Understanding Effects: Distortion

I notice a lot of guitar players tend to be, through no fault of their own, groping in the dark when it comes to using effects pedals. I find that a big problem is that manuals only delve into quick-and-easy type settings that doesn’t explain much about what is actually happening to the sound. I’m going to try and demystify some of this so that you can learn how to get the exact sound you are going for.

To begin the series, I’d like to talk about a fundamental guitar effect, that’s become so ubiquitous that it comes built in to most amplifiers: distortion.

We all know the sound – a screaming guitar solo or a thunderous riff are products of distortion that have become the hallmark of the rock guitar sound. So what is happening to the sound that causes this change? To put it simply, it does exactly what it’s named – it “distorts” the actual sound waves that are coming from you guitar. Imagine a sine wave with its nice flowing curves when it’s visualized. Distortion occurs when this signal is boosted past the limit of the maximum volume. The wave literally hits a ceiling, visually chopping off the top/bottom curve to produce a flat part in the wave. This is what we hear as distortion. Different types of distortion are available, but they are generally categorized as saturation/overdrive (mildly distorted) and distortion (greatly distorted sound). When these deformities in the sound waves happen, they also create harmonics/overtones that we perceive as adding a richness to the sound.

The controls that we have over this effect are generally: level/volume, and the amount of distortion (sometimes there’s a bit of EQ as well). It’s easy to hear the difference each of those controls make, but there are some traps that you will want to watch out for. Distortion is a dynamics based effect, meaning it affects our perception of volume. If you’re switching between a clean and distorted sound, it’s important that the volume level transitions smoothly. This is more difficult than it sounds, because if a distorted signal and a clean signal were to have the same amount of energy, the distorted sound will be perceived as being louder. Secondly, when you’re using heavily distorted guitars against the drums, there can be a lot of overlapping high frequencies between the cymbals (and crowd noise, if you’re in a venue) and guitar sound. You can avoid this by using and equalizer to get the guitar to sit in an less occupied part of the frequency spectrum. Many distortion stomp boxes will have a built in tone control to deal with this issue.

Overdrive is a type of distortion that is often associated with driving the power amp to distort. This is distinct from (heavy) distortion which is done in the pre-amp stage. Power amp distortion is generally described as a “crunch” tone. Historically, this is how all early forms of distortion were achieved, before amps came with the effect built-in. That means if you want a vintage blues/rock type of sound, you should go for this type of distortion by cranking that tube amp up.

Now for a few tips and tricks. When it comes to distortion, I want to emphasize that less is more. Even heavily distorted genres like metal can benefit from this mindset. Dynamic range is lost as more distortion is used and eventually you will end up with little difference between the loud and soft parts of your playing. If we were to take this idea (less is more) to the extreme, we get to the territory of saturation. This is a type of distortion that is most often associated with analogue gear that is powered by tubes. By using an almost imperceptible amount of distortion that retains most of the original sound, you’re able to add a subtle layer of overtones to the signal.

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