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10 Things Everyone Should Know About Modulation Effects

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Read Time: 16 min

Effects in mixing are like the cherry on top of an ice cream. That little thing that makes everything so much better. We use effects to enhance our mixes and instruments, giving them more interest, depth and sparkle. Effects can make the most bland instrumental part sound vivid and cool. Whether it's tremolo to add rhythm to stagnant chords, vibrato for movement of your electric piano or chorus for you backing vocals, the creative use of effects can really help make a mix better.

In the following tutorial I'm going to go into detail of what each effect does, illustrate it with some famous examples from music history and provide you with practical examples that you can use in your mixes.

A note before I begin. I am a guitarist first and foremost and have grown up with all sorts of effect pedals, fooling around with all these wonderful sounds they can create. So many of my examples might be a bit on the guitar side, although I will also give you quite a few examples using other instruments. It's my hope that you understand the effect and what it does and at the same time sparks an idea that you could use, whether that's for your guitar part, vocal track or synth sound.

1. A Little About the LFO

The LFO, or Low Frequency Oscillator is what controls most of these modulation effects. An LFO functions at the frequencies from 0-20Hz, or below the threshold of human hearing. Therefore we don't hear what the LFO sounds like. But depending on what its function is we can hear how this LFO modulates our signal, creating all of these effects. Sometimes the LFO is controlling volume, creating tremolo, or sometimes its controlling frequency, creating a flanging or chorusing effect. Whatever the case is, it's usually this LFO that creates our effects, and depending on how it's used we get different effects. Electronic musicians and synth players are probably well acquainted with the uses of the LFO since it is the most important factor in any synth. It is where we decide on how we will modulate and change our default signal. If you want an in-depth look and introduction on how to use your synthesizers, check out Mo Volans's guide to Subtractive Synthesis here.

2. Delay Time

Since all of these effects are based around the LFO, what makes them stand out and be separated from each other is the delay time in which the LFO functions. Phasers have the fastest delay time of only a few milliseconds, while flangers have a delay time that's just a little slower, or around 5-15 milliseconds. Chorus on the other hand borders the boundaries of being a delay since it has the slowest delay time, its maximum being around 30-35 milliseconds. A combination of these separate delay times, coupled with the function of the LFO is what creates these effects.

3. Chorus for Depth

Chorus is a very popular effect and one that many guitarist have in their bag of tricks. From the eighties chorus solo to Kurt Cobain's grunge riffs, it's been widely used by six stringers everywhere. But in mixing it has way more uses than you might think. It can come in handy on any instrument, adding depth and a little stereo to your signal. What chorus does is it copies your signal and delays in reproducing it for about 15-30 milliseconds. It then splits the signal and can reproduce your mono signal in both the left and right channel, creating a chorused stereo patch out of your mono signal.

The chorus effect has the longest delay of all the modulation effects, and is commonly used for doubling vocals. Artificial double tracking is easy to do with chorus since it encompasses both a stereo creating delay and a slight pitch modulation with its depth and rate control. The rate control determines the frequency of the LFO while the depth control controls the amplitude. Chorus, like many other effects can be abused to create a detuned mess out of the signal. Too much rate results in an overload of the LFO with the frequency interfering with the original signal, sometimes causing it to sound detuned.

4. Chorus for Acoustic Guitar

A strummy acoustic guitar part is a perfect instrument to show how you can create more depth and interest in texture by using the chorus effect. This simple acoustic part has a much richer sound after having applied this chorus effect to it.

The chorus effect comes on after a few bars:

I'm using Logic's built-in chorus effect, but you can use whatever you have on hand. Even if you just have chorus pedals lying around you can use them to great effect. The chorus effect in Logic is pretty basic, and it doesn't allow you to change the delay time at all. It only has the simple depth(intensity) and rate controls found on most chorus pedals, along with the obligatory mix slider. I'm inserting this chorus effect as a send instead of inserting it on the track itself. That allows me to mix both wet and dry signals separately. If you are unfamiliar with using send effects, check out Joel's tutorial on how to set up send and return effects here.

Even just a low rate and medium intensity or depth is going to add subtle changes to you signal. When you are using send effects, be careful not to overwhelm the original signal with too much of the chorused effect.

Chorus can be used for a variety of instruments in your audio production. Whether you are using it for vocals, guitar or keyboards you can achieve a different result by just tweaking the parameters and experimenting. If you want to experiment with varying the delay times and are using Logic, you can choose to use Logic's Tape Delay plug-in instead. The Tape Delay plugin allows you to change the delay times and has a modulation section where you set the desired depth and rate you want.

