Delay is a time-based effect that takes a signal and plays back delayed duplicates to create repeats; it is also an integral part of many other effects, for example modulation and reverb. We use delays to create a doubling effect, to create echo effects, to place a sound in a large space mimicking the pre-delay of a reverb, to generate rhythmic effects and to enhance the stereo position of tracks.

Delay parameters

• Delay time is the gap between each repeat which can be tempo-synced (see 13.1 for how to calculate)
• Part of the delayed signal is fed back into the input of the delay; the greater the feedback, the greater the number of repeats – at 0% there will be one echo, at 100% the delay will endlessly repeat
• Pan changes the stereo position of the delay / taps; filtering can change the frequency content of the repeats
• Dry / wet / mix alters the delay volume compared to the original signal (compare the level of dry vs 1^st repeat).

Types of delay

• Analogue tape delay involves recording onto a tape loop via a record head and replayed through playback heads
• There can be multiple playback heads giving multiple echoes or taps; the tape would gradually degrade, and eventually need replacing; the tape would lose some high frequency content leading to a ‘warm’ sound
• The delay time could be changed by moving the playback head or running the tape slower
• Bucket brigade delay is another analogue technology that was commonly used in 1970s guitar pedals; it works through a series of capacitors that hold charge; each stage of the delay ‘hands off’ the charge to the next stage
• The longer the delay, the more degradation of the signal and the noisier the delayed output
• Digital delay works by storing the signal in memory; because it is stored digitally, it can be manipulated
• Hardware digital delays were common in the late 1970s and 1980s, with digital delay plugins from the late 90s.

Specific delays

• Slapback delay is a single, quick (80-150ms) repeat of the sound at the same volume as the original signal
• In a ping pong delay, the delayed signal bounces back and forth between the left and right channels
• Multitap delay is a digital delay that creates complex, rhythmic patterns by using multiple independent delays
• Sample delay is used to create ADT effects – one side of the stereo field is slightly delayed (in samples not ms)
• Reverse delay works by delaying the signal then reversing the delayed signal so that it plays backwards.

The impact of delay

• Delay was first used in the 40s when experimental used tape to create repetitive echoes
• In the 60s it was used as a psychedelic effect with long, trippy delays, and in guitar solos for a sense of space
• Dub music made use of on-the-fly sends to delay to create a spacey, echoey sound
• Slapback delay was popularised by Elvis Presley and other early rock and roll artists.
• In the 70s, delay was used in progressive rock with complex and intricate delay patterns e.g. Pink Floyd
• The use of analogue delay pedals with bucket brigade delay chips became more widespread at this point
• Digital delay units became more common, allowing for more precise control over the delay time
• In early 90s EDM, delay was often used to create rhythmic stereo effects e.g. ping pong delay
• In ambient music, delay was used for ethereal soundscapes and shimmering / pulsing shoegaze music
• Used in grunge and alternative rock music to create a raw, lo-fi sound with heavy distortion and feedback
• Delay was often used to thicken vocals; for example, delay could be used to create a doubling effect, making the vocals sound layered or a quiet echo could be added to give depth
• Used in modern EDM with precise and tightly synced delay times that create complex rhythms and patterns.
• Delay is most commonly used as a DAW plugin.
• A short delay can be used to create a doubling effect on a vocal or instrument, making it sound thicker
• A longer delay can be used to create a more pronounced echo effect, often used for emphasis or for space
• Delay can help align tracks that were recorded separately, such as when using multiple microphones on a drum kit or recording a live performance to fix phase issues
• Delay can be used for rhythm, e.g. slapback delay on a vocal track or rhythmic delay effects on a guitar solo
• Delay can create a sense of movement / motion in a mix, e.g. using a ping pong delay that swaps between L & R.

Modulated delay

Modulation effects all rely on the periodic modulation of the delay time; an LFO is used to control how much the wet signal is delayed by; this amount is changed over time. An LFO (low frequency oscillator) is a control signal used to alter a parameter over time, in this case delay time. The length of delay time is what differentiates between a flanger (shorter) and a chorus (longer) effect. The wet signal is then combined with the dry signal; the signals then interact together to create the effect. Comb filtering is created when a slightly delayed version of a signal combines with the direct sound, causing destructive interference for some frequencies; this is essentially what happens on a flanger.

Modulated delay parameters

• The rate is the speed at which the modulation takes place; can either be synced to a note value in a DAW (e.g. 1/8 or quaver) or given an absolute value in hertz which gives the cycles per second
• The depth is how much the modulation affects the delay time (in the context of modulated delay effects); the greater the depth, the wider the range of delay times
• The feedback sets the amount of the effect signal that is routed back to the input of a flanger; this can change the tonal color and can make the sweeping effect more pronounced.
• The mix (dry / wet balance) determines the balance between dry and wet signals.

Types of modulated delay

• Chorus takes its name from the way it makes one voice / instrument sound like an choir / ensemble
• It delays a copy of the original signal, playing the delayed version with the clean signal – an LFO is used to delay a signal by a small and varying amount of time
• If we just listen to the wet signal, we hear this short delay as slight pitch variations – like a vibrato effect
• When combined with the dry signal, this simulates the subtle pitch and timing differences when a number of singers or instrumentalists are performing together
• The delay time of a chorus effect is normally longer than that of a flanger, meaning we hear a layering effect rather than a comb filtering effect
• Chorus is often used on clean electric guitar, fretless bass and synth pad tracks.
• For a subtle effect, the depth control is generally set quite low. If the rate control is also quite low the effect will just give a sense of life or movement to a signal, giving it a subtle detuning effect
• If the depth and rate are set quite high, a dramatic ‘bubbling’ and ‘underwater’ effect can be produced.
• Flanger works in exactly the same way as chorus but the delay time on a flanger is normally shorter than that on a chorus effect, meaning we hear frequency cancellation (‘whooshiness’) rather than layering
• Some of the effected signal is fed back into the unit using the feedback control which, when set high, generates a sweeping, pitched sound in time with the LFO
• It gives a ‘swirling’, ‘whooshing’ or ‘jet plane’ effect, depending on the rate setting and the amount of feedback
• An extreme setting gives a swirling, whooshing, ‘jet plane’ effect, and is often used on distorted guitar
• When applied to just the reverb / delay of a signal, it can produce a subtler, ‘shimmering’ effect
• Phasers sound similar to a flanger but are generally subtler
• The phaser effect is also created by combining a dry signal and a wet signal that has been modulated with an LFO and is slightly out of phase with the original
• Although phaser is included in the ‘modulated delay’ section, it is actually a filtering effect; the phase of the wet signal that is altered rather than the delay time, creating cancellation effects as the wet / dry signals combine.

The impact of modulated delay

• Modulation effects were originally created in the studio in the 1960s using two synchronised tape recorders
• The second tape recorder was slightly delayed and its signal was combined with the first; this effect was often applied to thicken up vocal tracks
• It gave the effect of delaying the ‘second’ vocal slightly and creating what is now referred to as an artificial or automatic double tracking effect; this process could also create subtle and more extreme flanger effects
• The Leslie speaker was often used with Hammond organs; this was a system of rotating speakers, which resulted in the pitch-shifting known as the Doppler effect – the source of a sound changing position relative to the listener
• This effect is now known as ‘rotary’ and was like a combination of chorus, vibrato and tremolo; this can be emulated with a phaser effect.