choice in the context of the right musical setting, however, and that a similar guitar tone would likely not work in a metal band. Speaking of rock bands, Eric Clapton, and his signature “woman tone” was a result of turning his tone knob all the way down while playing with distortion. The reason this works is because the distortion effect creates overtones that allow the guitar to still retain some high frequency information in the tone, thus allowing it to cut through a loud band easier than a clean tone would.