Physics 1251 The Science and Technology of Musical Sound Unit 4 Session 38 MWF Analog Recording and Playback Unit 4 Session 38 MWF Analog Recording and Playback

Physics 1251Unit 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.

Physics 1251Unit 4 Session 38 Analog Recording 1′ Lecture: Recording requires a transducer, such as a microphone, to produce an electrical signal. 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. 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. Recording also requires amplification as well as a storage medium. Analog recording media include vinyl record, magnetic tape, magnetic disk and optical film. 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. Playback uses physical principles in which mechanical oscillations, magnetic domains and optical density variations produce electrical signals that are analogous to the recorded sound.

Physics 1251Unit 4 Session 38 Analog Recording 80/20 An electric guitar uses a magnetic pickup that produces an electrical signal by a time-varying magnetic field. Steel Guitar String PickupNS

Physics 1251Unit 4 Session 38 Analog Recording 80/20 The Faraday Effect : a magnetic field that varies in time produces a voltage and current in a coil. N S Current

Physics 1251Unit 4 Session 38 Analog Recording 80/20 A Condenser Microphone uses electric induction to produce an electrical signal. Voltage V Current I ++++ Charge = V (ε o S/x)

Physics 1251Unit 4 Session 38 Analog Recording 80/20 Magnetic Microphone: a small magnet, attached to a moving diaphragm induces a voltage and current in a coil. Voltage V Current I

Physics 1251Unit 4 Session 38 Analog Recording 80/20 Dynamic Microphone: a diaphragm moves a small coil in a magnetic field inducing a voltage and current. Voltage V Current I N N S

Physics 1251Unit 4 Session 38 Analog Recording 80/20 A Ribbon Microphone uses a light weight ribbon of metal moving in a magnetic field to produce electrical signals. Current I Voltage V NS

Physics 1251Unit 4 Session 38 Analog Recording 80/20 Piezoelectric Microphone: a thin crystal is bent which produces a small voltage. Voltage V

Physics 1251Unit 4 Session 38 Analog Recording 80/20 Carbon Microphone: a diaphragm compresses a sealed container of carbon granules, changing its resistance. Voltage V Current I I = V/R

Physics 1251Unit 4 Session 38 Analog Recording Microphones: Electrostatic—Induction Electrostatic—Induction CondenserCondenser Magnetic—Faraday Effect Magnetic—Faraday Effect MagneticMagnetic DynamicDynamic RibbonRibbon Piezoelectric—Piezoelectric Effect Piezoelectric—Piezoelectric Effect Carbon—Ohm’s Law Carbon—Ohm’s Law

Physics 1251Unit 4 Session 38 Analog Recording 80/20 A Vacuum Tube is an electronic device that amplifies electrical signals by permitting a small voltage to modulate a much larger current. V out Cathode Plate Grid V in Gain = V out /V in

Physics 1251Unit 4 Session 38 Analog Recording Amplification: Gain G = V out / V in Gain G = V out / V in V out V in V out = G V in

Physics 1251Unit 4 Session 38 Analog Recording 80/20 A Field Effect Transistor (FET) is a solid state electronic device that permits amplification of electrical signals. Source Gate Drain Silicon Silicon Dioxide

Physics 1251Unit 4 Session 38 Analog Recording Analog Recording Media: Mechanical Mechanical Edison’s PhonographEdison’s Phonograph Vinyl LP RecordsVinyl LP Records Magnetic Magnetic Magnetic TapeMagnetic Tape Magnetic DiskMagnetic Disk Optical Optical Audio Track on motion picture filmAudio Track on motion picture film

Physics 1251Unit 4 Session 38 Analog Recording Mechanical: Edison’s Phonograph Edison’s Phonograph

Physics 1251Unit 4 Session 38 Analog Recording Mechanical: Edison’s Phonograph Edison’s Phonograph Vinyl LP Records Vinyl LP Records

Analog Recording Media: Magnetic Magnetic Magnetic TapeMagnetic Tape Magnetic DiskMagnetic Disk Physics 1251Unit 4 Session 38 Analog Recording

Analog Recording Media: Magnetic Magnetic Magnetic TapeMagnetic Tape Magnetic DiskMagnetic Disk Ferro-metal Oxide Tracks

Physics 1251Unit 4 Session 38 Analog Recording Analog Recording Media: Optical Optical Audio Track on motion picture filmAudio Track on motion picture film Stereo Audio Tracks

Physics 1251Unit 4 Session 38 Analog Recording Analog Recording Media: Optical Optical Audio Track on motion picture filmAudio Track on motion picture film Stereo Audio Tracks

Physics 1251Unit 4 Session 38 Analog Recording Summary: Common types of microphones are (1) condenser; (2) magnetic; (3) dynamic; (4) ribbon; (5) piezoelectric; (6) carbon. 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. 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. 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. Playback uses physical principles in which mechanical oscillations, magnetic domains and optical density variations produce electrical signals that are analogous to the recorded sound.