3.3 Introducing Tapes

What a Tape Is Made Of

  • They contain two reels of magnetic tape. The tape is coated with iron oxide.
  • The sound quality of cassette tape is not as good as studio tape, with a reduced high frequency response because the tape moves slowly at 1 and 7/8 inches per second, and the tape is narrow.
  • The speed of the tape is controlled by the capstan or pinch roller.
  • Mono tapes have one track on each side (so two in total)
  • Stereo tapes have two tracks on each side (so four in total)
  • Multitrack tapes have four tracks but only play one way
  • Tape lengths are 60, 90 and 120 minutes, but 120 minute tapes often snapped
  • Tapes had erase protection tabs which meant that when broken, a tape could not be recorded on.
  • Tapes could be ‘dubbed’, which raised concerns about piracy, especially when a technology called ‘high speed dubbing’ was developed.



Drawbacks of Tape

  • Cassette tapes are prone to hiss, so Dolby Noise Reduction was developed. This boosts the high frequencies when recording and reduces them on playback.
  • Tape saturation occurs when an increase in the strength of the sound source and thus electrical signal cannot produce an equivalent increase in magnetisation on the tape head. This leads to a form of subtle compression.
  • Cassette tapes can stretch
  • Iron oxide wears off tape over time which means that an oxide build up can occur on the tape head
  • Thus many companies marketed tape head cleaning cassettes which, combined with a chemical, removed oxide from the tape heads.
  • Cassette tapes are prone to print through, which is where the music is heard as an echo before it plays
  • Tape has a leader tape, which cannot be recorded on. This lasts for 2-3 seconds and draws the tape through onto the other reel.