Chorus
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[edit] Chorus
[edit] General
This is a device that simulated natural effects that take place in our every-day life. What it does it preatty simple but the resultes can be spectacular and highly destructive.
This effect can be heard when:
- You stand at a street and hear the Doppler effect of a motor when a car passes by and it mixes with a reverb or an echo of the same motor coming from an opposite direction (can be heard really well early in the morning as one and one car passes by in places that have a tendency to reverb or echo).
- You hit a note in a piano, causing other notes to vibrate at certain frequencies.
- Detune two square waves.
[edit] What it does
In an effect machine, the machine takes a sample of the sound that is being processed through it and delays it (phase-delay, or a slight time delay), pitch-shifts and/or adds more feedback (number of sources in this case?), all dependent of what it is set to do. Signals mix linearly, that is, if I add two identical square waves, the resultes will be a square wave that is double in amplitude, that is a signal mixing at a 0°phase (or 360°), but if I'd mix them together at a 180° phase I would get a flat line, if the pitch gets higher then the space between rising and falling edges becomes shorter, etc:
Here is a pic to see it grafically, the fluctuations on the positive edges of the unprocessed square waves are the resultes of additive synthesis of a square wave, using Fourier series expansion.
The chorus can be totally random and it can be totally predictable. Here is a collection of waveforms that I got out of tweeking a chorus that is processing a square wave, I automated a chorus to various settings at a speed that is not pleasant to listen at, but it gives great comparison on the waveforms that come to light.
Just to give a litle idea of how it operates..
Here is the file I got those images from: Square wave on chorus