5. A Wave of Flange

Flanging is very similar to chorus except for a few things that make it stand out. The delay time of a flanger is shorter, or from around 5-15 milliseconds, and it doesn't split the signal reproducing it in stereo, but rather feeds the signal back onto the original source sound. Lastly, it includes a feedback controls which allows you to feed the signal back onto itself, causing more phase cancellations. The reason flanging sounds so different is the fact that it is delayed and reproduced onto itself again, causing these phase cancellations. This causes a “comb filtering” effect where some frequencies some frequencies get canceled while others get stronger.

Flanging is a great effect on picked guitar as well as for that distinctive Beatles vocal sound. It is often considered to be invented at Abbey Road Studios during the Beatles' recording sessions. Another famous use of distinctive flanging vocal effect is the vocal sound of the 70s, where many singers had a distinct flange in some of their vocal tracks. Guitar-wise, Billy Corgan is a great example of heavily flanged guitar-solos. His guitar-solos throughout Siamese Dream are filled with heavy flanging, resulting in that unnatural solo sound that was so cool at the time.

At 3:11 Mr Corgan busts out with his signature flanged distorted solo sounds. Just by adding a tiny bit of flanger to such a distorted guitar sound creates a whole new beast out of your guitar sound. The thick fuzz of Corgan's Big Muff coupled with this slow but deep flange is what creates his thick and penetrating lead sound.

Like chorus, if you don't have a separate flanger plug-in you can create it with Logic's tape delay, or delay plug-ins that allow you to set delay times as low as 5-10 milliseconds. By using the depth, rate and intensity controls you can create chorus type effects, but when you throw a little feedback into the mix you get an effect more like the flanger.

A short while ago I wrote about how to create a smooth flanger and vibrato effect to add interest to your chord work. By subtle layering of the flanger and vibrato we get a completely different guitar sound. Check out how you can create a jagged little flanger effect here!

6. Flanger for Post Production and Sound Design

Flanger has other purposes not related to making your guitar sound cool. I've used it in sound design and post-production when I've needed to metalize certain sounds, or create weird sci-fi effects out of found sounds. Normally, by using a high rate and depth creates a really metallic sound that's perfect for weird sci-fi and machinery sounds. Listen to this sound bite that with some extreme flanging can create a cool sound effect. If you are doing any sound for picture or post production work, this simple effect can go a long way.

If you don't have any foley sounds to create sound effects out of and you don't have any powerful synths to design sounds in, you can use normal piano chords to make really weird sound effects with a flanger. Listen to this normal electric keyboard progression that is totally unrecognizable due to its heavy processing. Like something out of the Twilight Zone.

7. Phasers

Phasers are similar to flangers, and often mentioned synonymously. When people talk about flange, they are often referring to tracks that sound out of phase. When you are flanging an instrument, what you are essentially doing is putting it out of phase with itself, an effect that creates a flangy and/or phasy effect. Phasers work with a smaller delay time than flangers and have the shortest delay times of the aforementioned modulation effects. Phasers split the incoming signal in two, leaving one intact while modulating the second one with two constantly moving LFOs which create peaks and troughs in the signal, causing this familiar phasing effect.

Since the frequency modulation is irregular due to the LFO filter constantly moving over the frequency spectrum it sounds more unnatural to flanging which has a more regular nature to its phase cancellation. Although flanging can get pretty crazy and unnatural, you can always hear the rising and falling of the phaser working.

Van Halen is one of the most famous guitar players to utilize the phase effect. He has even had the MXR Phase 90 phaser effect designed for him by MXR. Notice the distinct phasing effect in the last notes of the riff from Ain't Talkin' Bout Love. Other guitar players famous for using the phaser is Brian May, who has a very typical phasing effect on his guitar riff on Keep Yourself Alive.

According to Wikipedia, the song Kashmir by Led Zeppelin was recorded with an Eventide Instant Phaser on John Bonham's drum track. I never paid much attention to it until I listened to it again. When I listened back to I was amazed of the high level of phase was dominant in the drum track. Although it sounds semi subtle, i.e. very slow it is incredible noticeable when you pay attention to it. To the layman, adding phase to a drum track sounds like a horrible idea and a rule that shouldn't be broken. But seeing that Kashmir is one of the greatest rock and roll songs of all time, that must say a lot about the ease of which us audio enthusiasts are willing to throw the rule book out the window.

Here is a small riff that utilizes some heavy phase. It was actually recorded with a Line 6 MM4 modulation effect with a slow double phaser with the a high depth rating. Notice how the riff kind of flies over the sonic spectrum. That's the phase effect swooshing around.

Phasers are a fairly complicated effect. The rise and fall of the swooshing sound is generated by two independent LFOs that are constantly moving therefore generating these rises and falls in different frequencies at different times. By experimenting with your phaser plug-in, like the one below that's found in Logic, you can tweak and modify the depth and speed of the rises and falls. You can modify the rate of the two LFOs separately, adding a higher level of customization to your phasing.

