Wednesday, May 11, 2011

Building a sound: Modulation parameters

So after you've set up your wave and filter, and changed your amplitude envelopes, where do you go? There's still loads of complexity to put in your sound! Synthesizers generally have tons of modulation parameters. Here's a short list of some modulation elements:

Velocity: How hard the key is pressed
Keyboard/ Key Number: What number key you're playing (low C versus high C)
Aftertouch: Literally pressing down the key further after you've touched it. Not as common as the other parameters
Breath controller: Ability to hook up your synthesizer to a microphone or talkbox and change the sound with your voice (Also not as common)
Expression pedal: A pedal used other than the sustain that can be pressed at varying levels
LFO: A low frequency oscillator. Low enough that it does not affect pitch. Usually, several waves (sine, triangle, square, sawtooth, reverse sawtooth) can be picked. Note that the 'sync' button with LFOs determines if the LFO restarts every time the key is pressed or continues from its last spot. Also, the frequency of the LFO can be changed
Envelope: Once again, a user can set the ADSR envelope to modulate a parameter
Mod wheel: The wheel to the left of the keyboard that doesn't return to the center after use (that's the pitch bend)

Note that all of these parameters can change their amount they affect the sound. For example, a small LFO affecting the pitch can be used like a vibrato; this can also be used more heavily to create a siren-like sound.

These sources can be used to modulate almost any parameter on the keyboard. For example, a triangle or sine wave LFO modulating the pitch can give the vibrato affect on a string sound. Another good example is mapping velocity to cutoff. If the performer was using a rhodes-like sound, this could account for the harder presses sounding brighter, and the lighter presses sounding more dull, as a real rhodes does. Even more complex would be to map the key number to the decay and release of a piano sound. On pianos, the higher keys have a shorter release and decay, so this modulation set would make the sound more realistic. Of course, all mod parameters don't have to make sounds more realistic. They can be fun, or crazy, or downright weird. It's all up to you!

For a good read on some great patches, check out the Synthesizer Cookbook:

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