Synthesisers

• A Synthesizer is an electronic sound generating device, that creates sounds using oscillators and filters.

• An Oscillator provides the sound source. The next slide will show different waveforms that are commonly used.

Types of waveforms

• Sine• Square• Sawtooth• Triangle• Pulse• Pink noise• White noise

• Each waveform has it’s own unique characteristics, making them suitable for various sounds. For example, a sine wave has a hollow sound, making it an ideal starting point for clarinet and recorder sounds.

Exercise: Load up a synth in your DAW and try out the different waveforms in the oscillator section.Understanding waveforms - Video

Types of synthesis

• Subtractive synthesis – uses filters to subtract certain frequencies and thereby create the desired tone.

• Additive synthesis – Combines sine waves to create the desired tone.

• Physical modelling – Uses complex algorithms to replicate the physical characteristics of a real instrument.

• Sampling and synthesis – uses a small recording (sample) of a real instrument as its basis. Requires lots of computer memory.

Filters• In subtractive synthesis, different types of filters are used to

subtract harmonics from the waveform, thus changing the sound. (Sine waves are not used in subtractive synthesis since they do not have overtones. Therefore is anything was subtracted there would be no waveform, however additive synthesis uses multiple sine waves).

• Common types of filter used include, High pass, Low pass and Band pass filters. – High pass: removes frequencies below the cut off point– Low pass: removes frequencies above the cut off point– Band pass: allows you to choose a range of frequencies to cut or boost

Video - Filter types

Envelopes• An envelope refers to the dynamic shape of a sound. They

normally affect the VCA (Voltage controlled amplifier), but can be applied to the filters (VCF) or pitch (VCO). It typically has four parameters:

• Attack – how long a sound takes to reach its maximum level.• Decay – How quickly the sound decays from its maximum to its

sustain level.• Sustain – how long the sound continues at it’s level with your

finger still on the keyboard.• Release – how long the sound takes to decay to silence once the

key is released.Envelopes explained - Video

• LFO – refers to a Low frequency Oscillator. Although inaudible it ‘modulates’ the sound thus creating a vibrato effect.

• LFO’s generally work at 0-20Hz and are therefore below the range of human hearing. An LFO can be used to modulate different aspects of a synthesiser, such as the filters and envelopes. However it is commonly used to create a vibrato effect when applied to an oscillator. More information and a demonstration of an LFO can be found in the video link below.

Exercise – Try varying the LFO setting on a synth preset within your DAW. Listen to the effect.

LFO's explained - Video

History: Precursors to the Synth

• 1906 – Telharmonium. This was a 200 ton instrument driven by 12 steam-powered electro magnetic generators.

Short explanation of the Telharmonium - Video

• 1920 – The Theremin. This was named after the Russian inventor Leon Theremin. It had no keyboard to trigger the sound and the player would have to wave their hands between two antennae to create disturbances in an electrostatic field. It was used to good effect in the 1945 Hitchcock film Spellbound scored by Miklos Rozsa and produced a eerie ghostly sound.

Leon Theremin Playing the Theremin - Video

• 1928 – The Ondes Martenot, invented by Maurice Martenot. It had a keyboard with a pull out drawer that had a device to control the articulation (similar to todays pitch and modulation wheels). It was used by several French Classical composers including Messian in his Turangalila symphony. More recent example include the score to Lawrence of Arabia in 1962, and Ghostbusters in 1984.

Ondes Martenot explained – VideoDemonstration of the Ondes Martenot by Thomas Bloch

• 1931 – The Rhythmicon (also known as the Polyrhythmophone) is an early example of a drum machine and was developed by Leon Theremin and composer Henry Cowells, who wanted to perform composition with complex rhythms impossible for on person to play by themselves. It had a 17 note keyboard which when pressed generated pulses at a certain pitch. The 17 note allowed for the insertion of rests. Complex patterns could be created but it sound nothing like todays drums machines.

Rhythmicon demonstration - Video

• The earliest synths were ‘Modular’. In other words your bought them in sections and connected them with cables.

• The first portable synth was the ‘Minimoog’ made available in 1969.

http://www.youtube.com/watch?v=0z0cbMkOvY0Dr Bob Moog demonstrates the Minimoog

• Drawbacks or analogue synths include: poor tuning stability and lack of polyphony.

• In the 1980s’ FM (Frequency modulation) synthesis arrived. This used ‘additive’ synthesis which combined sine waves rather than filtering them. The most famous FM synth was probably ‘Yamaha’s DX7’.

http://www.youtube.com/watch?v=_7Qrn-6JyGUFrancis Monkman demonstrates Yamaha DX7 In 1987 Roland produced the ‘D -50’ which uses Sample & Synthesis.http://www.youtube.com/watch?v=u5fU63mf0QM Roland D-50 demonstration

• The most recent developments involve ‘Physical Modelling’ in which sounds are created in a virtual software world through complex mathematical algorithms. The simulation of a clarinet for example, would involve simulating the vibration of the reed, the resonance of the clarinet body and the effect of the flared end of the clarinet.

• Exam question:250 words16 marks

Explain the different components that make up a synthesiser and how they interact.

Identify the pros and cons of analogue, digital and software synthesisers.