Pickup Lines
In the second part of our focus on pickup controls we talk tone with Bare Knuckle Pickups’ tech support whizz Tim Bartle
In last issue’s Pickup Lines, we spoke with Bare Knuckle Pickups’ Tim Bartle to find out how different types of potentiometer can help bring out the best in our pickups and performance, and this time around we pick up the thread with Tim about guitar tone control. Much like guitar volume control, it is often underexplored by players, although a little knowledge and experimentation can yield some very pleasing results.
“The two main types of capacitor used in guitars are ceramic disk capacitors and paper-in-oil capacitors,” says Tim. “Although they work in a similar way and may have the same values, the curve of impedance as you sweep through the frequencies is slightly different. It’s a part of that whole interacting system along with your pickups, pots, cables, the front-end of your guitar amp and any pedals you might be plugged into. Everything works
“When you change the value of a capacitor, it changes the frequencies that can pass through it”
in unison. It’s a very subtle difference and it’s going to vary with different setups, but we find paper-in-oil caps give you a clearer tone and a little more detail.”
A regular guitar tone control is a simple filter control with two main components, a resistor (the tone pot) and a capacitor.
“The capacitor acts as a high-pass filter to ground, effectively filtering out and removing those higher frequencies from the output signal,” continues Tim. “Altering the resistor – either by adjusting the knob or using a different value pot – or by changing the capacitor for a different value, changes the cutoff frequency of the filter, above which point the frequencies pass to ground. As you move the tone knob away from 10, you’re gradually shifting that point downwards from the higher frequencies into the mids and, therefore, an increasingly darker tone is produced.
“Capacitors are a component that can be charged and discharged of electrical voltage. It’s time-based and that rise time/ charge and fall time/discharge determines which frequencies will be able to pass through it and which ones won’t – voltage goes up and down quicker with higher frequencies than lower frequencies. The different values of a capacitor reflect the differing amounts of time that takes, so when you change the value of a capacitor, it’s going to change the frequencies that are allowed to pass through it. Generally, you’ll get a darker tone if you increase the capacitance because it will let more upper frequencies through, which are then filtered off. [See The Mod Squad ‘Control Your Tone’ feature on p122 for more information on cap values.]
“If you want more range on your tone control, you can change to a higher value capacitor, which will give you a darker sound when you roll the knob all the way down. When you roll the tone all the way down, that’s your max cut-off, and changing the cap changes your max cut-off.
If you have a high capacitor value, you’re going to have a much broader sweep of tone from 10 down to 0 than if you went for a lower capacitor value.
“Different types of pots – linear and logarithmic – don’t change the limits (at 10 and 0) but they do change how the tone sweep feels from one end to the other. It’s down to personal preference, but if you use the tone control in a more dynamic way, then a logarithmic pot gives you a little more quick-fire adjustability; you can make small adjustments that make a big difference to your tone. If you just want to dial in a tone and leave it, then a linear pot will probably give you a bit more control as it provides a smoother sweep from 10 down to 0.
“It’s all down to what you want to achieve,” Tim concludes. “Okay, a guitar comes out of a factory in a certain way, but it’s about finding the voice in your guitar that you want to find. Developing a critical ear can really help you learn what you like and what you don’t like. It’s all about working with it, getting it close and then tweaking it to get it exactly right. Then you get your rewards.” [RB] www.bareknucklepickups.co.uk
“Developing a critical ear can really help you learn what you like and what you don’t like”