Effects unit
An effects unit, effects processor, or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing.
Common effects include distortion/overdrive, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects, such as reverb and delay, which create echoing sounds and emulate the sound of different spaces.
Most modern effects use solid-state electronics or digital signal processors. Some effects, particularly older ones such as Leslie speakers and spring reverbs, use mechanical components or vacuum tubes. Effects are often used as [|stompboxes], typically placed on the floor and controlled with footswitches. They may also be built into guitar amplifiers, instruments, [|tabletop units] designed for DJs and record producers, and [|rackmounts], and are widely used as audio plug-ins in such common formats as VST, AAX, and AU.
Musicians, audio engineers and record producers use effects units during live performances or in the studio, typically with electric guitar, bass guitar, electronic keyboard or electric piano. While effects are most frequently used with electric or electronic instruments, they can be used with any audio source, such as acoustic instruments, drums, and vocals.
Terminology
An effects unit is also called an effect box, effects device, effects processor or simply an effect. The abbreviation F/X or FX is sometimes used. A pedal-style unit may be called a stomp box, stompbox, effects pedal or pedal. Unprocessed audio coming into an effects unit is referred to as dry, while the processed audio output is referred to as wet.A musician bringing many pedals to a live show or recording session often mounts the pedals on a guitar pedalboard, to reduce set-up and tear-down time and, for pedalboards with lids, protect the pedals during transportation. When a musician has multiple effects in a rack mounted road case, this case may be called an effects rack or rig. When rackmounted effects are mounted in a roadcase, this also speeds up a musician's set-up and tear-down time, because all of the effects can be connected together inside the rack case.
Form factors
Effects units are available in a variety of form factors. Stompboxes are used in both live performance and studio recording. Rackmount devices saw a heavy usage during the later 20th century, due to their superior processing power and desirable tones as compared to pedal-style units. However, by the 21st century, with the advent of digital plugins and more powerful stompboxes for live usage, the use of rack-mounted effect units has declined. An effects unit can consist of analog or digital electronics or a combination of the two. During a live performance, the effect is plugged into the electrical signal path of the instrument. In the studio, an instrument or another sound source — possibly an auxiliary output of a mixer or a DAW — is patched into the effect. Whatever the form factor, effects units are part of a studio or musician's outboard gear.Stompboxes
Stompboxes are small plastic or metal chassis that usually lie on the floor or in a pedalboard to be operated by the user's feet. Pedals are often rectangle-shaped, but there are a range of other shapes. Typical simple stompboxes have a single footswitch, one to three potentiometers for controlling the effect, and a single LED that indicates if the effect is on. A typical distortion or overdrive pedal's three potentiometers, for example, control the level or intensity of the distortion effect, the tone of the effected signal and the output level of the effected signal. Depending on the type of pedal, the potentiometers may control different parameters of the effect. For a chorus effect, for example, the knobs may control the depth and speed of the effect. Complex stompboxes may have multiple footswitches, many knobs, additional switches or buttons that are operated with the fingers, and an alphanumeric LED display that indicates the status of the effect with short acronyms.An is formed by connecting two or more stompboxes forming a signal chain. Effect chains are typically created between the guitar and the amp or between the preamplifier and the power amp. When a pedal is off or inactive, the electric audio signal coming into the pedal diverts onto a bypass, an unaltered dry signal that continues on to other effects down the chain. In this way, a musician can combine effects within a chain in a variety of ways without having to reconnect boxes during a performance.
A controller or effects management system lets the musician create multiple effect chains, so they can select one or several chains by tapping a single switch. The switches are usually organized in a row or a simple grid.
It is common to put [|compression], wah and overdrive pedals at the start of the chain; modulation in the middle; and time-based units (delay/echo, reverb at the end. When using many effects, unwanted noise and hum can be introduced into the sound. Some performers use a [|noise gate pedal] at the end of a chain to reduce unwanted noise and hum introduced by overdrive units or vintage gear.
Rackmounts
Rackmount effects units are typically built in a thin metal chassis with rack ears designed to be screw-mounted into the rack rails of a 19-inch rack that is standard to the music technology industry. Rackmount effects have a standardized 19-inch width, and height of 1 or more rack unit. Devices that are less than 19 inches wide can sometimes be made rackmount-compatible via special rackmount adapters.A rackmount effects unit may contain electronic circuitry identical to a stompbox's, although its circuits are typically more complex. Unlike stompboxes, rackmounts usually have several different types of effects. Rackmount effects units are controlled by knobs, switches or buttons on their front panel, and often remote-controllable by a MIDI digital control interface or pedal-style foot controller.
Rackmount effects units are most commonly used in recording studios and front of house live sound mixing situations. Musicians may use them in place of stompboxes, as use of a rack can offer space for conveniently mounting additional rackmount equipment or accessories. Rackmounted effects units are typically mounted in a rack, which may be housed within a road case, a durable case with removable access panels that protect the equipment within during transportation. Because of this, rackmount effect units are not always designed with durable protective features such as corner protectors which are used on stompboxes and amps that are designed to be transported as standalone units.
Multi-effects and tabletop units
A multi-effects device is a single electronics effects pedal or rackmount device that contains many different electronic effects. multi-effects devices allow users to preset combinations of different effects, allowing musicians quick on-stage access to different effects combinations. Multi-effects units typically have a range of distortion, chorus, flanger, phaser, delay, looper and reverb effects. Pedal-style multi-effects range from fairly inexpensive stompboxes that contain two pedals and a few knobs to control the effects to large, expensive floor units with many pedals and knobs. Rack-mounted multi-effects units may be mounted in the same rack as preamplifiers and power amplifiers.A tabletop unit is a type of multi-effects device that sits on a desk and is controlled manually. One such example is the Pod guitar amplifier modeler. Digital effects designed for DJs are often sold in tabletop models, so that the units can be placed alongside a DJ mixer, turntables and scratching gear.
Built-in units
Effects are often incorporated into instrument amplifiers and even some types of instruments. Electric guitar amplifiers often have built-in reverb, chorus and distortion, while acoustic guitar and keyboard amplifiers tend to only have built-in reverb. Some acoustic instrument amplifiers have reverb, chorus, compression and equalization effects. Vintage guitar amps typically have tremolo and vibrato effects, and sometimes reverb. The Fender Bandmaster Reverb amp, for example, had built-in reverb and vibrato. Built-in effects may offer the user less control than standalone pedals or rackmounted units. For example, on some lower- to mid-priced bass amplifiers, the only control on the audio compression effect is a button or switch to turn it on or off, or a single knob. In contrast, a pedal or rackmounted unit would typically provide ratio, threshold and attack controls or other options to allow the user additional control over the compression.Some guitar amplifiers have built-in multi-effects units or digital amplifier modeling effects. Bass amplifiers are less likely to have built-in effects, although some may have a compressor/limiter or fuzz bass effect.
Instruments with built-in effects include Hammond organs, electronic organs, electronic pianos and digital synthesizers. Built-in effects for keyboards typically include reverb, chorus and, for Hammond organ, vibrato. Many clonewheel organs include an overdrive effect. Occasionally, acoustic-electric and electric guitars will have built-in effects, such as a preamp or equalizer.