The world of guitar effects pedals is vast and diverse, offering a seemingly infinite array of tonal possibilities for musicians to explore. From creating atmospheric soundscapes to adding that extra punch to your riffs, these compact devices can drastically change your sound with just a stomp of your foot.
In this article, we’ll delve into the essential types of guitar pedals, providing an overview of their characteristics and uses. We’ll start by categorizing the various types of effects pedals, and then we’ll analyze the function of pedals in each category. From distortion and overdrive to modulation and time-based effects, we’ll help you navigate the colorful landscape of stompboxes and unlock new creative avenues for your playing.
- Understanding the Main Guitar Effects Pedal Categories
- Gain Changers
- How Distortion Pedals Work
- How Overdrive Pedals Work
- How Dynamics Pedals Work
- How Guitar Equalizer Pedals Work
- How Modulation Pedals Work
- How Time-Based Effects Work
- Multi-Effects Pedals
Guitar effects pedals fall into the following categories:
- Clean boost
- Treble boost (also fits into Equalizers)
- Noise gate
- Noise suppressor
- Graphic EQ
- Semi-parametric EQ
- Treble boost (also fits into Gain category)
- Pitch shift
- Octave divider
- Rotary simulator
- Ring modulators
- Wah pedal
- Talk box
Understanding the Main Guitar Effects Pedal Categories
As recording engineer and educator Tom Lubin (Electric Ladyland Studios) once said, “There are two types of distortion: the kind you like, and the kind you don’t.” We’re going to talk about the kind we like.
Originally, distortion came from overdriving preamps, power amps, output transformers, and speakers. Overdrive is boosting gain until a waveform clips. Clipping is when the peaks and valleys of a signal exceed the available headroom of a system and the tops of the waveform flatten, hence the term, “clipping,” since the waveform looks like the top has been cut off or clipped (like a military buzz cut). Distortion also came from other physical sources such as torn speakers and loose tubes.
You may have noticed in the list above that overdrive pedals appear in two main categories, Gain and Distortion. The reason for this is that overdrive and distortion pedals create distortion with transistors emulating the sound of overdriven tube amps, rather than overdriving the amp itself. As a result, distortion and fuzz pedals don’t produce significant changes in level. If fact, rather than gain-changing pedals, they could be considered modulation pedals (more on that later), since they alter signal without boosting gain.
How Distortion Pedals Work
We mentioned above about a waveform exceeding the headroom of a device and resultant clipping. If you send a guitar signal into a distortion pedal, there’s really no possibility of overdriving the pedal, since the guitar output is a low-level signal.
So, how does a distortion pedal create the effect of clipping?
Simply by splitting and then combining two signals that are in phase. The second signal is a low-amplitude, high frequency signal that’s combined with the unaltered signal. As the signals are combined, the amplitude of the combined waveform exceeds the headroom of the pedal, which flattens the peaks and changing the shape of the waveform to resemble various types of tube amplifier distortion.
If you look at the definition of modulation, which is one signal altering another, you can see why we said that distortion pedals could be categorized under modulation. That said, you might place a distortion pedal almost anywhere in the signal chain, but experience tells us that they sound best when acting on the full-range signal of the guitar. However, if you were in a rebel-without-a-cause kind of mood, you could place distortion pedal after a chorus pedal, for example, and see if you like the sound of distorted chorus.
How Overdrive Pedals Work
An overdrive pedal is designed to duplicate the effects of overdriving a guitar amp by increasing input gain. In the case of overdrive, distortion occurs when playing harder, while softer playing keeps the signal clean. An overdrive pedal works the same way a distortion pedal does, but with softer clipping, which in turn maintains the original timbre of the instrument. This is why you want to put overdrive first in your signal chain.
Fuzz pedals, like the ones made popular by Jimi Hendrix, use an adjustable frequency multiplier to add extra harmonic overtones. This creates a rounder, warmer distortion.
Fuzz pedals can also be considered modulation effects, but since they, like overdrive and distortion pedals, duplicate the sound of overdriven circuits, they should be placed in a position analogous to gain devices in a console channel strip or guitar amp. In other words, up front.
How Dynamics Pedals Work
Guitar effects pedals in this category include compressors, noise gates, noise suppressers (expanders), and sustainers. These pedals affect the envelope of a sound.
A compressor is a gain-reduction device that outputs a lower voltage than it takes in. For example, a compressor set with a 2:1 ratio outputs one volt for every two volts coming in.
The threshold control determines the signal level that the compressor acts on. Ratio sets input vs. output voltage; release determines the time it takes for the compressor to return to normal volume level; and attack tells the compressor when to start working, or how much or how little transient to let through before the compressor clamps down on the signal.
