Analog Recording

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Analog Recording
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A Brief History of Sound Recording

• Before actual sound recordings existed, several
  mechanical formats were developed to reproduce
  music. These included devices such as
• Musical Clocks (1598)
• Barrel Organs (1600s)
• Barrel Pianos (1805)
• Musical Boxes (1815)
• Player Pianos (1876)

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Musical Clock
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Barrel Organ
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Barrel Piano
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Musical Boxes
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Player Pianos
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The first recordings

• The first two formats for recording sound were
• 1) Cylinder Phonograph (1877) by
• Thomas Edison
• 2) Gramophone Record (1889) Emile Berliner

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Cylinder Phonograph
Edisons first sound recording
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Gramophone Record
Emile Berliner with Gramophone record player
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Development of Electronic Formats

• Throughout the 20th Century many different
  electronic inventions were made to make the
  recording and reproduction of sound more accurate
  and efficient.

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Telegraphonemagnetic wire recording by Valdemar
Poulsen(1898)
The first answering machine
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Triode vacuum tube by Lee De Forest ?
Amplification
Audion (1906)
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Regenerative Circuit (1914-1922) by Edwin
Armstrong ? Radio
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Condenser Microphone (1917) by E.C. Wente of
Bell Labs
late 20s condenser mic
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Victor Talking Machine (1924) Bell Labs
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Columbia Phonograph Co. (1924) Bell Labs
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Ribbon Microphone (1925) RCA
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Sound-On-FilmRCA Photophone (1925)
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Stereo recording patented (1931) Alan Blumlein
-EMI
Blumlein Pair Array(2 crossed Figure-8s)(Small
arrows indicate front of individualmicrophones,
large arrow indicates front of array.)
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Marconi-Stille Recorder-steel tape recording
(1932) used by BBC
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Telegraphone/Magnetophone-acetate tape recording
(1935) BASF
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Shure Unidyne-cardiod dynamic mic (1938)
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Ampex Model 200 (1948) ¼ tape and 10 ½ reels
Jack Mullin
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Microgroove Long Playing Records 33 1/3 RPM
(1948) Dr. Peter Goldmark-Columbia Records
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45 RPM single (1949) RCA Victor
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Multi-Track Tape Recorder-modification of Ampex
Model 300 (1950) Les Paul
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Ampex 1 eight track tape developed for Les Paul
(1954)
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8 Track Sel-Sync recording (Selective Synchronous
Recording)-Les Paul (1956)
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Stereo Records (1958)
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Mixer Rupert Neve (1961)
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Compact Cassette (1963)
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8-track tapes (1964)
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Automatic Double Tracking (ADT) (1966)
synchronizing two 4 track machines Ken Townshend
at Abbey Road
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Ampex MM-100016 track recording (1967)
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TASCAM, TEAC, OTARI , AMPEX and STUDER - 24 track
recording (1973)
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MCI -32 track recording at 20 IPS inches per
second(1978)
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Tascam Portastudio 4 tracks on a cassette (1979)
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An Introduction to Tape Recording

• How does analog tape recording work?

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Tape Recording

• An acoustic sound source creates waves in the
  air. These waves are continuously varying in air
  pressure.
• A microphone capsule responds to changes of air
  pressure.
• As the diaphragm moves a variance in the flow of
  electrons is induced. This variation in the flow
  of electrons from the microphone is amplified and
  routed to the record head.
• The record head responds to the microphone signal
  by converting the electrical signal into a
  continuously changing magnetic flow.
• Changes in magnetic flow are imprinted on the
  recording tape and stored for playback.

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Tape Recording (continued)

• The playback head is constantly in a state of
  being magnetized by the tape. The tape induces a
  continuously varying magnetism in the playback
  head.
• The varying magnetic flow from the play back head
  is converted into an electrical signal that is
  sent back to the mixer or input of the power amp.
  
• The power amplifier boosts the level of the
  original signal enough to move a speaker cone
  back and forth in the same way that the
  microphone capsule was moved in the first place.
• As the speaker cone moves back and forth it
  creates continuously varying changes in air
  pressure (waves).
• The speaker cone movement should be an exact
  replica of the waves created by the original
  sound source as it was captured by the microphone.

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Why do many audiophiles still prefer analog tape
recordings?

• Analog recording is considered to be more
  accurate than digital recording because it
  captures a continuously variable change in air
  pressure. This system reflects the original
  waveform in the most accurate way.

