While we don't often think of modulation plugins when we think of essential tools for mixing, modulation plugins can be crucial parts of your audio effects toolkit.

The beauty of modulation plugins is their ability to add movement to give mixes more life and interest. While there are several types of modulation plugins out there, some of the most popular include chorus, phaser, flanger, and tremolo.

Though all modulation effects deliver different sonic qualities, each of them works by using a low-frequency oscillator (LFO) to modulate the signal. Whether the LFO is modulating volume, pitch, or timing depends on the effect.

Today, we're going to break down a few of the most popular types of modulation effects and provide you with our favorite modulation plugin options for each.

Let's get weird!

Chorus

Chorus is one of the simplest yet most popular forms of modulation. With a chorus modulation plugin, you make a copy of your original signal and double it with slight changes in pitch. When you blend these two signals together, you get a watery, shimmery, and detuned effect that can give even the smallest and thinnest of sounds dimension and depth.

When you vary the LFO parameters when using a chorus effect, you alter the sound. For example, if you increase the LFO frequency on a chorus effect, you get a faster rate . On the other hand, if you increase the amplitude of your chorus effect, you get more depth .

When most people think of a good or familiar chorus sound, they think of a warm, fluid sound with a classic tinge.

Let's check out some of the best chorus plugins on the market.

1. Eventide TriceraChorus

The TriceraChorus plugin from Eventide was inspired by the 70s and 80s stompbox-style choruses, giving you that classic BBD-style delay. In reality, the 80s was the golden era for the chorus effect, and it's most likely the sound you have in your head.

This plugin blends unique tri-chorusing qualities with a three-phase LFO and micro-pitch detuning, giving you wide, thick, and deep chorus sounds with total flexibility. We love how easy the GUI is to navigate, as you have 11 main controls for fine-tuning the sound of your chorus, including Depth, Tone, Pan, Amount, and Detune, among a few more.

You can pick between three modes, including Swirl, Ribbon, and Hotswitch, depending on the sound you're going for.

Swirl delivers a flanger-like sound, Ribbon utilizes the unique Eventide "blending" feature, and Hotswitch allows you to switch modulation settings in live performance mode.

Whether you're looking for that super lush, old-school chorus sound to a sci-fi-style, frenetic wobble, the TricerraChorus from Eventide is one of the best chorus plugins for modulation on the market.

2. PreSonus Analog Chorus

Analog Chorus from PreSonus is a 1-3-voice chorus processor with a stereo width control and an optional LFO delay time modulation. For Studio One users, Analog Chorus has been a staple plugin for many years. Thankfully, the company finally decided it was time to release its chorus plugin to the rest of the world.

We love the easy-to-use interface, which delivers no-nonsense controls and analog-style tones with a tinge of saturation. All of the warbles and wobbles you could want to recreate that familiar stompbox tone can be found in this plugin.

Plus, its simplicity makes it a good choice for beginners who don't want to spend time tweaking a hundred LFO generators to get the perfect tone.

While you won't find a modern algorithm or a laundry list of parameters in this chorus plugin, don't underestimate it. Remember, you don't always need the most complex plugin to get the space and depth that you're looking for.

3. TAL-Chorus LX

If you're looking for a free plugin to deliver that classic analog sound, we recommend checking out TAL-Chorus LX . This 1:1 standalone plugin is super easy-to-use and comes with a lush sound that is reminiscent of the chorus unit found on the old Roland Juno 60 synthesizers.

In terms of GUI and disk space, this free chorus effect is a pretty tiny little plugin. You get five simple parameters to mess around with, including two different chorus modes and three knobs for mix, volume, and stereo width. For a gentler chorus, go with MODE I. For a more intense chorus, go with MODE II.

TAL-Chorus LX provides a warm and familiar color and doesn't hit your CPU hard in the slightest. Of course, you might find the control options lacking compared to some of the paid chorus plugins above, though with a free price tag, it's hard to complain. Overall, it's an excellent plugin when you're looking to add that extra little bit of 'oomph' to your track.

Phaser

A phaser is a modulation effect that uses an LFO to manipulate the phase of a signal.

Now, you might be asking,

What in the world is phase?

Well, let's say you're looking at a graph with a sine wave on it. The phase of that sine wave is its starting position along the graph's X-axis.

To create a phaser effect, you must split the waveform or signal and pass it through a number of "all-pass" filters while altering the phase. You then combine those manipulated signals with the dry signal. If any of the frequencies are 180 degrees inverted or "out of phase" from the original sine wave, they cancel out.

