Guitar Effects 101

This article is a copy of my workshop notes handouts for a series of clinics I did with Roland/Boss. Info is short and to the point as demos and examples were done live, but it manages to cover all the basics.

Guitar Effects

Probably the main thing to understand about effects is that an effect modifies the sound it receives. Each has its own particular sound, although some effects can sound similar to others.

Effects formats: Compact pedals, floor multi-effects & rack units

There are three main formats that effects appear in: Compact pedals, floor multi-effects & rack mounted units

Compact pedals

Compact pedals are designed specifically for guitarists and are made to go in between the guitar and the amplifier.  They are small, and usually perform only one type of effect, such as distortion or delay. They are designed to handle the low signal levels that a guitar produces, and are not suitable for use in an amplifier’s effect loop or with line level signals.

Rack mounted

Rack mounted effects are larger and designed to bolt into the industry standard 19” (48cm) rack cases. Originally they were designed for use in recording studios and are often of a higher quality and more powerful than floor pedals. Rack effects are frequently multi-effects – having more than one different type of effect in the same box, and usually having more options and controls than pedal effects.

Floor multi-effects

As with compact pedals, floor multi-effects are designed specifically for guitarists. They are usually much more powerful, and frequently include amplifier, speaker and even microphone modelling as well as a whole array of guitar specific effects. One major benefit of floor multi-effects is that they include foot pedals to switch sounds with, as well as rocker pedals suitable for volume control and wah duties.

Multi-effects

It is increasingly common to find multi-effect units which contain any number of effects in one convenient unit. As already mentioned, these can be in the form of a floor unit with foot switches and rocker controls or rack mounted units with MIDI control which are controlled via any MIDI capable footswitch.

The main attraction of multi-effect units is that effect configurations and settings can be stored in convenient memory locations called patches. When a patch is selected it recalls all the different effects used in the patch, the effect order and all the individual settings used by each effect. This ability can save a lot of the ‘tap dancing’ and knob tweaking which is necessary to control a number of separate floor pedals.

Many multi-effect units also contain modelled amplifiers and speaker simulators, often making them the only device needed for a gig – take your multi-effect and guitar and plug straight into the PA and monitor system. If you prefer to use just the effects and use a guitar amplifier and speakers onstage, just write your patches with the amp and speaker simulations turned off.

Another advantage of multi-effect units is that they are cost effective, costing many times less than all the individual effects together. However, it is more of an initial outlay and you cannot buy one effect at a time as you can with single pedals.

One disadvantage of multi-effect units is that it is a steep learning curve for the beginner, to suddenly get a huge variety of effects in one go. The way to get around this is to experiment with one effect at a time, learning how to use it effectively before moving on to the next effect. There is also the possibility that you will prefer a particular effect from another manufacturer, but most good Multi-effects will allow you to insert a separate pedal into an effect loop, and then switch the loop – and thus the effect – in and out as required.

Effect Chains

When more than one effect are used together

Using effects in series or parallel

The most common way to connect effects is in series, where the output of one effect feeds the input of the next. There is another, less often used option, which is to connect then in parallel, where the signal is buffered (powered by a preamp), the buffered signal is then used to drive both effects inputs. The outputs of the two effects are then either mixed together or each is taken to a separate amplifier. This means that a wide array of ‘blended’ sounds can be obtained, e.g. an overdriven sound mixed with a clean, chorused sound.

Effect types

Effects fall into a number of broad-based categories, depending on how they achieve the sound they create. These are:

  • Distortion – which provide effects similar to overdriven amplifiers
  • EQ/Tone – which change the tone of the guitar by changing the volume of different frequencies
  • Modulation – which apply various pulsing effects
  • Time-based – which use time delayed sounds
  • Pitch-based – which change the pitch of the instrument
  • Level/dynamics control – which control the level of the guitar or the dynamic range (the range of volumes from quietest to loudest)

Effect placement

In a chain of effects (often called the signal chain) there is often a particular order of effects which will work best, or is most commonly used. These are listed with the effect descriptions below. However, this is not set in stone and it pays to experiment with the order of your pedals. Swap them around and seeing what the results are and what works for you. The more you learn about the sounds they create and how they react with each other, the easier you will come to creating your own sounds.

