Modulation Effects Explained

Modulation Effects Explained

Every musical composer and sound producer knows how it works or at least heard of modulation effects these days. Modulation effects change the feature of the sound by producing a sense of movement, depth, and dimension. Depending on which parameter of the waveform you are trying to modulate, you will have a different effect in the end, such as tremolo, vibrato, phaser, or flanger effects.

What are the modulation effects?

Before we introduce you to our modulation effects list, let’s dive in for a second into what modulation actually is. Depending on the knowledge field, the term ‘modulation’ has different meanings. For example, in music theory, modulation means changing the main key of the composition. But in electronics and telecommunications, this term has a very different meaning. But since we are not very interested in applied physics, modulation is a process of changing sounds in music production.

Usually, modulation happens through controlling the carrier signal with the source signal, which in this particular case is called a modulator. Although some modulation effects involve delaying the signal, echos and reverbs are usually not classified as modulation effects. Those are called time-based effects despite that you actually can achieve some modulation using delays and reverbs.

It is interesting to know that for some reason, distortion and overdrive are also not classified as modulation effects, and it is very strange since using distortion, you are actually modifying the signal by adding harmonics to the frequencies. So you might wonder what modulation effects are? Since music production’s evolution doesn’t slow down, there are lots of effects on the market. And the best modulation effects examples would be chorus, flanger, phase shifter, tremolo, vibrato, and Haas effect.


A chorus effect can be achieved in music production by combining two or more sounds with a slight delay and a little different pitch. Since the differences are usually extremely small, those concurred sounds are perceived as one without any impression that something out of tune. Depending on the settings, the chorus can give you either a rich sound with shivering movements or a threatening and aggressive pulsation.

There are some situations when chorus can occur naturally. Have you ever wondered why you can’t achieve the sound of the orchestra by multiplying one solo violin part? That is because a string orchestra has a natural chorus effect that gives it sound a sense of space and grandeur. If you have four violinists that perform the same part, there would be some time and pitch variations in their playing.

The same goes for the actual choirs since “chorus” actually means choir from Latin. There are some solo instruments that can produce this effect naturally. For example, a slightly out-of-tune honky-tonk piano or twelve-string acoustic guitar. There are a lot of digital chorus plugins, but usually, those effects are used in the form of guitar pedals and rarely as the rack mounts. Two of the most famous chorus guitar pedals would be Boss CE1, released in 1976, and Electro-Harmonix Small Clone, which was used on “Come As You Are” by Nirvana.


Flanging is an audio effect that is created by a flanger. This audio effect is acquired by taking two corresponding signals and delaying one of them for a few milliseconds. Occasionally the phase of the delayed signal can be reverted, which results in another alteration of the effect. The secret of the real analog flanging is the phased variation of the speed of the delays. With the blistering development of digital technology, digital flanger plugins can combine convenience with analog vibes quite well.

There are a lot of arguments about who actually is the ‘author’ of the flanger. Les Paul is said to have discovered the effect somewhere between 1940 and 1950, though all of his experiments were with acetate disks on variable-speed record players. The first song that has a distinctive flanging effect is “The Big Hurt” (1959) by Toni Fisher.

The experiments with flanging didn’t stop there, Ken Townsend, an engineer at EMI’s Abbey Road Studio, invented the artificial double tracking, as the answer to John Lennon’s request to get the sound of double-tracking, later specifically John Lennon called the ADT technique “flanging.” The first Beatles track that involves flanging was “Tomorrow Never Knows” from Revolver, recorded on 6 April 1966.

Phase shifter

The phase shifter is very similar to the flanger, except for there is no delay used. The phasing effect is achieved by dividing the audio signal into two parts. The first part is left untouched, and the second one is treated by the all-pass filter, and the phase is reverted. When signals are combined, certain frequencies will be out-of-phase, which means that they will cancel each other out.

The phase shifter’s most distinguishable characteristic is that the out-of-phase frequencies would be spaced unevenly, thus creating a sentence of movement. When you think of phase shifter, imagine 80’s hard rock. Amongst others, Eddie Van Hallen was a very prominent user of phasers. His famous instrumental “Eruption” features one of the most notorious stompbox guitar pedal phasers – MXR Phase 90.


The tremolo effect may seem very similar to the flanger, but in fact, it very much is not. Tremolo can be characterized by a very sudden and rapid change in the amplitude of the sound. Although this effect could be easily achieved mechanically on every string instrument except for the grand piano, and there is a variety of ways how to achieve it using electronic means.

It is very hard to say when the first electronic tremolo was made, but the first experiments dated back to 1941. In the 50’s, some manufacturers started to put this effect into guitar amplifiers. One of the most prominent examples of that era would be Fender VibroLux. The first experiments with electronic tremolos were partly mechanical and used electrolytic fluids. Later examples included tubes that were modulated by turning off and on. This effect was highly popularized in the mid-60’s by surf musicians.


There is a common misconception that vibrato and tremolo are one and the same thing. Partly it is because these effects indeed sound very similar, but in fact, Leo Fender is the one to blame for this confusion. When he installed a certain device on his Stratocasters, he mistakenly called it a tremolo arm, despite that it actually is a vibrato arm. To this day, guitarists all around the world still call this device a tremolo arm.

So what is the actual difference between the tremolo and vibrato? Well, if tremolo is to simply put it the rapid repetition of the same note, the vibrato is the slight variation of the pitch on the note.

If you are a guitar player, you can achieve a tremolo effect by rapidly plucking one string with your pick. You can make the vibrato on the guitar by holding one note on the fretboard with your left hand and slightly moving your finger up and down. But the other reason for the confusion is that it is very hard to achieve vibrato on the other instruments without changing the amplitude of the sound. For example, vocalists can’t achieve vibrato without tremolo.

Haas effect

In 1951, Helmut Haas discovered the Haas effect, which is a binaural psychoacoustic phenomenon. The main idea of the effect is the perception of the sound by the human ear. Despite being a very precise system, sometimes certain things still can trick the hearing system. The Haas effect does this trick, as it creates the echo of the sound by shifting the second sound just for a few milliseconds. As a result, we have space and airy sound, which genuinely consists of two sounds, not one.

You can apply the Haas effect in various ways depending on which tools you have. You can apply a stereo delay plugin on your mono track, which is the simplest way to do it, but this method involves a lot of manual labor, so be prepared for it. The stereo delay plugin has to have isolated precise controls for the delay of each channel. But if your delay controls are interpreted as note durations, it wouldn’t be possible to apply the Haas effect. Another way to achieve the Haas effect is to copy and paste the mono source track and apply a delay plugin.


To conclude all said above, you should always think about what does your mix need. Would applying these modulation effects on your mix make it beneficial? Chorus, flanger, phase shifter, tremolo, vibrato, and Haas effects will add different things to your audio material, but still, it will certainly enhance it beautifully and make it truly distinguishable.