Analogue!

a mind map of everything i've learnt about analogue recording :)

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  • Analogue!
    • Recording mediums
      • Magnetic tape - analogue
      • Vinyl - analogue
      • Hard disc/CD - digital
      • DAT - digital
      • Mini Disk - digital
    • Disadvantages of analogue
      • Unreliable - inconsistency
      • Hi-Fidelity - quality deteriorates over time
    • ANALOGUE DEFINITION: a recording in which a property of a physical recording medium is made to vary in a manner analogous to the variations in air pressure of the original sound
      • The magnetisation of magnetic tape
      • The shape of the groove of a gramophone disk
    • Early records
      • Made from a shellac compound
        • Brittle
        • Noisy
        • Used a much larger groove
        • Played at 78rpm
          • Limit of 5 mins per side on a 12 inch record
        • Mono sound
        • Poor frequency response
          • 168-2000Hz
          • Poor dynamic range
    • The 'LP'
      • Introduced by Columbia Records in 1948
      • Made from vinyl
        • 10 or 12 inch
        • Finer grooves
          • 'Microgroove' stylus
        • Played back at 33 1/3 rpm
        • Each side played for more than 20 mins (12 inch)
        • 45rpm format focused on singles
    • Hi-Fidelity Sound
      • Frequency Range - steadily increased to 30-30,000Hz
      • Dynamic Range - 65db compared to a CD of 90db
      • Improved signal-to-noise ratio
      • Stereophonic sound (stereo)
    • Tape
      • Three main layers
        • Top coating
        • Magnetic Oxide
          • Attached with a binder to a long thin plastic *****
        • Polyester Base (PVC)
      • Wound onto a spool reel
      • How it works
        • A record head charges the fine metal particles on the tape
          • The strength of magnetisation correlates directly to the electrical signal
      • Parts of an analogue tape recorder
        • Tension arm
        • Guide
        • Erase head
        • Tape lifters
        • Record head
        • Play head
        • Capstan
        • Pinch roller
      • The faster the tape speed, the higher the quality
        • More high frequencies
      • Track count
        • Number of tracks depends on width of tape
        • 2 inch tape - 16-24 tracks
        • 1 inch tape - 8-16 tracks
        • 1/2 inch tape - 2-16 tracks
        • 1/4 inch tape - 1-8 tracks
        • 1/8 inch tape - 2-8 tracks
        • Each track needs a separate recording head
      • Tape speed
        • Controlled by capstan
        • Measured in IPS (inches per second)
          • Typical speeds are 30, 15 and 7 1/2 IPS
        • A typical compact cassette runs at a slow 1 7/8 IPS
        • The faster the tape speed, the higher the quality and the lower the background noise or hiss
          • Other factors that affect the quality:
            • Tape width
            • Chemical properties
            • Thickness
      • Wow and Flutter
        • Changes in pitch caused by small speed changes of mechanical parts
        • Can be introduced during recording or playback phase
      • Tape Saturuation
        • Overload of a magnetic tape
          • Input signal too high when passing from the record head to the tape
        • Warm, rich sound
        • Harmonic distortion
        • Said to be one of the best qualities of analogue tape
      • Frequency response
        • Non-linear
          • Have to physically move through the tape to 'punch in' on a section
            • Editing is possible by physically cutting and splicing
        • May vary according to:
          • Input signal strength
          • Tape/machine used
        • Can be corrected by:
          • Using an AC bias
          • Using a pre-emphasis EQ
      • Tape degradation
        • Need to be kept in optimal environment
        • Tape heads need cleaning
          • Removes oxide build up
        • Binder (glue) deteriorates
        • Avoid magnetic sources

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