Types of Synthesizers and How They Work By: Steven Baker

Outline What is a synthesizer? History of synthesizers Waveforms and Harmonics Components of synthesizers Different types of synthesis

What is a Synthesizer? Creates vibrations like any instrument Modular Creates vibrations like any instrument Vibrations in the form of an electrical signal Signal able to be modified and manipulated in ways that are not possible with acoustic instruments Modular vs. All-In-One All-In-One

History of Synthesizers RCA Mark II History of Synthesizers RCA Mark II Sound Synthesizer (1957) First programmable sound synthesizer Moog Synthesizer (1964) First commercially available modern synthesizer Much more compact due to development of integrated circuits Yamaha GS-1 (1981) First digital FM (frequency modulation) synthesizer Software Synthesizers (1990’s – today) Moog Synthesizer Massive (softsynth)

Analog vs. Digital Analog synthesizers use analog circuitry to generate a signal Digital synthesizers use digital signal processing (DSP) to generate a signal Digital synths typically offer more features at a given price Certain types of synthesis are only feasible with digital

Waveforms Synthesizers use alternating current to create their electrical signal The way this current changes overtime can be represented as a waveform The shape of the waveform determines what the signal actually sounds like (timbre) Shapes of waveforms can be simple, complex, or even completely random

Examples of Waveforms Sine Wave (440Hz) Sawtooth Wave (440Hz) Triangle Wave (440Hz) Amplitude Frequency (440Hz and 880Hz)

Harmonics Sine Wave (100Hz) The reason sound waves sound different is because they have different harmonic content Harmonic Multiple of a fundamental (original) frequency Example: 100Hz note 2nd harmonic = 200Hz 3rd harmonic = 300Hz Etc. Sawtooth Wave (100Hz) Triangle Wave (100Hz)

Components of a Synthesizer Hardware components for a basic analog synthesizer Voltage-controlled Oscillator Generates original waveform that is then manipulated by other components Voltage-controlled Filter Help shape a sound by filtering out unwanted frequencies Essential to subtractive synthesis Voltage-controlled Amplifier Boosts the electronic signal before it is sent to be played from a speaker Envelope Generators Help shape the sound further

Subtractive Synthesis Triangle Wave (100Hz) Before Low-Pass Filter Primarily used by older, analog synthesizers Start with waveform then subtract away until desired sound is achieved Use of filters to subtract away High-Pass Low-Pass Band-Pass Band-Reject (Notch) Cutoff Frequency Triangle Wave (100Hz) After Low-Pass Filter

Additive Synthesis Based on the idea that any sound can be made by combining a series of sine waves at various frequencies Typically digital Not feasible with analog Most sounds in nature are complex 100’s if not 1000’s of sine waves to be accurately reproduced Not limited to just sine waves Any types of waves can be mixed to create new, interesting sounds Three sine waves (100Hz 300Hz and 500Hz)

FM Synthesis Frequency Modulation Two Waves Sine wave (440Hz) Frequency Modulation Two Waves Carrier (actually heard) Modulator (controls pitch of carrier) Usually only implemented in digital synthesizers Example: Yamaha GS-1 880Hz 220Hz Result of carrier modulated over time

Conclusion What a synthesizer is History of synthesizers Waveforms and Harmonics Components of synthesizers Different methods of synthesis

References http://synthesizeracademy.com http://www.aes.org/aeshc/docs/jaes.obit/JAES_V35_9_PG741.pdf http://en.wikipedia.org/wiki/Synthesizer