The different effects and what each does

Distortion effects

Overdrive, distortion & fuzz

Sound Effect Details

These effects are intended to produce the sound of an overdriven valve amplifier, pushed well into its clipping region. This is the most commonly used guitar effect of all.

In use

Overdrive is usually obtained with a technique called soft clipping, where gain is reduced beyond the clipping point, giving a smoother, more natural sounding effect, with even order harmonics (which are harmonically related to the note). Overdrive responds well to dynamics – being less intense with softer playing and increasing in effect as the guitar is played harder.

Distortion uses hard clipping, which makes for a harsher sound with odd order harmonics. There is usually more gain than with overdrive.

Fuzz is the original distortion effect which is characterised by extreme levels of drive and odd order harmonics.

Controls

Gain (often labelled as Drive) controls the amount of overdrive

Tone – compensates for additional highs created by the clipping process. There are sometimes expanded tone controls, such as Bass, middle and treble.

Volume (or Level) – balances the effect volume with the bypassed level. It can also be used to boost the signal for solos.

Placement

Overdrive is usually placed after a compressor in the signal chain, this makes for a more sustained overdrive sound. However, will usually be before time-based effects like delays and reverb.

Guitar amplifiers & speakers

Guitar amplifiers and their speakers can be considered as distortion effects (and also as tone modifiers!) Usage and placement are the same as other distortion effects.

EQ/Tone effects

Wah-wah

Sound Effect Details

The wah pedal produces an effect like the vocal ‘waa’ sound which can be very expressive.

In use

A wah creates its effect by a creating a ‘peak’ in the frequency spectrum (by boosting the level of a narrow range of frequencies) and moving this peak up and down the frequency spectrum.

Variations
There are three variations of wah effect; the pedal wah, the touch wah and the auto wah.

The pedal wah is controlled manually by moving a rocker pedal similar to a volume pedal with your foot. A wah pedal can also be used as a distinctive sounding ‘tone control’ if the rocker is left set at one position.

The ‘touch wah’ is an automatic wah. It moves the peak up or down depending on the volume of the guitar signal. As you play a note, its natural volume swell causes the peak to move up the spectrum and as the note dies out it moves back down again.

The second automatic wah effect is the ‘auto wah’, which moves the peak at a predetermined speed. This is actually a type of modulation effect, as it uses a second waveform to modulate the signal.

Controls

The controls on a wah pedal are very basic: there is the rocker pedal and a bypass switch to turn the effect on and off.

For an auto wah, there will be a rate control which controls the speed that the peak is swept through the frequency range; a frequency control, which sets where in the frequency range the effect operates; and a depth control, which sets how wide a range of frequencies is covered.

The touch wah has similar controls to the auto wah but with a sensitivity control instead of a rate, which sets how the effect responds to different volumes.

Placement

Wahs are usually placed very early in the signal chain, although the effect can also be used after an overdrive or a distortion effect to create a thicker sound. A touch wah needs to be placed before compressors, limiters or volume controls, as these all affect the way it works.

Graphic Equalisers

Sound Effect Details

This effect is designed to give more tone control than is possible with the guitar or amplifier controls.

In use

Graphic equalisers use sliders to control the level of specific fixed frequencies, called bands.  These provide a graphic representation of the overall frequency response.

Controls

Frequency sliders – one for each frequency to be modified.

Level control – allows you to compensate for any overall loudness changes made by the tone changes.

Placement

Equalisers can be placed almost anywhere in the signal chain, but are usually placed after compressors.

Modulation effects

Phaser

Sound Effect Details

Phasers have a characteristic sweeping, ‘whooshing’ sound. The effect can be quite subtle.

In use

This effect is created by moving notches (cuts in level across a narrow range of frequencies – the opposite of a peak), up and down the frequency spectrum automatically at a set rate.

Controls

Speed or rate – controls how fast the notches are moved

Depth – controls how far through the frequency spectrum the notches are moved

Resonance – controls the level of the frequency peaks

Placement

The effect will be more subtle when used on a clean sound and will become more obvious if it is placed after a distortion effect. A compressor is sometimes used after a phaser, to even out the volume variation this effect can create.