This cancellation is where you get those characteristic phaser notches.

A phaser uses a sweeping LFO that moves through the frequency spectrum to create notches at different points. With every all-pass stage you add, you get more notches.

Let's check out some of the best phaser plugins on the market.

1. Soundtoys Phase Mistress

Soundtoys is one of my absolute favorite plugin developers. They have a fantastic lineup of effects plugins, from delays to saturators and beyond. One of my most often used plugins in the lineup is Phase Mistress.

This one-of-a-kind phaser plugin is an emulation of the old-school Electric Mistress chorus/flanger stompbox from Electo-Harmonix. Of course, looking at this plugin compared to the stompbox, it's easy to see that it's capable of far more.

You get so many classic tones to choose from, including that of the Mu-Tron Bi-Phase, the Boss Super Phaser, the MXL Phase 90, the Moogerfooger 12-Stage, and the Electro-Harmonix Small Stone Phaser.

One thing that sets this phaser plugin apart from others is its recognizable analog tone. You'll also find a wide range of parameters to manipulate your sound, including tempo-locking tools and rhythmic modulation.

While you can certainly build your foundation atop one of the 69 included presets, the real fun comes from tweaking. Start by setting different numbers of poles and stages from 2 to 24, and carefully listen to how each impacts your tone. Then, fine-tune the resonance to lock it in.

If you really want to get serious, you can draw in your own custom LFO or use numerous settings to set your control voltage.

Overall, if warm, fat analog tones are what you're after, Soundtoys Phase Mistress is one of the best phaser plugins on the market today.

2. Arturia Phase Bi-Tron

The Bi-Tron was first introduced as a stompbox unit many decades ago and became an instant hit, thanks to its warm and hypnotic tones. Even with a clear vintage look and tone, there's something about the Bi-Tron that makes it feel futuristic.

With two phaser circuits, every signal that comes out of the Bi-Tron has a doubled sound.

Most everything Arturia develops is top-notch. The company is known for its supreme analog hardware emulations, and the Bi-Tron modulation effect is a great example. You get dual 12-stage circuits, a manual control pedal, two sweep generators, and more!

While you could certainly spend hours tweaking the various parameters of this plugin, there are 37 beautifully crafted presets to get you started, delivering instant access to some of history's most iconic phaser tones.

3. Blue Cat's Phaser

The Blue Cat's Phaser plugin was modeled after a number of analog phaser circuits, giving you the sounds you're likely already familiar with from your favorite recordings. However, with a simple and streamlined GUI, you get the precision of a modern processor.

Blue Cat's Phaser is a wonderful free VST alternative to those listed above, delivering up to 32 phasing stages, sine/triangle LFO shapes, stereo spread control, and feedforward/feedback paths.

The stereo spread control sounds absolutely fantastic, giving you that deep and wide stereo phasing as well.

Flanger

Flanger was the original form of modulation. Many people say it sounds like an airplane taking off, which is a great way to distinguish it from its closely-related phaser cousin. The flanger effect was first derived back in the 1960s when engineers played dual tape machines with identical songs at the same time.

When one engineer applied pressure to the flange (the edge of the tape machine's reel), it would slow down and playback out of sync. When those two signals were then summed back together, you'd get a unique comb-filtering sound. This sound became a staple for 60's psychedelic artists.

In today's VST flangers, we use LFOs to modulate the delay time rather than physically slowing down a copy of the signal.

You'll often find "regen" and "feedback" controls on flangers, which can intensify the overall effect. We love using flangers to get stereo width and thickening, though they are just as great for creating that iconic jet engine sound we spoke about earlier.

1. Eventide Instant Flanger MK II

Besides the unmistakable TriceraChorus VST plugin, Eventide also happens to have one of the best flanger VST plugins on the market. The Eventide Instant Flanger MK II is an authentic emulation of the classic Eventide Instant Flanger rackmount that came out back in 1975.

The original rackmount was a truly magical piece of hardware, delivering double-tracking, stereo-widening, subtle modulation, and extreme flagging. Luckily, you don't have to shell out thousands of dollars for one, as the Eventide Instant Flanger MK II is now available in VST plugin form.

However, even as a plugin, you get all of the best analog characteristics of the original, as well as the uniquely emulated tape machine "bounce back" speed recovery.

Beyond the depth and feedback parameters, this plugin delivers a tantalizing pseudo-stereo mode, which allows you to configure your outputs in Deep, Wide, and Shallow modes.

