The Ultimate & Definitive Guide to Distortion

Griffin Brown
December 31st, 2019

The Good, The Bad, and the Nasty

Distortion, when unwanted, is the bane of the producer or engineer. It can destroy the way something sounds, and mask other elements by distracting the listener or introducing conflicting frequencies. When used intentionally, however, it can be a useful tool to give your mix some extra life.

In this article, I’ll be touching on what exactly distortion is, as well as its positive and negative effects on a mix. We’ll discuss sources of unwanted distortion and their solutions, and ways to use distortion to your advantage (in drums, basses, vocals, and instruments) without ruining your mix.

Be sure to grab “The Distortion Elimination Checklist” below, a step-by-step guide to locate and remove unwanted distortion in your project.

What is distortion?

Before discussing how to get rid of distortion or when it can help, it’s important to understand what it is in the first place. Distortion is a disturbance in a signal’s waveform, which can be caused by several processes.

In an audio setting, this usually occurs when the signal is set to go louder than it’s able to do. In an analog setting, this limit is determined by the circuitry of equipment used, and in a digital setting it’s determined by software.

Essentially, there is a ceiling for how loud an audio signal can go. A system, analog or digital, is built to expect signal below a certain level. In most DAWs like Ableton, Logic, and Pro Tools this level is 0dB. For the sake of this article, we’ll refer to that level as the “threshold of distortion”, or TOD.

Sometimes, a signal exceeds this level. Because the system can’t accurately capture or play this back, it compresses the parts of the signal that cross the threshold of distortion down to this level. This can be done gently or harshly, depending on the system and settings at play.

Above is a diagram showing theoretically how distortion works. This concept is applicable in both an analog and digital setting. The vertical axis is the amplitude of the signal (which we perceive as the volume or loudness). The horizontal axis is time.

On the left, you see the first cycle of an undistorted sound wave (a sine wave, the simplest waveform), resonating in positive and negative cycles (going above and below 0 amplitude). This wave will act as our signal here. Note that this concept will apply to all signals, not just sine waves.

As the wave’s amplitude increases, its peaks approach the dotted lines, which represent the threshold of distortion. Once the peaks cross the dotted lines, the system is unable to recreate this part of the signal. So, the system compresses the peaks that have passed the TOD, lowering the wave’s once-curved arcs to straight lines along those dotted lines. The last waveform (what’s green) would be output by the system.

As you can see, the waveform has been changed, and rather harshly in this scenario. This is called “clipping”, and is an extreme form of distortion usually found in digital systems.

Do you notice what this change has done to the shape of the sine wave? The waveform looks a lot more like a square wave now. This is important in understanding what distortion is doing to a signal and why you may or may not want it to occur.

A square wave contains more harmonics than a sine wave. Harmonics are higher frequencies based off a signal’s main, root frequency (called the fundamental frequency). You can see a comparison of a sine wave’s harmonics (just one, the fundamental frequency) and the many harmonics of a square wave in the “frequency domain” graphs found in the diagrams below (think of the graphs on the right simply as EQs).

Note: I have not indicated frequency or amplitude for either of these waves, or for their harmonics. As long as they’re on the same note, the relationship between a sine and square wave at any frequency or amplitude will be like this.

Essentially, when a signal has lots of harmonics, it has more content in high frequencies, and sounds brighter than a signal with less harmonics. Think about how a square wave sounds brighter than a sine wave, even if the two are playing the same note.

The sine and square waves in the time domain graphs above are at the same frequency (or playing the same note), but the square wave has more harmonics. You can also see this represented on an EQ. Try it out yourself with your favorite synth!

This is done easily with NI Massive. Use the “Sin-Square” wavetable in any oscillator. With the Wt-position (wavetable position) knob set all the way to the left, Massive will output a sine wave. With it set to the right, Massive will output a square wave.

Anywhere in the middle morphs between the two. Insert a MIDI clip and draw in a note on the piano roll. Insert an EQ or any spectrum analyzer on the channel, and move the Wt-position knob in Massive as the note plays. Notice that there is more high frequency content in the square wave, even though the same note is being played.

With this knowledge, we can say that distortion adds harmonics to a signal, and thus higher frequency content. This can have negative or positive impacts on your mix, depending on where and when distortion occurs or is used. The key is understanding why you may want distortion in certain situations and not others.

SIDE NOTE: Analog and digital systems tend to distort differently and have different sonic qualities. Analog distortion can actually have a relatively pleasing sound due to the way the circuitry handles the overloaded signal, or the way magnetic recording tape saturates. Digital distortion, on the other hand, tends to sound harsh and brittle as the signal is handled in a more extreme manner. Unless otherwise specified, I’ll be talking mostly about digital distortion since most of you are probably working in software and not large analog consoles.

