3.3 Tape Delay

Tape Delay

roland_space_echo_02

  • The peak level will illuminate if the signal clips or distorts and the VU meter shows the input level in volume units.
  • The mic/instrument volume is the gain. This can be decreased to avoid clipping. It can be turned up to obtain a better signal to noise ratio.
  • The instrument volume is for a low impedance instrument such as guitar.
  • The mode selector is used to select different taps / patterns / rhythms / types of delay / number or volume of repeats / combinations of playback heads.
  • The bass and treble controls are used to modify the tone of the delay (not the dry signal). It is a shelving filter that adjusts the levels of low and high frequencies.
  • The reverb/echo volume is the wet/dry effect mix. “Straight” gives no echo at all. This is the gain, and has a spring reverb unit.
  • Repeat rate is the delay time / the amount of time between each repeat.
  • Intensity is the feedback amount/number of repeats. This is the gain.
  • The power switch should be used so that the unit should be switched off when not in use to preserve the life of the tape.
  • Echo normal or footswitch works as a bypass (to switch off the machine).
  • HML gives different output levels/volumes so that the unit can match the different signal levels required by different studio equipment.

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.

 

cassettes.png

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.