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Physics 1251
The Science and Technology
of Musical Sound
Unit 4
Session 37 MWF
Synthesizers
Physics 1251
Unit 4 Session 37
Synthesizers
In your own words, describe what a
synthesizer is and what it does.
A synthesizer:
• is an electronic device;
• is controlled by a player;
• produces electro-acoustic signals;
• simulates acoustic instruments;
• generates novel and unique sounds.
Physics 1251
Unit 4 Session 37
Synthesizers
1′ Lecture:
•
•
•
•
•
A Synthesizer is a player-controlled electronic device
creating electro-acoustical signals that emulate other
instruments or generate unique sounds.
Notes played by acoustic instruments pass through
four phases: (1) attack, (2) decay; (3) sustain;
(4) release. (ADSR)
Realistic synthesis requires sound to change with time
in pitch, frequency recipe, and amplitude during the
ADSR phases.
Synthesizers are either analog or digital.
Synthesizers employ either additive (or subtractive)
synthesis or frequency modulation (FM).
Physics 1251
Unit 4 Session 37
Synthesizers
80/20A
Synthesizer is a player-controlled
electronic device creating electroacoustical signals that emulate other
instruments or generate unique sounds.
What does that mean?
Physics 1251
Unit 4 Session 37
Synthesizers
80/20A
Synthesizer is a player-controlled
electronic device creating electroacoustical signals that emulate other
instruments or generate unique sounds.
Synthesizer
4
4
♩
♩
♩
♩
♩♩ ♩ ♩
Physics 1251
Unit 4 Session 37
Synthesizers
80/20A
Synthesizer is a player-controlled
electronic device creating electroacoustical signals that emulate other
instruments or generate unique sounds.
Synthesizer
Current I
Voltage V
I =V/R
Ohm’s Law: R =V/I
Physics 1251
Unit 4 Session 37
Synthesizers
80/20A
Synthesizer is a player-controlled
electronic device creating electroacoustical signals that emulate other
instruments or generate unique sounds.
Synthesizer
Current
+
+
-
-
+--
Voltage
+
Physics 1251
Unit 4 Session 37
Synthesizers
80/20A
Synthesizer is a player-controlled
electronic device creating electroacoustical signals that emulate other
instruments or generate unique sounds.
Synthesis or the Real Thing?
Physics 1251
♪
♪
Unit 4 Session 37
Synthesizers
The first modern synthesizer was
produced by RCA in 1955.
The Moog (rhymes with vogue)
synthesizer was invented in 1965 by
Robert Moog.
First Moog Synthesizer
Physics 1251
Unit 4 Session 37
Synthesizers
♪Realistic synthesis requires emulation of
realistic musical sounds.
80/20Musical
sounds are characterized by four
phases: (1) attack; (2) decay; (3) sustain;
(4) release; abbreviated ADSR.
Attack Decay
Sustain
Envelop
Release
Physics 1251
Unit 4 Session 37
Synthesizers
80/20Synthesizers
processing.
use analog or digital
Pressure
Analog
Voltage
Sound Waves
80/20Synthesizers
processing.
Digital:
Digital
Unit 4 Session 37
Synthesizers
use analog or digital
Pressure
Physics 1251
Sound Waves
80/20The
1000
0100
0010
0001
amplitude of the
waveform is digitized and
expressed as a binary
number.
Physics 1251
Unit 4 Session 37
Synthesizers
Digital to Analog Conversion (DAC)
1
2
4
8
0001
0010
0100
1000
DAC (Concept)
1010
0011
1101
Physics 1251
Unit 4 Session 37
Synthesizers
Electronic Digital-to-Analog Conversion
10
0
10
10
1
Input Number
Output Voltage
Physics 1251
Unit 4 Session 37
Synthesizers
Electronic Digital-to-Analog Conversion
10
0
10
10
1
Input Number
Output Voltage
Physics 1251
Unit 4 Session 37
Synthesizers
Electronic Digital-to-Analog Conversion
10
0
10
10
1
Input Number
Output Voltage
Physics 1251
Unit 4 Session 37
Synthesizers
Additive Synthesis:
•
The output signal is built up from a sum of
harmonic signals.
Σ
Physics 1251
Unit 4 Session 37
Synthesizers
Frequency Modulation (FM) Synthesis:
•
In FM Synthesis the frequency fo of the signal
is modulated up and down with a frequency f FM
. The vibration recipe contains peaks at
fo ∓ n fFM .
fo
fFM
If fFM = fo , then one produces a
harmonic series, f = m fo .
Voltage
Controlled
Oscillator (VCO)
Physics 1251
Summary:
•
•
•
•
•
Unit 4 Session 37
Synthesizers
A Synthesizer is a player-controlled electronic
device creating electro-acoustical signals that
emulate other instruments or generate unique
sounds.
Notes played by acoustic instruments pass through
four phases: (1) attack, (2) decay; (3) sustain;
(4) release. (ADSR)
Realistic synthesis requires sound to change with
time in pitch, frequency recipe, and amplitude during
the ADSR phases.
Synthesizers are either analog or digital.
Synthesizers employ either additive (or subtractive)
synthesis or frequency modulation (FM).