How to remove unwanted distortion

When starting out, every producer and mix engineer runs into unwanted distortion. You may find distortion occurring at a channel in your project, or at your master channel. Or you may hear distortion occurring but not know where it’s coming from. It’s happened to all of us. I find the best way to solve these kinds of problems is starting from the beginning of a signal’s path (or chain) and following it through to the end.

Distortion in the Recording/Audio Signal (and how to solve it)

Is the signal itself crossing the threshold of distortion? This can often happen in the case of recording vocals or an instrument. While distortion on these elements can be nice (we’ll get to that in a bit), it’s best to have a clean signal to work with and distort after recording. This gives you more control over the distortion, and will ultimately sound better and more professional.

On every audio interface that you’d use to record, there is an input gain knob, controlling the gain of what you’re recording. In the process of setting things up, you may have turned the gain up too high, increasing the signal’s amplitude past the TOD, and recording the signal into your DAW already distorting.

Unfortunately, the only solution here is to re-record. Simply turning down the volume or gain in the software won’t have any effect, since the signal distorted before it got to Ableton, Logic, Pro Tools, or any other DAW you’re using. The software simply recorded that distorted signal.

Below is a picture of a recorded guitar track in Ableton. As you can see, the guitarist played a bit too loud on one note around 0:02:25, and the audio distorted. In the next pictures, I zoomed in on the note in the Sample Editor to show how the peaks have been compressed, and are not as rounded as the rest of the recording.

You can see in the last picture that, even after reducing the gain, the distortion remains.

Pro tip: You can easily prevent this problem in the recording stage. Once you’re getting signal into your DAW, ask the performer to sing/play as loud as they plan to. While they do this (or after you do this yourself), check to see if the incoming signal is distorting. If so, turn the gain knob down on your interface and turn the gain up in your software (since this will be after the audio is captured). You won’t lose any volume and the signal will be recorded cleanly. It’s best to leave a bit of wiggle room after this too, as the performer may get caught up in the heat of recording and sing/play louder than they did before. Better to be safe and make sure that golden take doesn’t distort!

The original signal can distort in other circumstances as well. In the case of software instruments, most if not all of them have a master volume knob, and usually a meter showing the volume of your signal.

Below are some pictures of this knob and meter (in the red) on two common synths, Massive and Serum. Treat this knob the same as you would treat an input gain knob on an interface. If the synth is distorting, turn it down until the signal no longer distorts, and compensate at the channel fader to make for up the lost volume.

Distortion within the Processing Chain (and how to solve it)

Whether it’s a compressor, EQ, or any other processor, adding plugins to a signal can increase its volume. As a result, the signal may be louder after a plugin, and eventually distort if it crosses the threshold of distortion.

Even if a later plugin in the chain brings the volume down again, you are only decreasing the volume of an already distorted signal (just like in the previous example). This does not solve your problem, and the signal may still be distorting even if you don’t see the channel fader clipping.

I mostly work in Ableton Live, and monitor this issue with the help of the volume faders attached to each plugin. If you’re working in another DAW, just keep an eye on output meters in your plugins (most should have them).

In the below example, see how one of the plugin faders has gone into the red, but not the other? The signal crossed the TOD after this compressor, distorting in the process. Even though I have a utility plugin bringing the signal gain back down after it, the distortion has already occurred.

If you hear distortion and don’t see a sign of clipping on any of your mixer’s faders, make sure the signal isn’t distorting after any of your plugins. It may seem tedious and take a bit of time, but it’s worth it to get rid of that nasty distortion.

However, the best way to deal with this problem, again, is to make sure it doesn’t happen in the first place. While you’re working, check that the signal hasn’t distorted each time you add a processor to a channel. Thankfully, most processors have a built-in gain knob, which can be turned down to avoid signal exceeding the TOD.

Distortion at the Channel Fader (and how to solve it)

This one is pretty self-explanatory. If your signal exceeds 0dB on a channel fader, it may start to distort. If the signal isn’t distorting in the processing chain and your channel fader is set to something less than 0dB, you shouldn’t run into any issues. Problems may occur if the signal leaves the processing chain close to the TOD and the volume fader is set above 0dB.

In the example, the signal is leaving my processing chain at -1dB, and my channel fader is set to +2dB. As a result, the signal overall is hitting +1dB, and crossing the threshold of distortion.

To avoid distortion at the channel fader, first take care of the levels coming out of your plugins. Then simply watch your meters as you work and keep your signal out of the red.

Important: Technically, there are certain scenarios mentioned above that won’t result in any distortion, and have to do with something called “bit-depth”. Without getting too deep into the specifics of digital audio, some plugins and DAWs have a high bit-depth and do not distort at the expected level.

