Physics 1251 The Science and Technology of Musical Sound

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Physics 1251The Science and Technology of
Musical Sound

• Unit 4
• Session 38 MWF
• Analog Recording and Playback

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Physics 1251 Unit 4 Session 38 Analog
Recording

• Who is Robert Moog and why is he important?

Robert Moog (rhymes with vogue) invented the
Moog Synthesizer, a pioneering instrument in the
development of the synthesizer.
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 1' Lecture
• Recording requires a transducer, such as a
  microphone, to produce an electrical signal.
• Common types of microphones are (1) condenser
  (2) magnetic (3) dynamic (4) ribbon (5)
  piezoelectric (6) carbon.
• Recording also requires amplification as well as
  a storage medium.
• Analog recording media include vinyl record,
  magnetic tape, magnetic disk and optical film.
• Playback uses physical principles in which
  mechanical oscillations, magnetic domains and
  optical density variations produce electrical
  signals that are analogous to the recorded sound.

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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20An electric guitar uses a magnetic pickup
  that produces an electrical signal by a
  time-varying magnetic field.

Steel Guitar String
Pickup
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20The Faraday Effect a magnetic field that
  varies in time produces a voltage and current in
  a coil.

Current
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20A Condenser Microphone uses electric
  induction to produce an electrical signal.

Charge V (eo S/x)
Voltage V
Current I
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20Magnetic Microphone a small magnet,
  attached to a moving diaphragm induces a voltage
  and current in a coil.

Current I
Voltage V
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20Dynamic Microphone a diaphragm moves a
  small coil in a magnetic field inducing a voltage
  and current.

N
S
N
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20A Ribbon Microphone uses a light weight
  ribbon of metal moving in a magnetic field to
  produce electrical signals.

N
S
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20Piezoelectric Microphone a thin crystal is
  bent which produces a small voltage.

Voltage V
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20Carbon Microphone a diaphragm compresses a
  sealed container of carbon granules, changing its
  resistance.

Current I
I V/R
Voltage V
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Microphones
• ElectrostaticInduction
• Condenser
• MagneticFaraday Effect
• Magnetic
• Dynamic
• Ribbon
• PiezoelectricPiezoelectric Effect
• CarbonOhms Law

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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20A Vacuum Tube is an electronic device that
  amplifies electrical signals by permitting a
  small voltage to modulate a much larger current.

Cathode
Vin
Vout
Grid
Plate
Gain Vout /Vin
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Amplification
• Gain G Vout / Vin

Vout G Vin
Vout
Vin
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Physics 1251 Unit 4 Session 38 Analog
Recording

• 80/20A Field Effect Transistor (FET) is a solid
  state electronic device that permits
  amplification of electrical signals.

Gate
Source
Drain
Silicon Dioxide
Silicon
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Analog Recording Media
• Mechanical
• Edisons Phonograph
• Vinyl LP Records
• Magnetic
• Magnetic Tape
• Magnetic Disk
• Optical
• Audio Track on motion picture film

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Physics 1251 Unit 4 Session 38 Analog
Recording

• Mechanical
• Edisons Phonograph

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Physics 1251 Unit 4 Session 38 Analog
Recording

• Mechanical
• Edisons Phonograph
• Vinyl LP Records

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Physics 1251 Unit 4 Session 38 Analog
Recording

• Analog Recording Media
• Magnetic
• Magnetic Tape
• Magnetic Disk

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Physics 1251 Unit 4 Session 38 Analog
Recording

• Analog Recording Media
• Magnetic
• Magnetic Tape
• Magnetic Disk

Ferro-metal Oxide
Tracks
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Analog Recording Media
• Optical
• Audio Track on motion picture film

Stereo Audio Tracks
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Analog Recording Media
• Optical
• Audio Track on motion picture film

Stereo Audio Tracks
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Physics 1251 Unit 4 Session 38 Analog
Recording

• Summary
• Common types of microphones are (1) condenser
  (2) magnetic (3) dynamic (4) ribbon (5)
  piezoelectric (6) carbon.
• Vacuum tubes and transistors provide
  amplification by permitting the input to modulate
  a larger output current and voltage.
• Analog recording media include mechanical,
  magnetic and optical storage.
• Playback uses physical principles in which
  mechanical oscillations, magnetic domains and
  optical density variations produce electrical
  signals that are analogous to the recorded sound.