Chorus

Sound Effect Details

Chorus works the same way as flanging and has a similar sound. However, it uses a longer delay than flanging, so there is a perception of “spaciousness”, which is particularly good for stereo. There is also little or no feedback, so the effect is more subtle.

In use

Vibrato mixes a varying delayed signal with the original to produce a large number of harmonically related notches in the frequency response.

Controls

Speed or rate – controls how fast the notches are moved

Depth – controls how far through the frequency spectrum the notches are moved

Pre-Delay – controls the delay time

Tone controls – are sometimes available

Intensity (or Effect or Mix) controls the level of the delayed signal, and consequently, the depth of the frequency notches and level of the delay

Placement

Usually after compression and overdrive, but before time-based effects like delays and reverb.

Flanger

Sound Effect Details

Flangers mix a varying delayed signal with the original sound to produce a series of notches in the frequency response. This effect is similar to a phaser but with more resonance, which adds colour.

In use

The important difference between flanging and phasing is that a flanger produces a large number of notches, and the peaks between those notches are harmonically (musically) related. A phaser produces a small number of notches that are evenly spread across the frequency spectrum. With high resonance, you get the “jet plane” effect.

Controls

Speed or rate – controls how fast the notches are moved

Depth – controls how far through the frequency spectrum the notches are moved

Resonance – controls the level of the frequency peaks

Placement

Usually after compression and overdrive, but before time-based effects like delays and reverb.

Tremolo

Sound Effect Details

This modulates the guitar volume, like rapidly turning the volume control up and down.

In use

Different versions use different waveforms to modulate the volume level. Sine waves give a smooth effect as the volume fades in and fades out again. Saw wave forms offer a less pulsating sound, square waves turn the sound off and on very quickly. Some tremolo pedals allow you to select the waveform to use for modulation.

Fender incorrectly labels this sound as vibrato on their amps.

Controls

Speed – controls how fast the volume varies

Depth – controls how much the volume varies

Waveform – chooses the waveform to use for modulation

Placement

Will work best placed after compression, but before time-based effects like delays and reverb.

Panning

Sound Effect Details

Panning is a stereo effect which moves the signal from left to right in stereo.

In use

It is basically two tremolo effects, one for each of the left and right channels. They are linked so that when volume is high in one channel it is low in the other, and vice-versa.

Controls

Speed – controls how fast the sound moves from one side to the other

Depth – controls how far the sound moves from one side to the other

Waveform – chooses the waveform to use for modulation

Placement

Will work best placed after compression, but before time-based effects like delays and reverb.

Vibrato

Sound Effect Details

Vibrato varies the pitch smoothly between slightly flat and sharp. similar to the fingerboard technique of string bending, moving a tremolo or the effect gained with a rotary speaker..

In use

Vibrato is obtained by modulating the pitch of a signal. Fender amps have an effect labelled vibrato which is actually volume modulation, or tremolo (see below).

Controls

Rate and Depth – how fast and how far pitch is changed

Delay – often the effect is triggered automatically, and this sets how long it takes to reach the set depth

Placement

Will work best placed after compression and overdrive pedals but before time-based effects like delays and reverb.

Time-based effects

Delays

Sound Effect Details

Delay is an echo effect, it repeats the original sound one or more times, adding more notes at later times than the original – can be like having a second guitarist play along with the first.

In use

Early delays were tape based, using a record head and multiple playback heads. Modern delays are digital, where the sound is converted to ones and zeros and stored in memory so that it can be copied and played back repeatedly at later times. The older tape units lost treble the more repeats there were, while the modern units can reproduce a perfect copy every time.

More sophisticated units offer multiple taps, with options to position taps anywhere between left and right output channels for interesting stereo effects.

One popular stereo effect is ping-pong delay – where the repeat sounds as if it bounces from left to right as it fades out.  Another is doubling – where a single repeat at a short delay time (about 50mS) at nearly the same level as the original sounds like two players playing the same thing in near-perfect unison.  By increasing the delay a little more (about 100ms) you get a slap-back echo effect. Very short delay times (1-12mS) produce phase cancellation at fixed frequencies and effectively change the tone.

