Today, in what has been called the “Golden Age” of effects pedals, a musician has access to an extremely wide variety of sound altering devices, the categorization of which can be challenging. One approach is to group them based on how they alter the sound applied to them: amplitude or VOLUME controlling, TIME-based, timbre (or TONE) altering and FILTERing, and PITCH harmonizing and modulating effects. Some popular effects (first heard in the Hammond Organ in the 1930s) are known as tremolo, vibrato, chorus, and reverb.
Dynamic, amplitude or volume effects were the earliest effects to be introduced to guitarists. They first appeared in the 1940s as simple on/off switch boards. Since that time, musicians have considered them an essential part of the pedal board set-up. By the 1950s, the design of volume pedals had significantly improved with capabilities that allowed for the smooth control of the volume and timbre or tone.
- TREMOLO: The tremolo is used to produce a periodic variation in the volume of a note or chord. Some say it creates a “shuddering effect” or “sweeping transitions of sound.” It is different from the tremolo bar on a guitar which creates a vibrato or pitch-bending effect, and is reminiscent of the rotating Leslie speaker sound. This effect can be heard in the Beatles’ “Something,” Eric Clapton’s “While My Guitar Gently Weeps” and Jimi Hendrix’s “Angel.”
- COMPRESSION:The compression pedal reduces the dynamic range of the signal to produce a balanced volume output. It functions like an automatic volume control which reduces loud sounds over a certain level. It results in an artistic style that can be described as “plucky” or “clicky” and is often heard in today’s country music sound.
- BOOST: A boost pedal amplifies the sound/volume. It is often used on stage to boost a guitar solo.
Delay devices first appeared in the late 1940s and were created by loops of tape or other recording media prominent in the experimental and avant-garde music scene. The delay time was determined by the distance between the heads and the tape speed. Experiments with magnetic tape and its application in composition, coupled with the development of electronic effects for the Hammond Organ, eventually paved the way to modern effects pedals.
- ECHO: The delay effect actually simulates an echo of a sound. It can create the magically expansive sound of the interior of a cathedral. It is easily heard in the guitar riff in U2’s song “Where the Streets Have No Name.”
- CHORUS: The chorus effect divides the sound signal into two parts. One signal is slowed down and slightly detuned, and then is mixed with the original dry signal. This process creates a rich effect which, interestingly, occurs naturally in a choir of singers or an orchestra. The sound has been described as “thick,” “lush,” and “wide.”
- REVERSE DELAY: The reverse delay plays samples of music backwards imitating the practice of flipping the tape over during recording sessions in the 1960s.
- REVERB: The reverb effect (from the word “reverberation”) is the result of many echoes with differing delay times that feed back upon each other as if the sound were “reverberating” in an acoustically reflective space.
- LOOPING: This pedal allows the musician to record several layers of musical phrases which are then played back over and over (i.e., “looped”). Thus, the musician can create a rich musical texture over which they can solo, in essence creating a “one man band.” Looping is a significant element in sampling, hip-hop, and ambient music. Cellist Zoe Keating is known for her innovative use of looping to create sonic atmospheres with her amplified instrument.
Fuzz, distortion and overdrive are perhaps some of the better known and most popular effects associated with the musical styles of the 1960s. They were often a result of accidents in which the guitar amplifier or its vacuum tube was damaged. Some musicians decided they liked the accidental sound, and recorded music that way.
- DISTORTION & OVERDRIVE: This effect adds sustain, additional harmonics and overtones to the signal, creating a richer sound, sometimes referred to as “thick walls of sound.” There are many levels of distortion and overdrive. On one end of the spectrum, this effect adds a sort of “warmth” to the original tone. A good example is Chuck Berry’s 1955 hit, “Maybellene.” In the 1960s, this effect permeated the sound of garage bands and psychedelic music. At the other extreme, distortion and overdrive can create the screaming “bite,” “grit,” and “crunch” heard in the late 1980s and in genres such as punk, industrial, grunge, and metal.
- FUZZ: This pedal creates an even more distorted sound than a standard distortion pedal or overdrive. The Rolling Stones’ “I Can’t Get No Satisfaction” released in 1965 made the fuzz pedal one of the most sought-after effects boxes. The fuzz effect is also heard in the era-famous tunes “2,000 Pound Bee” (The Ventures, 1962) and “In-A-Gadda-Da-Vida” (Iron Butterfly, 1968). As is often the case, this sound was an accidental discovery and the result of faulty recording equipment—Nashville session musician Grady Martin “discovered” the sound while recording Marty Robbins’ hit, “Don’t Worry.”
Filters in general are circuits that alter the frequency content of signals passing through them. Lowpass filters allow frequency below their designed cutoff to pass through and thus reduce the level of higher frequencies; highpass filters allow only higher frequencies to pass through. The development of filtering effects is closely linked with radio technology and military applications. The major concern of these applications was the transmission of the sound content of a person’s voice without losing intelligibility and recognisability. Eventually, this technology was creatively adopted for electronic music experiments. Some most noted applications of filters could be found in early synthesizers in university music studios.
- WAH-WAH: The classic example of the filter-based effect is the wah-wah pedal that first became commercially available through the Warwick Electronics Inc./Thomas Organ Company (who had recently bought the Vox company name). The wah-wah alters the tone of the signal to create a distinctive effect, intended to mimic the human voice when saying the word “wah.” Some famous examples can be heard in Cream’s “White Room,” Jimi Hendrix’s “Voodoo Child,” in many Motown hits including the Temptations’ “Cloud Nine” and in the funk classic, “Theme from Shaft.”
- AUTO-WAH: The effect creates an audio effect similar to that of the foot-controlled wah-wah pedal, except that the effect is voltage controllable and created in response to the volume of the input sound. Notable recordings featuring the auto wah include U2’s “Mysterious Ways” and Stevie Wonder’s “Higher Ground.”
Pitch-based effects are closely related to the devices for frequency and amplitude modulation that were first used for telephone and radio transmission. After World War II, as applications and technology improved, these devices found their way to electronic studios and into electronic music in the 1950s. Their production as compact effects boxes, including in the form of stompboxes, became commercially available in the 1970s. Pitch harmonizers and modulation effects shift the pitch to create new harmonies, play parallel harmonies, orharmonies that add massive dissonance, making the guitar sound like a completely different instrument.
- PHASER: This effect is created by splitting a signal into two paths that are out of phase. The result is described as a “shimmering, spacey sound” or a “swooshing effect reminiscent of the sound of a jet.” Frequently used in the records of the late 60s in a variety of 70’s popular music genres it can be heard on Jimi Hendrix’s “A Merman I Should Turn to Be.” Eddie Van Halen is known for phaser in his signature sound.
- FLANGER: This effect is similar to the phaser but generates a sound that is more like an airplane taking off/landing, or a something resembling a tape out of sync. It was very common in analog recording studios and can be heard in Ted Nugent’s “Stranglehold,” & Pink Floyd’s “The Wall.”
- OCTAVE:This effect creates sounds one or two octaves above or below the note that is played. When mixed with the original signal, the lower octaves can make a guitar sound like a thundering pipe organ or a bass.
- HARMONIZER: This effect takes a pitch and manipulates it to create additional pitches to harmonize with it.
- RING MODULATOR: This effect was used by electronic music pioneers and avant- garde musicians in the 50s. The ring modulator is versatile and can be used on guitars, synthesizers, and drums. It can produce a metallic, bell-like effect, or a grinding, squealing discordant noise. It can also be used to dramatically alter voices.