Ableton Live, for example has a high bit-depth. As a result, though the volume meters on plugins and channel faders may go into the red, distortion will not actually occur. In Ableton, this applies to the channel faders and the native plugins, but not the master fader, which can audibly distort when crossing 0dB. Certain third-party plugins, like Massive and Serum, also do not distort due to supporting a high bit-depth.

However, not all plugins or DAWs react this way. Some will distort, and in an analog setting the scenarios mentioned above will often result in distortion. So it’s better as a general habit to keep everything out of the red.

Distortion at the Master Fader (and solutions)

Distortion at the master fader follows the same ideas as distortion at channel faders. If the summed level of your channel faders exceeds the TOD at the master channel, the same distortion occurs.

If you find your master channel in the red, you can solve this by decreasing the level of all other channels by the same amount. To leave some wiggle room, I typically decrease by the amount clipping, plus a little bit (so decrease all channels by 5dB or so if signal is hitting +2dB on the master fader).

Highlight all channels apart from the master channel, and attenuate everything said amount. This will turn down the overall level going into the master channel while preserving the balance of the mix. Don’t just turn the master fader down, as it’s generally a good idea to keep it at 0dB so you can monitor for potential distortion without missing it.

Distortion from Compressors/Limiters

As I mentioned before, when signal crosses the TOD of a system it is compressed down to that level. Thus, distortion is really another form of compression.

See How to Mix Music (Part 2): Signal Flow & Plugins if you need a refresher on the parameters of a compressor:

The TOD is the compression threshold, and the ratio of this compression is essentially infinity:1 since signal is compressed so extremely. The attack would be 0 seconds, as the signal is compressed instantly. When looking at distortion this way, we can see that hard compression can cause similar destruction of the waveform. Be conscientious about your compression settings, as they may cause signals to distort.

For easy-to-follow steps to get rid of unwanted distortion, check out “The Distortion Elimination Checklist” below.

Intentional Distortion with Plugins

Now we get to the good stuff! How can we use distortion to our benefit? We now understand that distortion adds upper harmonics (or higher frequency content) to a signal. With this concept in mind, we can apply distortion in situations that would benefit from some upper harmonics.

Simple as that! However, the way we use distortion will slightly differ depending on what we distort and what we use to distort, so we’ll go into that now:

Our Favorite Distortion Plugins

The best way to perform intentional distortion is by using distortion plugins. These emulate the sound of distortion without the hassle of clipping channels or plugins.

Distortion plugins generally have two main parameters that do most of the work. There is usually some distortion type parameter, which determines the sonic timbre of the distortion. Each distortion plugin will have its own distortion types, which are subtly different from one another. It’s best to explore these plugins and find what sounds good to you.

Distortion plugins will also have a drive parameter, which determines how hard the signal is distorted. Think of the drive as determining how hard the signal is fed into the distortion. Higher drive will naturally distort the signal more.

Apart from these parameters, each plugin will have its own unique controls, which we’ll cover now:

iZotope Trash 2

A personal favorite of mine is iZotope Trash 2. In my opinion, it has really everything you’d need or want in a distortion plugin. It has dozens of different distortion curves, which range in sonic quality from soft and warm to harsh and abrasive. After choosing a curve, a drive value can be set, causing harder distortion the higher the drive is.

Trash also has some nice functions that are unique to it as a distortion plugin. For example, it contains two stages, so you are able to distort twice consecutively in one plugin. Each stage can use its own curve and drive settings.

Trash also has a multiband mode, which allows the separate distortion of different frequency ranges. Once again, separate curves and drive settings can be selected, now in each band.

This is nice for just distorting the highs to add some brightness to a sound, or just the mids to add some beef. I would advise against distorting lows however, as having a clear and defined low end is important in having a professional-sounding mix.

(Trash contains several non-distortion functions within it as well, feel free to check them out!)

FabFilter Saturn

FabFilter’s Saturn is another great option. It also offers multiband functionality like Trash, and has several distortion models to choose from. Saturn has the ability to split up into 6 separate bands, allowing for incredible amounts of control. Each band has adjustable drive and model (distortion type) settings, as well as their own EQ and a feedback function.

The most unique aspect of Saturn is its modulation section, in which you can add modulation sources like LFOs and envelopes to modulate any knob. Simply add a modulator with the [+] icon, click the crosshairs icon in the top-left of the source, and drag to any knob. This will modulate the chosen parameter with the modulation source, a very useful function to create quick and dynamic automation.

These are just a couple options out there, but most distortion plugins will at least have a drive function of sorts as well as a distortion type setting. If there are any plugins you like to use, feel free to comment them below so others can check them out!

How to use Distortion to Improve Your Sound

As mentioned before, we can use distortion for its ability to bring out and add high frequency content to a sound. Trust your ears! If you think something in your mix sounds a bit dull and would be improved with some added harmonics, slap on a distortion plugin.

Be mindful not to overdo it though, as distorting everything will add higher frequency content to all your elements, eventually making your mix too bright. But some distortion on certain elements can be very useful.

