1. Fundamentals of Audio Production
Chapter Six:
Recording, Storing, and Playback of Sound
Fundamentals of Audio Production. Chapter 6.

2. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
The phonograph – cylinder recorder/player developed by Thomas Edison.
Fundamentals of Audio Production. Chapter 6.

3. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Gramophone – Emil Berliner’s disk-based mechanical recorder
Fundamentals of Audio Production. Chapter 6.

4. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
By “shouting into the funnel,” a diaphragm at the small end would vibrate
A stylus attached to the diaphragm would vibrate and cut a groove into the cylinder or disk
On playback, the stylus would track through the groove, causing vibrations in the diaphragm, which echoed through the funnel
Fundamentals of Audio Production. Chapter 6.

5. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Modern record cutting lathes use electromagnetic heads to convert audio current into physical vibrations
The electromagnets respond to audio current by alternatively pushing/pulling the stylus
The vibrating stylus is heated to easily cut a groove in the vinyl disk
Fundamentals of Audio Production. Chapter 6.

6. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Fundamentals of Audio Production. Chapter 6.

7. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Fundamentals of Audio Production. Chapter 6.

8. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Modern phonographs use electromagnetic transducers called cartridges
Cartridges convert potential physical energy, which is stored in the grooves of the recording, into electrical energy
The stylus follows the undulating groove
Movements of the stylus, vibrate a small magnet/coil mechanism
Fundamentals of Audio Production. Chapter 6.

9. Fundamentals of Audio Production. Chapter 6.
Mechanical storage
Fundamentals of Audio Production. Chapter 6.

10. Magnetic tape recording
Magnetic recording heads are transducers that convert electrical energy into magnetic energy
Recording heads are electromagnets
Audio current creates an alternating magnetic field
The magnetic field is focused at the “gap” in the record head
Fundamentals of Audio Production. Chapter 6.

11. Magnetic tape recording
Fundamentals of Audio Production. Chapter 6.

12. Magnetic tape recording
The fluctuations in the magnetic field are stored on tape by re-arranging the magnetic polarity of the “metal” surface of the tape
The tape surface is made from powdered metals, like FeO2, or iron oxide (rust)
The metals are attached to a plastic backing with binder (glue)
Fundamentals of Audio Production. Chapter 6.

13. Magnetic tape recording
Playback heads are constructed in a nearly identical manner
During playback, a current is induced to flow in the coil of the head by the magnetic charges of the tape surface
Fundamentals of Audio Production. Chapter 6.

14. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
The paths on the tape where audio is recorded are called “tracks”
The inputs on the recorder are called “channels”
Stereo formats are two channel, but may be two or four tracks
Fundamentals of Audio Production. Chapter 6.

15. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Fundamentals of Audio Production. Chapter 6.

16. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Tape width and track spacing affect cross talk between tracks
Tape speed affects fidelity
Higher tape speeds produce greater signal-to-noise ratios
Higher tape speeds produce wider frequency responses
Fundamentals of Audio Production. Chapter 6.

17. Analog tape recording The Philips compact cassette
and track configuration
Fundamentals of Audio Production. Chapter 6.

18. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Reel to reel
Fundamentals of Audio Production. Chapter 6.

19. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Reel to reel
Fundamentals of Audio Production. Chapter 6.

20. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Cartridges
Fundamentals of Audio Production. Chapter 6.

21. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Commonalities across tape platforms
Head arrangements
First erase, second record, and last reproduce
Capstan and pinch roller squeeze together and pull the tape
Fundamentals of Audio Production. Chapter 6.

22. Fundamentals of Audio Production. Chapter 6.
Analog tape recording
Fundamentals of Audio Production. Chapter 6.

23. Digital tape recording
Digital audio tape stores binary data (on/off) represented by short bursts of electrical current
Stationary head systems (DASH) use reel-to-reel tape transports
DAT systems use helical scanning rotating head
Fundamentals of Audio Production. Chapter 6.

24. Digital tape recording
Fundamentals of Audio Production. Chapter 6.

25. Fundamentals of Audio Production. Chapter 6.
Optical storage
Electrical energy is converted into light energy by a LASER
The LASER burns microscopic pits into the surface of a glass disk
Binary data (on/off) triggers the LASER
Fundamentals of Audio Production. Chapter 6.

26. Fundamentals of Audio Production. Chapter 6.
Optical storage
Fundamentals of Audio Production. Chapter 6.

27. Fundamentals of Audio Production. Chapter 6.
Optical storage
Compact disks are read by a LASER
Light is refracted into a photoreceptor by “bumps” on the surface of the disk
Each pulse of light is equal to an “on” state
Fundamentals of Audio Production. Chapter 6.

28. Fundamentals of Audio Production. Chapter 6.
Optical storage
Fundamentals of Audio Production. Chapter 6.

29. Fundamentals of Audio Production. Chapter 6.
Optical storage
The pits made by the LASER are .5 microns wide and up to 3.5 microns in length
How big is that?
Data is stored redundantly on the disk to avoid destruction or obliteration by dirt
Fundamentals of Audio Production. Chapter 6.

30. Fundamentals of Audio Production. Chapter 6.
Solid state storage
“Flash” memory is constructed from layers of layers of conductive and non-conductive materials
The layers function as transistors
Current is passed through the device’s thousands of transistors
If it passes through, it represents an “on” in binary code
Fundamentals of Audio Production. Chapter 6.

31. Fundamentals of Audio Production. Chapter 6.
Solid state storage
Fundamentals of Audio Production. Chapter 6.

32. Fundamentals of Audio Production. Chapter 6.
Solid state storage
Fundamentals of Audio Production. Chapter 6.

33. Fundamentals of Audio Production. Chapter 6.
Discussion
What are the relative advantages and disadvantages of
Mechanical
Magnetic
Optical
Solid state
Fundamentals of Audio Production. Chapter 6.