Audio Sound Distortion

Everyone who has ever listened a rock and roll or pop song, knows for sure that distorted guitars are great. Almost everyone that has ever used a DAW or even a console, kinda knows that when meters hit red, chances are that, something is wrong. Well, nothing of the above is necessarily true, and today, we’re gonna look at sound distortion: the good, the bad and the ugly, so, lets check it out!

What is Distortion?

I’m gonna try to give you a simple explanation about this, imagine a sine wave, now, imagine we make its amplitude bigger, and bigger, and bigger, until there’s no more room for more amplitude, but we keep cranking it, so, our sine wave starts to loose its sine shape, and if we keep boosting, it will start to look like a square wave.

We know for a fact that sine waves have no harmonic content, just fundamental tone, but, we also know square waves have lots and lots of harmonic content, both odd an even, so, when the sine waves starts loosing it shape, harmonic content start appearing. This, happens with every single waveform that you can imagine.

When you drive the input more than what the output can handle, you are in fact, distorting the sound, or, to say it in another way, you are exciting some of its harmonics, making them more noticeable, or you are creating new harmonic content. This, can be good, bad, nice, ugly, warm, harsh, or whatever adjective you wanna use.

The good.

For many years, guitar players have used distortion as something good, from amps to pedals, from tubes to transistors, and even digital algorithms, they have tried everything. Tastes change, and for example, in the 90s, many guitar players used to have some sort of digital distortion pedal in their rigs, today, that sounds kinda cheesy, while 60s and early 70s tube amps are probably the most sought after this days.

Of course not only guitarists take advantage of distortion process. Every single piece of studio equipment distort in some way. There’s no major studio in the world that hasn’t got at least one Neve 1073 kind preamp. Why? Because its distortion is highly musical, its transistors and transformers excite some harmonics that just makes anything sound nicer and warmer. Some vintage compressors like the LA-2A, or the Fairchild 660, are often used not to compress, but, to take advantage of how they distort. Units like the Avalon VT-747 or the Culture Vulture Thermionic, are modern classics in studios, and often used in the master buss, just to run everything to their tubes and get some warm distortion. In the last few years, lots of tape machine emulations appeared in the plugin world, and one of the benefits of tape machines is that they excite the 3rd harmonic, which makes the sound really warm.

Even distortion pedals (or software emulation) are used on daily basis in almost every studio, and not just for guitars. Snare drums sound great through a ProCo Rat. Synths like the Tb-303 are often used with the Ibanez Tube-scream pedal.

Speaking of synths, many new analog mono-synths have some kind of feedback distortion circuit, where the output is fed back to the filter to make it distort. Some other units might even distort with the mixer volume, just before feeding the filter. For example, the affordable Arturia MicroBrute, when you dial the output volume of any waveform past the 12 o’clock position, it will distort the filter!

On the other hand, most digital synths (software or hardware) have bit-crusher, which is a digital distortion method that crushes sample rate and bit depth, very much used in modern genres like Dubstep.

The bad.

As with everything, less is more. If you distort any signal a lot, it looses transients, and might loose every bit of emotion it had. For example, if you distort a vocal track a lot, you will probably not understand a word of it. Some distortions, like feedback type, might get out of control and become totally unpredictable (not in a good way). Lastly, when you excite harmonics too much, you probably won’t be able to tell the difference between a kick drum and a flute, so, yes, it looses its tonal qualities too.

The ugly.

Probably, the ugliest, most unpleasant distortion comes from the digital world. You can check this in a pretty simple way, just open any mix session in your DAW, and push track faders up, until master fader meter hits red. Yeah, not very musical, right? You can of course turn your master fader down, until meter doesn’t hit red, but you will get exactly the same results… why? The problem here is that what is distorting is the summing engine inside your DAW, so, the only way to avoid this distortion is to pull your track faders down, and never have any buss fader lower than the faders of the track feeding it. This, of course applies to analog consoles too, but, remember, analog distortion is warmer and sometimes is what you’re looking for.

Another ugly distortion is the one you get on your A/D converter when incoming signal is too hot. This ain’t musical, and you should try to avoid it.

Bottom line.

Tube distortion is great for basses, kick drums, rock vocals, guitars, electric pianos, hammond organs and master busses. Tape distortion is very nice for guitars, percussion, drum kits, vocals, keyboards and master busses. Guitar pedals, are great for snare drums, horns, keyboards, synths, and of course guitars. Transistor based distortions, might sound great just on anything, specially those from high end preamps or analog consoles. Just make sure you use them with caution, and if you are on a tight budget, well, there are lots of plugin emulation options around. You just need to try them!

[author image=”” ]Rafael Hofstadter is a recording and mixing engineer and sound designer with 10+ years experience in playing and programming synths, recording, mixing and producing pop/rock/folk albums. He also runs[/author]

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