In short, threshold tells the compressor when to work, attack tells it how fast to work, ratio tells it how hard to work, and release tells it when to stop working.
A compressor can emphasize or deemphasize attack; increase overall average level of the sustain portion of the envelope, and create a more consistent dynamic range, which has the illusion of increasing sustain. This is a common perception of the effects of compression on a bass guitar.
Sustainers are specialized compressors. That is to say that their basic operating principle is gain reduction, but they are tweaked to provide a higher overall average level and a long release.
In short, they boost the low-level sounds and reduce the louder signals to produce a more even output. The long release boosts the overall level over time, so that instead of a natural decay, the sustainer turns up the volume as the note dies down, and this creates the effect of long sustain.
A noise gate only affects the release portion of a sound and is used to control rising amp noise as a sound decays. Named for its function, the gate opens and closes just like the gate of a fence.
Gates have attack, threshold, release, or range controls. Like the compressor, the attack control determines how fast the gate opens. When a signal falls below the threshold, the gate starts to close. Range determines whether the gate closes entirely or how much the signal is attenuated. Similarly, a release control determines how slowly or quickly the gate closes.
One of the problems associated with gates is called, “chatter,” which is the rapid opening and closing of the gate as a decaying signal fluctuates around the threshold. Another problem with noise gates is the time it takes for the gate to open, which can cost you some attack or transients.
Since compressors increase overall average level, they increase noise as well, which is why gates are built in to some compressors, such as the channel strips on SSL G Series and Neve R88 consoles.
There are other solutions to noise reduction, which use the principles of downward expansion.
An expander is the opposite of a compressor. Compressors decrease dynamic range, whereas expanders increase dynamic range. The expander does not pass sounds that fall below the threshold.
To better understand the difference, think of it this way: a compressor lowers the bridge; an expander lowers the river. The main difference between a noise gate and a downward expander is that the expander eliminates gate chatter, since all sounds that fall below the threshold are simply not heard.
Noise suppresser pedals use technologies based on downward expansion as their primary operating principle. Two examples would be Rocktron’s Hush pedals and iSP Technologies’ Decimator pedals. Both were designed by Buck Waller, who sold his interests in Rocktron and went on to found iSP.
How Guitar Equalizer Pedals Work
An equalizer selectively amplifies or attenuates selectable frequency ranges. There are three types of equalizer pedals: graphic, parametric, and semi-parametric.
Some EQ pedals also have filters, otherwise known as shelving EQs. A high-pass filter allows all frequencies above a set point to pass, while a low-pass filter allows all frequencies below a set frequency to pass. Typical settings for a high-pass filter are 60, 80, and 120Hz. Their purpose is to filter out low-end noise and rumble.
Graphic equalizers are divided into several narrow frequency bands, each controlled by a slider control. Graphic EQs for guitar can have anywhere from 5, 7, or 10 bands. Each band controls a narrow frequency range.
Graphic EQs are designed for problem solving insofar as they can notch out a problem frequency without affecting the frequencies around it. Well, not too much, anyway. We’re all familiar with the smiley-face EQ, which scoops out midrange frequencies in hopes of providing clarity.
The funny thing is that despite the name, “graphic,” the physical position of the sliders does not accurately represent the way the frequency range is being equalized. (It’s not really smiling.)
Rather than a series of narrow fixed bands, a parametric EQ has three or four sweepable frequency bands that have a certain amount of overlap. Each has a gain control for boost or cut. Also, each band has a variable “Q” or bandwidth control.
A semi-parametric EQ doesn’t have a Q control. The most common frequency bands are low, mid, and high. Some have an additional frequency band, with midrange being divided into low and high mids. Semi-parametric equalizers are for tone shaping, not correction.
EQ selectively amplifies specific frequencies; therefore, it makes sense that we start with the natural waveform and then apply EQ. After all, it wouldn’t make sense to equalize a sound before we hear it, which brings up an important concept with EQ; think about what you’d like to equalize and realize that it changes the sound of the unit ahead of it, and the phase of the waveform and gain level the next pedal in the chain sees.
Despite the fact that some say EQ should come first in the chain, you already have EQ on your guitar and amp. With a solidbody guitar going into overdrive, distortion, modulation, and delay, it doesn’t make that much sense to EQ the sound of the guitar before it sees any of these sound-altering components.
The only reason to use EQ first in the chain would be if you were playing a guitar prone to unwanted feedback, such as an acoustic-electric, hollow- or semi-hollow-body guitar. In this case you’d use the graphic EQ after the guitar to “ring out” your sound by cutting a narrow band where feedback occurs—hopefully without damaging your overall signal.
