Capacitors are used in guitars and pedals to modify the tone of the guitar. They come in handy when it comes to creating low pass and high pass filters; or in simple terms, they are the magic component that make your tone sound more punchy and transparent or more muffled. So if you’re looking to modify your guitar or pedal to change the tone, this article will provide all the necessary information for you to experiment with capacitors.
What is a capacitor?
Generally speaking a capacitor is a like a baby battery and it’s used for many purposes. This component has the capacity of storing electrical charges (thus the name “Capacitor” from “capacity/capacitance”) and releasing it. For example when you turn off a device in your home and you notice that it doesn’t turn off immediately after hitting the switch it’s probably because a capacitor is in the circuit and it released the electrical charge it had stored.
Capacitance (C) is measured in a unit called Farads (F) and this usually determines the size of the capacitor. The unit “F” or Farads is named after the scientist Michael Faraday who contributed not only to the scientific field but also to Rock & Roll in an indirect way.
The values of capacitance are given in pico(p), nano (n), and micro (μ) Farads
| Unit | Symbol | Value |
|---|---|---|
| Farads | F | 1 F = 1 F |
| Microfarads | µF | 1 µF = 1,000 nF |
| Nanofarads | nF | 1 nF = 1,000 pF |
| Picofarads | pF | 1 pF = 0.001 nF = 0.000001 µF = 0.000000001 F |
What is a capacitor used for in guitars?
Capacitor are used to change the tone of your guitar. You can find capacitors in pedals or attached to the tone knob(s) within your guitar. Why is that? Well technically the “Tone Knob” is a combination of a capacitor and a potentiometer.
The potentiometer is an adjustable resistor and when you add a capacitor in the same circuit you can control the cutoff frequency and get a high pass or low pass filter. Time to define some terms I guess.
Cutoff frequency
In a low-pass filter, the cutoff frequency is the frequency (Hz) where the filter starts, allowing lower frequencies to pass through and gradually reducing the strength of higher frequencies. It lets the bass and lower tone through while blocking the higher treble tone.
In a high-pass filter, it’s the opposite. The cutoff frequency is where the filter begins, allowing higher frequencies to pass while blocking lower frequencies. So, it’s like a filter that lets through the treble and high-pitched tone while reducing the strength of the bass and low tone.
The cutoff frequency formula is derived from the capacitive reactance formula where Xc= 1/2πFC. Capacitive reactance (Denoted Xc) is the name given to the Capacitor’s resistance, which changes as a function of the frequency. This means when the Frequency increases, the capacitive reactance(Xc) resistance decreases and vice versa.
Here’s the formula to calculate the cutoff frequency or know which resistor or capacitor to use accordingly: F= 1/2πRC
- F: Cutoff frequency
- R: Resistance
- C: Capacitor
- π: In math pronounced pi, equal to approximately 3.14
This formula is important because it means that by changing the resistance (R) or the Capacitance (C) we can change the cutoff frequency! And what is the best of doing that? Use a potentiometer to change resistance or change the capacitor! This gives us the ability to change resistance with a knob and ultimately change the cutoff frequency or the tone of the guitar.
Changing the cutoff frequency with a potentiometer
Here’s an example of a guitar tone pot’s circuit where you can see a capacitor and a potentiometer. By turning the tone knob you simply shift the cutoff frequency, keeping the formula F= 1/2πRC in mind:
- By turning the potentiometer clockwise between pins 1|2 & 3:
- Resistance R between both pins decreases ↓
- Cutoff frequency F increases ↑.
- High frequencies will be allowed to pass (high pass filter)
- Your guitar tone will have more treble and sound more transparent
- By turning the potentiometer counterclockwise between pins 1|2 & 3:
-
- Resistance R between both pins increases ↑
- The Cutoff frequency F decreases ↓.
- Low frequencies will be allowed to pass(Low pass filter)
- Your guitar tone will have more bass and sound more muffled
-
Changing the cutoff frequency with a capacitor
If you’re not satisfied with the tone changes achieved through the potentiometer, you can change the capacitor your are using to achieve the cutoff frequency. Remember the formula F= 1/2πRC.
Given that resistance R is constant:
- A higher capacitance value means a lower cutoff frequency and a more muffled or bassy sound
- A lower capacitance value means a higher cutoff frequency and more transparent sound with more treble
Common types of capacitors
Capacitors come in different shapes and sizes! You can find polarized and non-polarized capacitors in guitar and bass pedals.
Non-polarized capacitors: it doesn’t matter in which orientation they are wired in the circuit.
Polarized capacitors: it’s the opposite. The polarity of this type of capacitor is marked with a negative sign and a shorter leg for the side that should be connected to the ground
Common types of Capacitors include Film capacitors, Electrolyte and Ceramic. Here are some of the most common capacitance values:
| Capacitance | Value |
|---|---|
| Picofarad (pF) | 10 | 15 | 22 | 30 | 33 | 47 | 68 | 75 | 82 | 100 | 150 | 220 | 330 | 470 | 680 |
| Nanofarad (nF) | 1 | 1.5 | 2.2 | 3.3 | 4.7 | 6.8 | 10 | 15 | 22 | 47 | 68 | 100 |
| Microfarad (µF) | 0.22 | 0.47 | 1 | 10 | 2.2 | 4.7 | 22 | 33 | 47 | 220 | 470 |
Capacitor Materials for Guitar Pedals and Guitars:
Capacitors come in various materials, and the choice matters in your quest for the perfect tone. Consider the following:
Film Capacitors: Known for precision in audio applications, film capacitors can enhance the subtleties of your guitar’s tone. These are good for refining your guitar’s sound, helping you hear subtle nuances in your playing.
Electrolytic Capacitors: Commonly used in power supply circuits, electrolytic capacitors play a vital role in maintaining stability in your pedalboard or guitar’s power delivery. Think of these as the power regulators in your setup. They make sure everything runs smoothly, like the heart of your pedalboard or guitar’s power system.
Ceramic Capacitors: These versatile components are found in various electronics, including guitars and pedals. Their characteristics can influence your sound, making them an intriguing choice for experimentation. These are like the all-rounders. They’re used in many electronics, including your guitar and pedals, and can influence your sound in various ways.
Additional notes
Capacitor Tolerances for Tone Perfection:
Capacitors have tolerances that indicate how closely their actual capacitance matches the specified value. When fine-tuning your tone, pay attention to tolerance values, as they can impact the precision of your tone modifications. Capacitors'”tolerances,” basically tell you how close the capacitor’s actual value is to what’s written on it. For your tone-tweaking adventures, just know that smaller tolerance numbers are better for fine-tuning your sound.
Keeping Your Sound Clean:
Some capacitors can be a bit leaky over time. To avoid any hiccups, especially when you’re going for that perfect sound, opt for capacitors that don’t have this issue.
Getting Your Wiring Right:
When you’re working on your guitar or pedalboard, making sure you connect capacitors properly is essential. This can be as simple as getting the right wires in the right place to get the sound you want.
Staying Safe and Protecting Your Gear:
Your safety and your gear’s health matter. Make sure your setup is secure, properly grounded, and insulated to prevent any electrical surprises, and you can focus on making music worry-free.
In conclusion, capacitors are like the seasoning in your musical recipe. Understanding how they work, even if you’re not an electronics whiz, can help you create your unique sound. Stay safe, have fun experimenting, and remember that your musical journey is all about finding your own groove.