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The anatomy of the analog tape mechanism
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There are several significant disadvantages to
analog recording

• Poor signal to noise ratio
• Cumbersome and bulky equipment is involved
• Tape degrades with each progressive play over the
  tape head
• The equipment is mechanical therefore it is prone
  to failure.
• Lots of care and maintenance is needed (head
  cleaning, degaussing)

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Disadvantages (continued)

• Editing of parts is difficult (punching in and
  out)
• Editing of the master is done with a razor blade.
  There is no undo!!
• Tape is fairly expensive (175 for 24 track tape
  that holds only 16 minutes)
• Requires special care when storing (tails out to
  avoid print through and also under specific
  temperature and humidity conditions) Tapes should
  be stored in a cool, dry environment between 50
  F and 70 F, 20 to 45 relative humidity. Lower
  numbers are better for longer-term storage.

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Disadvantages (continued)

• Cueing to a specific position on a track is more
  difficult.
• Automation of mixing functions is rare and
  expensive.
• Each successive copy of the original has a poorer
  sound quality.
• Despite these pitfalls, many musicians still
  prefer analog recording.

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The quality and capability of analog tape
recording is determined by several factors

• Width of the tape
• i) cassettes are 1/8 wide
• ii) reel to reel tapes are 1/4, 1/2 , 1 or 2
  wide

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Factors that determine quality and capability of
tape recording (continued)

• Speed of the tape
• i) cassettes (1 7/8 IPS inches per second)
• ii) 4 track cassettes (3 ¾ IPS)
• iii) ¼ inch reel to reel (7 ½ IPS)
• iv) ½ and 1 reel to reel (15 IPS)
• v) 2 reel to reel (30 IPS)
• A faster tape-speed produces a higher quality
  recording

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Factors that determine quality and capability of
tape recording (continued)

• Number of tracks
• i) cassettes (8 tracks at mostusually 4)
• ii) ¼ reel to reel (varies from 2 to 8 tracks)
• iii) ½ reel to reel (varies from 2 to 16 tracks)
• iv) 1 reel to reel (8 or 16 tracks)
• 2 reel to reel (16 or 24 tracks)
• Fewer tracks on a wider tape usually mean that
  there will be a lower chance for the occurrence
  of cross-talk (fringing) between tracks. This is
  when signals from one track bleed over to
  another.

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Factors that determine quality and capability of
tape recording (continued)
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Factors that determine quality and capability of
tape recording (continued)

• The type of magnetic oxide particles found on the
  tape
• i) Iron Oxide
• ii) Chromium Dioxide
• Chromium dioxide provides better signal to noise
  ratio and a wider dynamic range

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Factors that determine quality and capability of
tape recording (continued)
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Factors that determine quality and capability of
tape recording (continued)

• Amount of Wow and Flutter
• This is a measure of the change in recorded
  frequency due to the variation in tape speed of
  the recorder. Wow and flutter cannot be corrected
  after the recording is made so you are stuck with
  what you have.

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Factors that determine quality and capability of
tape recording (continued)

• Type of Noise Reduction that is used
• Dolby Laboratories created several methods of
  reducing tape hiss on analog recordings. Dolby
  developed an encoding and decoding system of
  noise reduction.
• Types of Noise Reduction
• a) Dolby B-type Noise Reduction 10 dB of noise
  reduction
• b) Dolby C-type Noise Reduction 20 dB of noise
  reduction
• c) Dolby S-type Noise Reduction 24 dB of noise
  reduction and reduces low frequency noise by
  10db.
• d) DBX Noise Reduction- Professional level
  technology that involves compression as a portion
  of the signal is boosted to avoid tape saturation
  and distortion. This system reduces tape hiss
  while still maintaining a widedynamic range in
  the recording.

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Factors that determine quality and capability of
tape recording (continued)
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Interesting Analog Recording Tricks

• Variable speed recording Recording sounds at a
  slower or faster tape speed allows the artist to
  record a track at half or double speed to alter
  the tempo and pitch of a part by an octave up or
  down. Popularized by Alvin and the Chipmunks,
  Mike Oldfield and Les Paul.
• Ex. Sombreros (A. Shoesmith)

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Interesting Analog Recording Tricks (continued)

• Backwards masking
• Flipping the tape over and recording a part
  backwards will yield interesting results when
  flipped back over.
• Ex.1 Pink Floyds Empty Spaces
• Ex. 2 Beatles Rain