---Unit+4

Granular Synthesis Thingy

Synthesis Notes

Idiot's Guide for Test

VCO - Voltage Control Oscillator VCF ADSR LFO VCA Low pass Filter Frequency modulation Mod Wheel After Touch

__**Basic Tools For Understanding Synthesis**__

Synthesizer - A musical instrument that produces waveforms, typically in the audio range of about 20-20,000 Hertz., electronically

VCO - Voltage Control Oscillator - creates the sound

VCF - Voltage Control Filter - rounds the waveform, creates the timbre, essentially plays with the overtones of each sound

VCA - Voltage Control Amplifier - amplifies sound to requested sound level

LFO - Low Frequency Oscillator - modifies sound by attaching another oscillator to your sound at any point listed above

ADSR - Attack Decay Sustain Release - called envelopes, shapes the filtering and the aplifying

Synthesizers broken up into two categories:

"Analog" and "Digital"

Analog: Keyboard 2 oscillators (at least) An LFO 2 envelope generators A Filter VCA

When a key is pressed, a pitch control signal is sent to the oscillators (VCO)

First Pathway - oscillator generates desired frequency, wave form then routes an audio signal to the Voltage Control Filter, waveforms then created

Second Pathway - keyboard has also sent control signals to another part of the synthesier, the envelope generator Two envelopes, one controls filter, the other controls the amplifier

Trigger sends message to to generator telling key has been pressed, opens and closes gates

Gate tells generators that the note is still being played

Filtering:

A device that eliminated some frequencies from a sound spectrum, can increase level of other frequencies High-pass (high frequencies) Low-pass (low frequencies) band pass (series combination of low and high pass) Notch (series combination of low and high pass) or a combination

Modulation - changes character of sound by throwing something at it to change it

VCF - cutoff frequency (and perhaps Q) controlled by amount of input voltage

Let one device change the sound of another device, LFO can add vibrato effect

Ring Modulater - takes two signals and produces either the sum or difference of the two signals

Frequency Modulation - a change in the pitch of a signal, low modulation sounds like vibrato or some type of trill, depending on shape of wave form, when modulation wave is in audible range perceived as change in tone color

Mod Wheel - controller used to control amount of modulation, set to left side of keyboard, used to add vibrato

Q - a certain range of frequencies

After Touch - type of control data generated by pressing down on one or more keys on a synthesizer keyboard after they have reached and are resting on the keys