Some notes

Distortion is a versatile effect, but as they say, “you can’t polish a turd”. Ideally, you want to have the best starting material possible beforehand. Distortion can be really helpful, and can drastically improve the sound of an element in some cases. However, nothing beats starting with a well-designed synth or high-quality samples. Distortion can simply help take them from good to great.

Also keep in mind that you may generally want to EQ elements before and after distorting. An EQ before distortion will cause said distortion to only affect frequencies you allow through the EQ. An EQ after distortion will help clean up any negative effects caused in distorting, like mud in the mids or overly bright high frequencies.

For more discussion on EQing specific elements in a track, visit previous articles here, under the Audio Engineering section.

Lastly, remember that turning up the drive of any distortion plugin will increase the amplitude of the signal. Be sure to turn the output of your distortion plugin down so volume is consistent before and after distortion. Either use I/O meters in the plugin (Trash 2 has these on the right side) or toggle the plugin’s bypass on and off to check that this is achieved.

This way, you should be able to hear what the distortion is actually doing to the signal. As producers and engineers, we have the tendency to be seduced by an increase in loudness. Balancing the volume of your signal on both sides of the distortion will help you distort (or not) based on the sound of the distortion, rather than the increase in loudness. LOUDNESS ≠ FULLNESS

Distorting Drums

I put some level of distortion on drums in just about every project, specifically on the kick and snare. Since kicks have a good amount of low frequency content, distortion will add and increase some harmonics in the mids. This can be really nice for adding some thickness and warmth to your kick, allowing it to have some weight.

If I’m distorting a kick with iZotope Trash 2, I tend to avoid the multiband mode and distort equally across the whole frequency spectrum. I select my distortion type (I went with “Crunchy Grunge”) and increase the drive to taste. In this example I only set the drive to 2.3, which is subtle but noticeable. Note that I lowered the output level by 4.6 dB to compensate for the added level from the drive.

Distorting a snare can also help beef up the mids, as well as adding some brightness in the highs to help it cut through the mix. If the snare needs some thickening, general distortion can be done. If brightness is the goal, subtly distorting the highs can be helpful.

Here, I elected to just distort the highs. To do so, enable multiband mode, select the high band on the frequency spectrum above, adjust the range of the band, choose the distortion type, and adjust the drive to taste. For this example I went with the Tape Saturation curve, which emulates the effect of saturating magnetic tape used in analog systems.

This specific example was drastically affecting the sound of the snare, which I wanted to preserve. So I only set the drive to 1.0. Remember that distortion is technically destroying your waveform, so if your intentions are subtle then don’t overdo it. I also lowered the output 5.5 dB here, compensating for added level.

I would generally advise against distorting hats and percussion, as distortion is only going to add or enhance harmonics above what’s in the signal already. Thus, distorting these high-frequency rich sounds can cause things to become overly bright and brittle quickly.

Distorting Basses

Adding some distortion to a bass can be quite effective. On an 808 or other bass that contains primarily low frequency content, light to moderate distortion can have similar results to distorting a kick drum.

If I were distorting an 808, I may add some distortion specifically to the mids using the multiband mode. Select the middle band on the equalizer, adjust the range of the band, choose your distortion type (I used “Crunchy Grunge” again), and adjust the drive to taste.

Distorting Vocals

Distortion on vocals can also be nice. In this case, since vocals already have plenty of mid and high frequency content, distortion can be used to add some brightness and air. This can help the vocal cut through the mix (like we did with the snare), and can even help enhance the intelligibility of the vocal.

Overall distortion can be used, or light high-band distortion if you specifically want to enhance the highs. Note that I have lowered the output 2dB to compensate for the gain this distortion added.

Distorting Instruments & Synths

The application of distortion towards instruments and synths follows similar ideas as in vocals. If you want to bring out harmonics in the mids or highs, distort accordingly. If you’re using Trash or another distortion plugin that offers several distortion curves or models, feel free to explore and find the one that sounds right for what you need.

Distortion as an Effect

Distortion is also useable as an effect. Increasing the drive on a distortion plugin will distort the sound harder, eventually changing the timbre of the sound to something nastier. The classic distorted guitar is a great example of this. What was once a clean electric guitar becomes gritty and full of attitude.

You can add this effect to anything your heart desires: drums can become lo-fi and mangled, basses can become filthy, vocals can become blaring and aggressive, and instruments can take on a new life. Experiment with different distortion plugins, settings, and original material to find the sound that appeals to you.

But again, there can be such thing as too much distortion. Trust your ears and be confident in your decisions!

When used with intention, distortion is a fantastic asset to the producer or mix engineer. I hope you guys enjoyed the article, and wish you all luck in using distortion to inject some life into your own tracks and mixes. Later!