Course:PHYS341/2018/Calendar/Lecture 31

Phys341 Lecture 27: Summary and web references

2018.03.26

Textbook Ch.24

1. Electronic instruments
   • Standard musical instrument plus electric “assist” (not true “electrophones”):
   • Straightforward amplification
   • Also, electrically driven pumps for organ pipes, vanes in vibraphone etc.
   • Electrophones:
   • Electro-mechanical: tone wheels.
   • Electronic oscillators: all-electronic using valves, later transistors and integrated circuits.
   • Digital: computer-generated waveforms, output to speakers by digital-analog conversion (DAC).
2. Electric organs
   • The first electric organs, starting with the Telharmonium and later with the early Hammond Organs (1929), used a tone wheel to generate a sinusoidal electrical signal.
   • The rotating iron wheel made a sinusoidal disturbance in the current flowing through the adjacent electromagnet, which could be amplified and heard via a speaker.
3. Electronic oscillator
   • Harmonic (linear) oscillator produces a sinusoidal output with one frequency component.
   • Simplest electronic form has:
   • An inductor (coil of wire) – behaves as a mass.
   • A capacitor (two plates separated by a tiny gap) – behaves as a spring.
   • Like a mass on a spring, this circuit produces an output at its resonant frequency.
   • Amplified using valves, transistors, integrated circuits (as the 20th century progressed).
   • Basis of all electronic instruments using real physical electronics.
   • (NB Computers generate sine waves mathematically).
4. Theremin (1928) https://en.wikipedia.org/wiki/Theremin
5. Ondes martenot (1928) https://en.wikipedia.org/wiki/Ondes_Martenot
6. Musique concrète
   • Music made from recorded sounds – anything (as opposed to pure electronic music)
   • https://en.wikipedia.org/wiki/Musique_concr%C3%A8te
   • Developed by Pierre Schaeffer, beginning in the early 1940s.
   • Possibly the most famous piece of musique concrète was composed in 1963 by Ron Grainer and realized (i.e. did all the sound recording and tape-splicing) by Delia Derbyshire. https://en.wikipedia.org/wiki/Delia_Derbyshire
7. Moog synthesizer https://en.wikipedia.org/wiki/Moog_synthesizer
   • Modular synthesizer
   • Interconnected electronic modules that serve different functions. Basic examples:
   • Voltage-controlled oscillators (VCO, define frequency).
     • Generates simple waveforms (sine, square, sawtooth etc.).
   • Mixer
     • Adds different waveforms.
   • Low-frequency oscillator (input to VCOs).
     • Controls vibrato etc.
   • Envelope generator.
     • Controls attack, sustain, decay.
   • Sequencer
     • Produces sequences of voltages
   • Wendy Carlos et al. https://en.wikipedia.org/wiki/Switched-On_Bach