Techniques of tape manipulation

Tape manipulation

There was probably no technology more essential to the evolution of electronic music than the medium of magnetic tape.

Tape introduced the portability and malleability needed to record, edit and manipulate sound, as well as to play back the music at a range of venues around the world. There are a wide range of musical techniques afforded to the electronic composer by working with magnetic tape. Here are some of the more commonly encountered techniques:

Recording and playing sounds

Perhaps the most obvious technique in the use of tape manipulation is the way that magnetic tape allowed composers to record and playback a wide range of sounds, instruments and musical phrases.

Reversing sounds

By inverting the direction of the magnetic tape composers were able to reproduce a sound in reverse, creating that unique ‘sucking’ sound as recordings seem to retreat back to their starting point.

Playback speed

Changing the speed of playback allowed composers to transpose a sound up and down in pitch. Tape machines often varied between playback speeds of 3.75, 7.5 and 15 inches-per-second (i.p.s.) By recording a sound at 7.5 i.p.s. and playing it back at either of the other two speeds, the sound could be transposed up or down an octave by playing it back at half or twice the original speed. This can then be compounded by re-recording and re-transposing sounds multiple times.

There are other ways to change the speed of playback in more subtle ways. By placing some slight pressure on the tape spools it’s possible to pitch bend a sound by very slightly affecting the speed in which the tape passes by the tape head. Of course, changing the speed of sound also changes the duration of a sound too – when slowing a sound down to half speed it would necessarily take twice as long to playback in its entirety. Similarly, speeding up a sounds playback at double speed means it would playback in half the time of the original. So here we can see that the technology of electronic music necessarily informs a set of relationships between the sound materials’ pitch and duration.

Splicing sounds together

Unlike recordings made to acetate discs, the relative fragility of magnetic tape offered composers the opportunity cut and splice recordings together in different physical combinations. It may sound typical to us now, but this ability to cut one recording into another recording meant that for the first time, composers were able to edit sounds in ways not bound by physical limitations.

Mixing sounds

In addition to splicing recordings together, through the use of a mixing desk it was possible to combine different sound sources onto a single recording. As such, it was possible to create sounds comprised of many different layers of recordings, or sounds which utilised different parts of its component recordings.

Looping recordings

One of the most striking elements of composing with magnetic tape was the ability to splice together two ends of tape, creating a circular loop that would run repeatedly across the tape machine play head. This allowed for composers to create rhythmic sequences or cycles of entire sequences of material.

Over to you

Which of these techniques can you already recognise in the music we’ve listened to so far? What techniques can your recognise in the music you listen to outside of this class? If you use a DAW, what parallels can you see between these techniques and the Digital Audio Workstation?

References

Chion, M. (2016) Michel Chion’s analog tape techniques. Published 20 July, 2016. https://designingsound.org/2016/07/20/michel-chions-analog-tape-techniques/