If your tracks sound boring, narrow, or are lacking in dimensionality, modulation effects are a great way to make them stand out. Modulation lends movement to lackluster tracks, adds depth to flat-sounding tracks, and injects width into mono tracks.
In this tutorial, we'll explore the three most common types of modulation processors — chorus, flange, and phase effects — and discuss what kinds of sounds you can create with them. We'll also provide practical examples that you can apply to your mixes.
Low-frequency Oscillators
Before we dive into modulation effects, we need to give you a quick primer on low-frequency oscillators — a.k.a. LFOs.
An LFO, which occurs below the threshold of human hearing, is a carrier waveform that's used to modify another waveform, and it's the engine behind most modulation effects.
Modulation effects employ an LFO to alter the pitch, time, or phase of your signal. The intended effect (chorus, flanger, phaser, etc.) is then achieved by mixing a doubled, modulated signal back into the original signal.
Chorus: The Secret to Lush, Shimmering Tracks
Chorus effects double and delay your signal, using a delay time of roughly 20–50 milliseconds, then mixes it back with the original signal. They then apply an LFO to modulate the pitch of the duplicated signal, yielding a subtle detuning effect.
Although chorus detunes the doubled signal, the resulting sound isn't perceived as being out of tune. Rather, it possesses a symphonic-like character, reminiscent of the sound of multiple instruments playing in unison.
Chorus is also desired because of the rich, shimmering quality it imparts — it can really make a dull track pop!
Some chorus effects, such as the fabled Tri-Stereo Chorus from the 1980s, utilize multiple doubled voices for a thicker, lusher effect. There are also pitch-shifting effects that yield a "static chorus" sound by using a fixed pitch shift (measured in cents) instead of LFO-modulated detuning.
There are a myriad of different chorus effects out there, and each features its own unique design, features, and layout. That said, whether it's housed in a pedal, a rackmount unit, or a plug-in, standard chorus effects commonly include the following controls:
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Rate controls the modulation speed.
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Depth controls the amount of pitch shift.
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Delay controls the amount of delay time.
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Mix controls how much dry signal is mixed with the chorus effect.
When used in mono, chorus is a great way to add brawny thickness, musical movement, and ear-tickling shimmer to an otherwise unremarkable source. You'll be shocked at how much life a little dab of chorus can infuse into an anemic synth line or a tragically thin guitar part!
Stereo chorus effects, which vary the LFO between channels, can transform a stagnant, dull track by imparting spatial width and dream-like dimensionality. Our ANIMATE plug-in provides you with another excellent method of achieving a wider stereo image for your narrow-sounding tracks.
Chorus sounds amazing on clean electric guitars, synth bass, pads, and organs, imbuing them with excitement, movement, and complexity. That said, it can lend an unnatural, underwater quality to vocals and high-gain guitars (which is okay if that's what you're aiming for!).
You can also crank your chorus effect's rate control to create ear-grabbing pseudo-vibrato effects.
Static pitch-shifting effects are a great way to create 1980s-style doubling for vocals, distorted guitars, and synth leads. A ubiquitous hardware pitch-shifting unit, which was commonly called a "harmonizer," was the secret studio weapon back in the decade of excess (and it was, without a doubt, used excessively!).
Flanger: Excite Your Tracks with Cool Comb Filter Effects
Like chorus, flangers double your signal. The difference, however, is that flangers use shorter delay times (typically 0.5–15 milliseconds).
Like chorus units, flangers apply an LFO to modulate the duplicated signal. Unlike chorusing, however, flanging modulates the delay time, rather than pitch.
The duplicated, modulated signal is then blended back with the original signal, producing a comb filter effect. The sound of a flanger is often compared to the sound of a jet plane taking off.
Flangers also use positive feedback to increase the intensity of the effect.
Flanging was originally created by playing an identical track on two synchronized tape machines, then lightly pressing down on the flange on the first machine. Doing this momentarily slowed down the machine, rendering it out of sync with the second machine.
The process was then repeated on the second machine. This would resynchronize it with the first machine.
The result was the characteristic, jet-like swooshing we now associate with the flanger.
Like chorus effects, there are countless different flangers with a zillion different designs, features, and controls. Regardless of which flanger you choose, most include at least some of the following controls:
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Rate controls the modulation speed.
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Depth controls the amount of delay.
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Manual controls the center frequency of the effect.
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Regeneration controls the intensity of the effect using positive feedback.
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Mix controls how much dry signal is mixed with the flanger effect.
Thanks to its shorter delay times, flangers produce a more pronounced sound than a chorus. Flangers are a great way to achieve Beatles-esque vocal effects and add a Corgan-like psychedelic vibe to your guitar solos.
You can also use a flanger to create metallic, sci-fi effects by cranking up its regeneration settings.
If you want to add vintage-tinged, Abbey Road-style filtering effects to your tracks, a flanger will deliver the goods.
Phaser: Produce Classic Sweeping Sounds
Like choruses and flangers, phasers double your signal. But rather than modulating the pitch or time of your signal, they employ a series of all-pass filters to shift the duplicate signal's phase, then mix the signal back together.
This results in a sequence of out-of-phase notches, which produces a pronounced sweeping effect.
Phasers rose to prominence in the 1970s and were frequently used by the guitarists of that era. That said, phasers were — and still are — also employed as a creative studio tool.
Of the countless phasers available, most include at least some combination of the following controls:
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Rate controls how often the center frequencies of the notch filters are shifted up and down.
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Depth controls how deep the notch filters cut.
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Regeneration controls the intensity of the effect using positive feedback.
Placing a phaser in front of a distorted guitar amplifier or amp simulation is the secret to achieving Eddie Van Halen's "Ain't Talkin' 'Bout Love" tone. Strapping a phaser across your drum bus will yield interesting textures a la Led Zeppelin's "Kashmir."
Phasers are also great for adding excitement to electric pianos and other keyboard instruments.
Vintage hardware phasers were deployed all over Daft Punk's Discovery album to give it its characteristic sound.
Conclusion
Modulation effects are kind of like dessert. Dessert may not be an essential part of your meal, but it makes the meal yummier and more enjoyable.
You can add dimension to your synth pads and clean guitars with a chorus, create psychedelic-tinged vocals with a flanger, or lend movement to dull-sounding keyboard instruments with a phaser. In short, if your mixes are sounding dull or lifeless, a few well-placed modulation effects are guaranteed to spice them up.
Whether you house them in your studio rack, on your pedalboard, or in your plug-in folder, modulation effects are a must-have studio tool for every engineer, producer, and musician.
