Types of Synthesizers and How They Work By

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? 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

RCA Mark II History of Synthesizers �RCA Mark II Sound Synthesizer (1957) � First programmable sound synthesizer �Moog Synthesizer (1964) Moog Synthesizer � 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) 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 (440 Hz) �Sawtooth Wave (440 Hz) �Triangle Wave (440 Hz) �Amplitude � Frequency (440 Hz and 880 Hz)

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

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 �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-Reject (Notch) �Cutoff Frequency Triangle Wave (100 Hz) Before Low-Pass Filter Triangle Wave (100 Hz) 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 (100 Hz 300 Hz and 500 Hz)

FM Synthesis �Frequency Modulation �Two Waves �Carrier (actually heard) �Modulator (controls pitch of carrier) �Usually only implemented in digital synthesizers �Example: Yamaha GS-1 Sine wave (440 Hz) 880 Hz 220 Hz 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_V 35_9_P G 741. pdf �http: //en. wikipedia. org/wiki/Synthesizer