How Modulation Pedals Work
Modulation pedals use a signal or a voltage to alter another signal. This is accomplished by splitting the input signal and altering the relationship of the two signals in terms of phase (time delay) and pitch. And that brings up an interesting and apparent conflict.
If reverbs and delays are time-based effects, how do they differ from modulation effects, since delays are their basic operating principle? Let’s talk about the three most common types of modulation effects: flanger, chorus, and phase shifter. Then, we’ll explain time-based effects, after which, we’ll know the answer to that question.
Flanging was an accidental discovery that first appeared on the song, “The Big Hurt” by Toni Fisher in 1957. During the session, someone accidentally sat on one of the reels on tape machine slowing down the tape. When they stood up letting tape speed resume to normal, it created the effect we now know as flanging.
Upon hearing the effect, the band wanted it on the record. The song climbed to number three on the charts, largely based on this new sound. For years afterward, engineers duplicated the effect of speeding up and slowing down tape by putting their fingers on the metal flanges that held the tape reel together; hence the name, “flanging.”
Eventually, sore fingers and blisters dictated finding a new means of creating the effect, which was accomplished with a digital delay. Digital delays have a control called “feedback,” which takes the delay’s output signal and feeds it back into the input. Delay times also relate to pitch. The shorter the delay, the higher the pitch, the longer the delay, the lower the pitch.
If you set a digital clock to sweep the delay between 1ms and 9ms, you get the effect we call flanging. The wider you set the delay range, the greater the sweep in frequencies, the more feedback, the more intense the sweep.
Working on the same principal as flangers, if you set a narrow sweep between 2 and 3ms, you get the chorusing effect. Chorus effects have an additional delay added for doubling or fattening.
Again, working on the same principle as flangers and chorus pedals, if you set the secondary signal to sweep between 0 and 1ms, you get the effect called phasing.
In essence, chorus, phase shift, and flanging are short delays with feedback. They tend to obscure sounds, making them spacey and atmospheric. Knowing this will help you decide where to place them in your pedal chain, or at least ask the right questions; i.e. do you want an obscured sound feeding your overdrive pedal, or vice versa?
Other modulation effects include octave pedals, tremelos, wah wah pedals, and harmonizers.
How Time-Based Effects Work
Originally, recording engineers discovered that you could hear a delay by recording a sound at the record head and listening at the playback head. Varying the tape speed changed that rate of echo.
The gold standard for tape echo was the Maestro Echoplex, followed later on by the Roland Space Echo. The downside of tape echo is that each time you record to the tape loop, you lose high frequencies and tape hiss increases.
Eventually, the effect was created with solid-state analog delays by putting a series of capacitors in the signal path. Capacitors take time to charge and discharge; one “empties” signal into the next, which is why they are called bucket brigade devices. Digital delays use a clock pulse to set the time of the delay.
Reverb, Delay, and Echo Effects
These effects emulate what happens to sound reflecting off a surface in a room. Since sound travels at approximately 1,130 feet per second, one millisecond of delay is equal to sound travelling approximately one foot in reality space. Therefore, if you set a delay at 25ms, it means that the sound source has the illusion of being 25 feet away.
Different models of delay units have varying controls. This is true of both digital and analog delay pedals. However, the most defining are delay time and feedback.
Delay time is set in milliseconds. As we mentioned earlier, feedback, takes the delay’s output signal and feeds it back into the input. The amount of feedback determines the number of individual echoes you hear (provided the delay time is long enough. Feedback can be set from one echo to infinite repeat. Infinite feedback can get pretty gnarly if you’re not careful, but it can also be useful for creating cavernous ambient effects.
Loopers also fall into the category of time-based effects, but they do not attempt to duplicate the effects of sound in reality space. A looper samples, or records a signal for a long period of time (up to 40 seconds) and repeats it, like a long delay with feedback maxed out for infinite echoes. Loopers also let you control the timing of the loop so you can play along in time with them and create complex phrase loops.
Want to have one single pedal that provides a seemingly endless wide range of sounds? Multi-effects pedals offer an all-in-one solution for guitarists who want a compact unit instead of a pedal board filled with 50 different individual pedals.
These multi-effects units come equipped with user-friendly interfaces and customizable presets to help you dial in pretty complex tones, especially when paired with amp modeling effects. We’ll dive deeper into these pedals in a future article.
And right about here is a good place to stop. We covered a lot of ground breaking down all the different categories of guitar effects pedals.
We have a whole other article talking about guitar pedal order. In this article we talk about how the pedals interact depending on where they are placed in the signal chain, which will make it clearer in terms of how to place pedals more specifically. For example, which comes first, compressor or EQ, etc. We also talk about true bypass vs. buffered bypass, specialty pedals and where to put them, digital modeling effects, how to mix your dry signal with your wet signal, and much more. Check it out here.