For warm, old-school modulation, you can't go wrong with this killer modulation effect from Eventide.

2. ToneBoosters ReelBus 4

The ToneBoosters ReelBus 4 plugin is quite unique in that it not only delivers the sultry sound of a classic tape flanger, but also has an onboard magnetic tape recording modulator and a BBD echo delay.

ToneBoosters ReelBus 4 was made to deliver the glorified sound of analog tape from Hysteresis adjustments to Drive EQ to flanging to tape echo, you get a distinctive analog performance from this plugin. You can even use the tape hiss plugin to dial in the perfect amount of noise for a truly vintage tone.

The plugin makes classic tape flagging easy, thanks to the tempo-synced LFO. Best of all, you get all of this versatility at a surprisingly low price.

3. Blue Cat's Flanger

Similar to the Blue Cat's Phaser plugin found above, the Blue Cat's Flanger delivers the sweet, classic sounds of the 1970s and 1980s. The interface is simple and streamlined, making it easy to create unique flanger effects from any source you have. Whether you're looking for soft, warm flagging or an aggressive, metallic comb-filtering sound, Blue Cat's Flanger can do it all.

We love the Spread control, which allows you to turn stereo processing on or off and control the overall width of your flanger effect.

Beyond the regular parameters you'd expect from a flanger plugin, such as depth, delay, and rate, you'll also find the ability to toggle between various LFO shapes and choose between in and out-of-phase feedback and feedforward paths.

Best of all, this modulation VST plugin is completely free to use!

Tremolo

Tremolo is what we call an "amplitude modulation" effect, meaning it varies the signal volume over time. Tremolo is a pretty easy effect to get the hang of, as you can hear the LFOs' effect on your audio.

To get a gentle and vintage tremolo, you can use a soft, rounded sine wave shape. For a helicopter-like sound, you can use a steeper square wave.

If you're a guitarist, you're likely already familiar with tremolo, as it's often found on guitar amps. Country and surf music makes unabashed use of tremolo.

However, with that said, it's a great effect no matter what music you make and can be especially useful for breathing life into otherwise static sources.

1. Eventide Undulator

Eventide is back again with its unmistakable Undulator tremolo plugin, which was inspired by the iconic H30000 Ultra-Harmonizer effects processor hardware. This unique effect combines two detuned voices, two delays, and an AM/FM tremolo modulator. You can pull a wide range of stunning effects out of this modulation plugin.

Lock in your effect with sync functionality or tap tempo control, detune your delays to get a unique stereo spread or get real-tme dynamic control over your waveform with the Ribbon button.

Right now, 100% of the proceeds of this plugin go to charities that support the fight against systemic racism and violence. Be part of forward change while creating out-of-this-world music.

2. Soundtoys Tremolator

No list of great tremolo plugins is complete without mentioning Soundtoys Tremolator . This effect emulates just about any classic hardware tremolo effect you could think of, including a Wurlitzer electric piano tremolo and Fender Vibrolux tremolo.

You get a breadth of dynamic control for speed, depth, and more. The MIDI sync makes it easy to lock your effect in time with your music, while the Rhythm Editor allows you to program an infinite number of rhythmic patterns, perfect for sequencer-style or auto-gated tremolo effects.

In essence, you get modern control with vintage sound quality. You can use the custom LFO waveshape editor to craft the perfect waveshape for your mix or choose from Tremolator's large list of standard LFO waveshape.

The plugin delivers supreme control and s great for just about any kind of program material.

3. Goodhertz Trem Control

Goodhertz is a software developer based out of Los Angeles that manufactures some of the coolest-looking plugins on the market for Mac and Windows users. The colorful and modern designs make them easy on the eyes too.

The Goodhertz Trem Control is one of the most powerful tremolo plugins on the market, giving you everything from classic tremolo emulations to futuristic effects. W love the intuitive layout of the plugin, which gives you access to Shape, Rate, and Vibe controls, as well as Advanced Rate, Advanced Shape, and Trim modules.

Whether you need modern rhythmic gating or vintage-inspired tremolo wobbles, Goodhertz Trem Control is capable of it all. You'll find plenty of awesome presets to pick from, giving you a good starting foundation.

Elevate Your Mix with Modulation

When applied properly in a mix, modulation effects can offer some of the most exciting ways to create new tones and transform your audio. Whether you're looking to add dimension, depth, movement, or interest to your mix, let some of the fun features on these plugins guide you.