8. Vibrato

The vibrato is slow and subtle pitch-shifting effect. Just like a violin player or guitar player create a vibrato effect on their notes with subtle bending, the vibrato effect does the exact same thing on the signal in its entirety. Vibrato can be found in many songs, but it most notably used for creating that shimmer on a Rhodes electric piano or a Hammond organ. Its subtle effect is a great way to enhance an already great signal without over-modulating the signal and cluttering up the mix.

By using vibrato we can create nice jangly guitar lines. This was an effect my British room-mate was very fond of, because it reminded him of the Stone Roses and other assorted jangly English bands.

Here is an example where there are two guitar tracks playing different triads of the same chords, essentially harmonizing each other. Listen to how bland it sounds without any effects, although very harmonically pleasing. But it just comes alive when we apply some vibrato to it.

No certain plug-in is required to apply this effect. Just whatever vibrato effect or plug-in you have at hand. Note that you can go overboard in adding vibrato, just like any other modulating effect. Too much vibrato causes a jarring pitch effect that sounds out of tune. So if you have fast chords changes you might not want to use vibrato. It will probably do more harm than good. A low bluesy track with a Hammond organ filling up space in the background with a slight vibrato making it sound so much smoother is the prefect place to add some vibrato. A hard rocking punk track? Maybe not as much.

9. The Tremolo Effect

Tremolos are a great way to cause movement and interesting textures in your sounds. Like many of the other effects here, it is widely used by guitarists. In the tremolo effect, the LFO controls the variation in volume and frequency. With less frequency the volume rises and falls more slowly, causing a slower tremolo effect. Alternatively, with a higher rate control we can get a machine gun like staccato, that sounds metal-like.

Here is an example of a tremolo effect used to add an extra edge to otherwise boring guitar chords. By adding tremolo on top we instantly get a completely different sound. This guitar sounds like it's straight out of a film noir movie now!

I'm actually using the tremolo effect that's built into Logic's amp simulator, but you can use any tremolo effect. I recreated the same effect with Logic's tremolo plug-in, which you can also see below.

This tremolo is just a simple synced tremolo to 16th notes dotted with a really high depth rating.

The tremolo plug-in has a bit more to it than the simple effect of Logic's amp simulator, so you can play with the parameters and see if you can make subtle changes for more interest. You can make the tremolo effects smoother and symmetrical as well as choosing how much of a phase difference the tremolo effect will have compared to the original signal. Tremolo effects are interesting for slow sounds, like pads or chord strums. Just like vibrato, it doesn't lend itself greatly to fast songs. Due to its volume modulation it would just cause dissonant and uncomfortable sounds. But sometimes you might be going for that, who knows.

10. A Sense of Excitement

Now, effects can be used in a variety of ways. Sometimes you need to create an interesting sounding track so it stands out or just plain sounds better. But sometimes you just want an effect to pop in and out, adding excitement and a sense of change to your mix. When modulation effects don't constitute as a defining factor in the sound of a specific instrument, like the overdriven phase guitar above, you can use automation for an interesting effect. Like Van Halen's Ain't Talking 'Bout Love, Eddie only turns on his phaser pedal in the last notes of the riff, making them stand out even more. You can do the same thing by using these modulation effects to add accents to vocal phrases, or guitar lines. By having them pop in and out of a track you are constantly stimulating the listener with new and interesting sounds, that are tied to the already interesting instruments in your mix.


Effects are a great way to make your mixes more interesting. If you are a guitar player looking for something extra to your sound, try getting to grips with your guitar effects or buying some exotic new ones. If you are a mixing engineer struggling to keep your mixes fresh, try playing around with the assorted modulation effects that you have in your computer recording program. Maybe that phaser is just what that distorted guitar riff needs in the chorus. Those backing vocals can use some subtle chorus to keep them big but not overwhelming. Maybe you can add some interesting tape flange to a part of your vocal track. All these modulation effects are constantly finding new uses, subtle and extreme. If you are in need of creating some interesting synth sounds, try to add some modulation effects like chorusing and phasing to get a different and fresh sound to your synths.

Also, try layering these effects. Subtle flanging on vocals coupled with a little chorus can create a completely different vocal sound. Adding some vibrato on your tremolo guitar part can enhance an already cool guitar track. By using your synths multiple LFOs you can try and mix and match modulation effects in order to create a whole new synth sound. It can all de done with some subtle layering and some creativity

You shouldn't be afraid of experimenting or slamming some extreme modulation on a track if you want it to sound different. Don't limit yourself to compression, EQ, delay and reverb. The subtle delays found in these modulation effects are sometimes more relevant to what you hear in your head than going the traditional route. And with subtle processing you don't run the risk of cluttering up your mix with long delays and reverb trails. Instead, you will end up with interesting, tight and freshly effected tracks that work perfectly together. Or you might end up with a jumbled mess, but you don't know until you've tried all your options. By using, experimenting and understanding these effects you can easily add more tips and tricks to your mixing engineers tool-belt.

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