Controls

Delay time – sets the amount of time between the original sound and the repeat

Delay level – sets the volume of the repeated sound

Feedback – sets the number of repeats

Placement

Delay works best after all other effects except reverb. Digital units should always be placed after noise gates, as they produce very little noise and the effects ‘tail’ persists after the gate has closed, making for a more natural sound.

Reverb

Sound Effect Details

Reverb (or reverberation) is the persistence of sound you hear in a room where sound bounces around the room for a while after the initial sound stops. It is made up of a very large number of repeats, with varying levels and tones over time.

In use

Guitar amps with built in reverb use a spring reverb, where at least one long spring is connected to two transducers. The first transducer acts as a speaker – playing the sound, which reverberates backwards and forwards through the spring. The second transducer picks up the resulting sound and mixes it back with the original signal.

Digital reverbs usually offer you a choice of different sized rooms and halls, studio effects such as plate, chamber and reverse reverbs, and sometimes emulations of guitar spring reverbs.

Better delay units may feature early reflections which simulate the stage situation where the reflection from the wall behind the player is heard first ad a distinct short echo.

Controls

Decay time – sets how long it takes the reverb to die away to nothing

Predelay – sets the amount of time between the original sound and the first reflection

Level – controls the overall volume and tone of the reverb

Tone – Changes the tonal balance of the reflections

Early reflection delay – the amount of time before the early reflection is heard

Early reflection level – the volume of the early reflection

Placement

Reverb is usually the last effect in the signal chain. Digital units should always be placed after noise gates, as they produce very little noise and the effects ‘tail’ persists after the gate has closed, making for a more natural sound.

Pitch-based effects

Octave dividers

Sound Effect Details

Octave dividers are simple pitch shifters, which create a signal one or two octaves below the signal at the input, then combine it with the original signal.

In use

They only work on one note at a time, becoming confused if they encounter more. The octaved signal is a square wave, which is similar to a distorted sound.

Controls

Range – sets how many octaves below the original the generated signal is

Octave level – sets the level of the generated signal

Level – sets the level of the combined signal

Placement

Octave dividers work best after compressors as they are more stable with a steady level.

Pitch shifters

Sound Effect Details

Add one or more voices to the notes to what you are already playing, similar to an octave divider or harmoniser. However with pitch shifters you set the harmony voices to fixed intervals, such as up seven semitones, or down five semitones.

In use

This has it’s uses such as pitch shifting an octave higher, which works for a modern sounding 12-string emulation.

Controls

Shift amount – for each voice, sets the interval to shift the pitch.

Fine tune – set for each voice, allows you to detune a voice slightly to give a thicker sounding mix

Voice level – set for each voice. Allows you to mix the harmonies with the original signal, assigning each it’s own level in the mix.

Level – controls the overall level

Placement

As with harmonisers, will work best placed after compression and overdrive pedals but before time-based effects like delays and reverb.

Harmonisers

Details

Harmonisers add one or more voices to the notes to what you are already playing, similar to an octave divider or pitch shifter, the difference is that a harmoniser offers “intelligent” chord based harmonies. This allows you to play a line in a specific key and have one or more guitars playing harmony with you – in key.

In use

Harmonisers use digital techniques that preserve the tone and timbre of your playing. This means the harmony guitars sound a lot like the original guitar sound. They may even allow you to set your own chord intervals, and apply random pitch variations or corrections to add extra realism to harmonies.

The notes generated are determined by the key (which you set), and the note you play. You could, for example, set harmonies to be a 3rd and a 5th, in the key of C major, and the harmony intervals will change to make sure that the harmony lines are always in the C major scale.

Controls

Key – which sets what key the harmony is in

Interval – set for each voice added. Sets which interval the voice will play in relation to the original note

Fine tune – set for each voice, allows you to detune a voice slightly to give a thicker sounding mix

Voice level – set for each voice. Allows you to mix the harmonies with the original signal, assigning each it’s own level in the mix.

Level – controls the overall level

Placement

Will work best placed after compression and overdrive pedals, but before time-based effects like delays and reverb.

