Transcript Chapter5Presentation

Chapter 5: Electronic Music and
Synthesizers
Who uses electronic musical synthesizers?
Each advance in electronic technology is followed by a
concomitant advance in synthesizers and new
developments in the expressive range of electronic
music.
Chapter Outline:
1. Combination of waves
2. Analog synthesizer
3. Digital synthesizer
Combination of waves and
Modulation
Methods of combining waves:
1. Simple addition (Superposition)
2. Gating
3. Amplitude modulation
4. Balanced modulation
5. Frequency modulation
6. Pulse-width modulation
Gating
Amplitude Modulation (AM)
100% Modulation and
Overmodulation
Balanced Modulation
Frequency Modulation (FM)
Radio Waves
FM vs AM: What's the difference?
AM: The amplitude of the
signal is varied to incorporate
the sound information.
Frequencies are in kHz.
FM: The frequency of the
carrier signal is varied to
incorporate the sound
information. Frequencies are
in MHz.
FM vs AM
Advantages and Disadvantages
FM signals are not affected by static.
With an FM broadcast, slight changes in amplitude
don't matter -- since the audio signal is conveyed
through changes in frequency, the FM receiver can
just ignore changes in amplitude.
AM carrier waves have much longer wavelengths than
FM carrier waves, and as a result, they can bend
around obstacles like mountains and buildings better
than FM waves and can travel greater distances before
the signal fades.
Pulse-width Modulation (PWM)
Analog Synthesizer
Signals
Two types of signals are used in a synthesizer:
audio signals and control signals.
Audio signals: electronic signals with frequencies in
the audible range and amplitudes of about 1.5 V,
which can be input to a speaker.
Control signals, oscillatory or constant in voltage,
amplitudes up to about 5 V, used to control the
operation of various components in the synthesizer.
Keyboard
Provides two functions:
Gives the control signal that determines the pitch
Provides the starting signal that triggers the envelope generator.
Sample and Hold
In general, a keyboard pitch-control signal is input to the oscillator,
and the audio output from the oscillator is sent to a speaker.
Pressing a key will then cause the production of a tone with the
pitch associated with that key.
The oscillator remembers the pitch and continues to sound at this
pitch even when the key is released, which is known as Sample
and Hold.
The tone will then continue at the same pitch until another key is
pressed, at which time the oscillator will remember the new pitch.
Voltage-controlled oscillator (VCO)
Voltage-Controlled Amplifier (VCA)
Envelope Generator
Block diagram with envelope
generator