I will write about three kinds of distortion.
- Analog distortion
- Digital distortion
- Intentional distortion
I want to kick this off by saying that distortion is nothing natural, it is manmade, and I believe it to be unintentional at first, but then put to use to sound signals to create a distinct sound. What distortion is, is simply put, a sound wave, that is naturally curved, but cut off and flattened in the tops. A sound signal that is captured and hits the limits of the technology used to capture it when the signal wants to go a little further, but the components have already hit its maximum limit. Which is the perfect cue to the first topic:
With analog distortion I mean every distortion that is not specifically digital, which I will cover below. Analog distortion can occur as a physical limitation in microphones, headphones or speakers, but also as an electrical limitation in one or more components in the electrical chain that the sound signal passes.
Physical distortion appears when the sound or electrical signal wants to push the membrane further than physically possible. In a microphone this happens when the sound, typically a transient (a strong peak of energy in the sound) pushes the membrane of the mic to its maximum capacity, either inward or outward, and wants to keep pushing it. Like a rubber band, you can only stretch it so far before it snaps. The membrane of the microphone does not snap, but is not physically able to move further. This caused a “flat” top on the electrical signal as the membrane cannot provide any further electrical signal than its maximum. This is when recording the sound signal. When playing it back, the same physical limitations can appear in headphones or loud speakers. The electrical signal wanting to move the element past its physical limitation. The difference between the two states (recording or playing back) is that when the distortion happens when recording, it cannot be undone. When it appears when being played back, all you have to do is lower the volume (decrease the electrical signal) and the distortion will go away.
The same goes for electrical distortion, but instead of a physical limitation it is a limitation on what voltage the electrical signal can be, passing through various components along its path. Various components produce different kinds of distortion, like a tube, which provides a warm kind of distortion which is often desirable (when looking for distortion). Again, here is a difference if it happens when recording or when playing it back. Taking a typical path from a microphone, through a mixer, into a recording device, there are some steps where the signal might get distorted.
- In the input gain of the channel where you connect the mic.
- On the fade that controls the mic.
- The output of the mixer.
- The input (gain/level) on the recording device.
Now, it would be safe to assume that keeping the signal as low as possible on all these points would be wise to avoid distortion. And it is a correct assumption, but of course there is a ‘but’. That ‘but’ being the electric S/N ratio (Signal to noise ratio) of the components. All electric components have a kind of background noise that you cannot avoid, so you want to separate your desired signal as much as possible from this noise, keeping it as strong and loud as possible, of course without triggering distortion.
As where analog distortion (where ever it may appear) can add a certain character to the sound, the digital distortion, however, does not. As where analog distortion may be wanted, the digital distortion is always unwanted (when recording or creating music). What it does is it clips the sound, which becomes very unpleasant to listen to when it comes out through the headphones or speakers. The phenomenan occurs when the audio signal (that is assigned a digital value) reaches the highest available value, and cannot get any higher. As when the analog signal is distorted it is still “soft around the edge” whereas the digital is absolute and sharp.
Last, but certainly not least, intentional distortion. As I have mentioned a few times above, distortion may not always be a bad thing, it can add character to the sound signal when used right. (And not only on screaming rock guitars!) The distortion can be used on everything, and there are a lot of FX that emulates distortion in various ways, if you work in a DAW (Digital Audio Workstation – or Sequencer as some people say). It is also widely implemented in various synths, weather hardware synth or software synth. (It is called “drive” sometimes!). If you have trouble getting a sound to “cut through” the other elements in your mix, distortion may be one way to get it to “pop out” of the mix, without necessary boosting the volume of it.
As always! Stay playful, creative and curious!