Distortion

por Rafa

Hi! This is Rafa Monteiro, from Montpellier, France. This is an assignment for lesson for week 4 of “Introduction To Music Production” at Coursera.org. Today, I would like to talk to you about a subject that I, being a guitarist, love: distortion!

Distortion can be either a curse or a blessing (usually it’s the former). A distorted record or mix can be spoiled beyond fixing, meaning that not only it will sound very bad, but the work will have to be done from scratch. On top of being very frustrating, it is also time and energy consuming – and if you happen to be renting equipments or even a studio, can be very expensive too.

What is distortion?

Putting it in a simple way, distortion is a change in the timbre and loudness of the sound due to changes in the electric or digital signal when their gain is pushed over the limits of operation of your gear.

Every piece of equipment, from the microphone to the DAWs and reference monitors, are constructed to operate with a determinate level of signal without changing the sound*. Within those limits, the signal will be recorded and won’t be distorted.

The problem arises when we raise the level of the signal beyond the threshold of the gear.

That’s what happens when the signal is raised above the threshold.

 

The signal will be cut above the threshold point (clipped) and more partials will be added to the signal. This will change the timbre of the sound and increase the sensation of perceived loudness (even with the signal maxed out at the clipping point).

Again: once the wave hits distortion, it can’t be fixed by artificial means.

Avoiding distortion

We can have distortion in two procedures: during the recording and while editing and mixing stuff.

To avoid recording distortion, we must set the preamp gain in a way that allows the musicians to play freely and also let us to record with a high gain without hitting the red line, always paying attention to the LEDs and graphic indicators. Hitting that sweet spot can be very tricky, and it’s not uncommon to record the same piece of music a couple of times just to adjust the gain levels.

Once we record, we avoid distortion by paying attention to the manipulation of the recorded signal, never raising it above the 0 dB FS. FS is for Full Scale, and it’s the threshold for the digital signal in a DAW.

Putting it simple: do not cross the red line. Green is low, yellow is good, and red is bad.

How to use distortion in a good way

Distortion, however, can be a powerful tool for expression.

The distorted sound usually is brighter, heavier and louder than it’s natural counterpart. On top of that, the distorted sound can be manipulated and equalized, generating different timbres. In fact, there are many devices projected specifically to create specific distorted sonorities.

Each device produces a different kind of distortion

Distortion can be used in a creative and expressive way. In fact, many musicians (mostly guitarists) do this all the time, recording instruments with their sound pushed beyond the threshold of distortion.

Check out when Eric Johnson turns on his Tube Screamer distortion at 1:35 to create a contrast between “clean” and distorted sounds.

The Foo Fighters record their guitars with a lot of distortion, always in a creative and musical way.

Distortion is a powerful tool for expression, that should never be left unchecked or used without control or purpose.

*In fact, all equipments affect the recorded sound. Since there aren’t perfect electronic components, everything can (and will) change the recorded sound into something slightly different. Usually, the alteration is almost imperceptive, unless you are using a poor piece of gear. Also, the less the equipment interferes with the sound (which means higher fidelity of sound), the more expensive it gets.

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