Pitch Bend

Details

This is a digital effect which is designed to emulate a whammy bar via a rocker pedal. This is done by using a pitch shifter whose shifting amount is controlled by the rocker pedal. The output will be the effected sound only.

In use

Often these effects are combined with other digital pitch based effects such as vibrato or basic harmoniser options.

Controls

Bend range – sets how far and how fast pitch is bent and how long it takes to return to normal.

Placement

After compression, but before overdrive and time-based effects like delays and reverb works best. However after overdrive is also a viable option.

Level / dynamics control

Noise Gate

Sound Effect Details

Noise gates are in their simplest form, merely a switch which gets rid of the noise you hear during quieter parts of a signal by muting (switching off) the sound. This effectively reduces the perceived level of noise in the signal.

In use

Noise is usually masked (hidden) by the signal, as it is normally at a much lower level in comparison. However, as the signal fades away in quieter sections of the music, the noise can become noticeable and even quite annoying. A gate works by fading out the signal when it falls below a certain level (the threshold), muting both the signal and the noise. The fade  prevents notes which fall below the threshold from being cut off dead, giving the sound a natural decay.

 

There is often a separate trigger input and output. When a signal is applied to the trigger input, the gate opens (lets the signal through). This is particularly useful when used for guitar signals as you can use the pure direct guitar sound to control the gating of your noisy effects.

Controls

Threshold – sets the level below which volume is faded out.

Attack – controls how fast the gate starts working. Usually for guitar use you want it as fast as possible, and many guitar-specific units will not feature this control at all

Decay – sets how fast the gate fades the volume

Attenuation – sets how much the gate reduces the level

Placement

Is always placed after most effects which can produce noise, but before time-based effects like delays and reverb. If there is a trigger input, a compressor will go first, then to trigger input. Trigger output goes to the input of the next effect in line.

Limiter

Sound Effect Details

This effect is similar to a compressor reducing high volumes, but a limiter does not boost low level signals.

In use

They are used to tame peaks in a sound without otherwise affecting the dynamics. Not often used in guitar setups.

Controls

Threshold/Sensitivity – sets the level above which volume is cut

Attack – controls how fast the unit responds to volume increases

Release – controls at what level the effect turns off. Is usually set a little lower than the threshold

Volume (or level) – allows you to set a level to match the general loudness when the effect is bypassed.

Placement

Anywhere in the signal chain where it is needed to control peaks – often this will be near the end of the chain.

Compression

Sound Effect Details

Compressors are commonly used to control the level, by making loud passages quieter and quiet passages louder. This is useful in allowing the sound to be heard clearly in the mix. However, it is rarely an ‘obvious’ effect to the untrained ear.

In use

Compression is generally applied to a guitar to give clean sustain. The louder part of a note is cut in volume and then, as the note fades away the volume is gradually boosted.

Controls

Threshold/Sensitivity – sets the level above which volume is cut, and below which volume is boosted.

Attack – controls how fast the unit responds to volume increases

Decay – controls how slowly the unit responds to decreasing volume

Tone – compensates for a perceived treble loss, which is actually caused by the smoother volume dynamics

Volume (or level) – allows you to set a level to match the general loudness when the effect is bypassed.

Placement

Usually compression should be first in the signal chain. However, sometimes you might want to place it after filter effects like wah pedals or phasers, as they can reduce volume at some settings and placing a compressor after these effects can even out volume differences.

Volume pedal

Sound Effect Details

Simple devices which allow you to control the level of the guitar signal with your feet.

In use

Some models allow you to set a volume range, so you can adjust it to be at backing rhythm level when turned down and solo level when turned up.

Placement

Volume pedals are usually placed after any compressor. If put before a distortion pedal, it will affect how much drive you get from the pedal. If placed after the overdrive pedal, it will control the output level only.

MIDI Control

MIDI is an acronym for Musical Instrument Digital Interface, and was originally designed as a standard to allow different manufacturer’s synthesisers to communicate with each other. As MIDI applies to guitar effects, it is used to switch patches as well as turning individual effects on and off or using continuous controllers like knobs or rocker pedals to change effect parameters, such as volume, drive, etc..

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