During World War II, whilst radio reporters in the battlefields
of Europe were preparing their recordings on shellac-coated
disks, the Nazi propaganda machine was broadcasting material
prepared on the recording machine of the future. This was the
magnetophon — the first tape recorder.
At the end the war the arrival in Britain of these advanced machines was rather a shock. EMI proceeded to built their own machine, the BTR/1, based on the German originals. Like many continental machines the tape heads faced away from the operator, making editing rather tricky! This was corrected in the next machine, the BTR/2, a huge console recorder, many of which remained in BBC service until the seventies.
Miniature valves made it possible for EMI’s smallest machines, the TR/90, to fit into a standard 19" rack, or even into a mobile trolley. All of these professional machines incorporated three tape heads — erase, record and replay — allowing the user to check the quality ‘off tape’ whilst recording.
But in Britain perhaps the most significant machines of all were those destined for the semi-professional or amateur market, notably the Ferrograph, beginning with the Series One, remaining virtually unchanged until the Series Five, followed by the rather more modern Series Six and Series Seven machines.
Indeed it was the enthusiastic amateur and experimenter who often saw the real potential for the tape recorder. Although it could be used, aided by a dextrous razor blade, for the purposes of propaganda, it could also be used to creatively change the nature of recorded sound.
Advocates of musique concrète saw the machine’s ability to create new sounds from old — using snatches of ‘spooling noise’, playing the tape backwards, at different speeds, or even by turning the reels by hand.
By using a machine with a variable speed capstan motor it was possible to change the pitch of a recorded sound with some degree of musical accuracy — the BBC Radiophonic Workshop used a Leevers-Rich machine fitted with a rotary switch calibrated in musical intervals.
Tape Sampling
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All of the principles of what we now call sampling were soon established. Any source material could be used and processed in any manner — the only limitation was imagination! Many sources were familiar to drama studios — breaking glass; gravel in boxes; the percussive use of musical instruments, bottles or metal tanks; machinery and street sound.
The process demanded a clean recording of the original sound. Its start and finish would be trimmed using razor-blade editing, as necessary. If the sample was not at the desired pitch the recording would be dubbed (copied) from a varispeed machine onto a standard recorder, using separate ‘passes’ for different pitch settings. Finally all the samples, modified or otherwise, would be edited together into a continuous sequence by means of a razor-blade, editing block and splicing tape.
To create very long cross fades a special editing block would be used — this featured a very shallow splicing angle. Any sample could be made into continuous sound by splicing together the ends of a recording to form a loop.
„ Samples, unlike synthesised sounds, contain all the complex harmonics,
and harmonic decay, of natural sounds. The effect can be disconcerting or
dramatic, as demonstrated by the sounds of dinosaurs in Jurassic Park,
created from those of real animals. But as the pitch is moved further away
from that of the original it develops characteristics different from real
sounds — the pitch change alters the subjective ‘size’ of a sound but
ignores the physical properties of the materials that created it.
„ The harmonic content of real instruments varies considerably across the
musical scale — every note on a piano is different, each string vibrating the
others differently, changing as the note decays.
Time Delays
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Having discovered the useful delay introduced between the record and replay heads of a tape machine, the pioneers explored the possibilities of running a tape from the left hand spool of one tape machine to the right hand spool of another, passing both sets of record and replay heads.
By drawing the tape out between the machines on a sprung loop stand it was possible to extend the delay of the output from the second machine. Furthermore the audio output of the second machine could be mixed back into the input of the first machine to create sounds rising and falling, under careful control, in ‘waves’. The guitarist Robert Fripp was so enamoured with this trick he christened it Frippertronics, many years after it was first used.
Phasing and Flanging
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Two other effects which came briefly to popularity were phasing and flanging, both caused by upsetting the azimuth (the vertical angle of the tape head) during recording or playback — perhaps by touching the flange of one spool.
Phasing was the result of combining the input and output of a tape machine (or the two outputs on a stereo machine). As the phase between the two signals changed the output at a certain frequencies (and their harmonics) was cancelled out — an effect identical to a comb filter.
Flanging, on the other hand, relied on feeding some of the output back to the input, verging on oscillation at some frequencies. The result was much more metallic.
Neither could be described as musical, but they could be dramatic!
Stretching the Tape
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The success in tape manipulation spawned some novel devices. One was the Binson Echorec which had a spinning metal drum, surrounded by tape heads, so as to produce multiple delays.
Another, the Tempophon, was strapped to the side of a tape machine — with the tape passing a spinning replay head. Since the speed of the tape in relation to the this head was set by the Tempophon itself, irrespective of the actual speed of the tape, it was possible to vary the pitch without altering the tempo.
The BBC’s Programme Effects Generator (PEG) provided ‘spot effects’ for radio drama such as The Archers. This device used a separate tape cartridge for each effect, the tape being pulled out of the cartridge, played and then drawn back in again.
A further development of PEG was the Mellotron, a keyboard instrument with cartridges containing sampled instruments. The Moody Blues used it successfully in their sixties ‘symphonic’ rock music — despite the sluggish mechanism. Roland also used tape cartridges — this time as a loop providing very long delays for an effects device.
At the Radiophonic Workshop a number of tape machines could be coupled to an audio multiplexer, to create a montage of sounds. The multiplexer consisted of a circle of fixed capacitor vanes, to which the tape machines were connected. The output came from a rotating vane, driven by a variable speed motor. As this turned it received each input in sequence, one sound fading into the next.
Reverberation and Sound Processing
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Reverberation has always been popular — it covers small blemishes and gives any recording a consistent feel or atmosphere. Echo rooms, plates and springs were common. Spring usually gave awful results but hitting the device produced dramatic sounds! One popular trick involved copying a tape backwards whilst adding reverb, then playing it forwards to give reverse echo.
Equalisers, preferably of a graphic form, were much in vogue for musique concrète. Passive versions, comprising simply of coils and capacitors, could provide a remarkable degree of ‘Q’, enabling dramatic changes to be made to any sound.
At the Radiophonic Workshop the mechanical ‘Dalek’ voices for Doctor Who were created using a ring modulator, consisting of three audio transformers and a ring of four diodes. Untreated speech was applied to the ‘main’ input whilst a low frequency (usually upwards of 15 Hz) was applied to the ‘carrier’ input.
In the seventies a range of new products began to erode the value of tape effects. These included delay lines, phasers and flangers, often using analogue bucket brigade devices (BBDs). Although primitive by today’s standards, they were more convenient than ‘hit and miss’ tape techniques — and quality was not impaired by tape noise or saturation.
 The acceptance of the Compact Cassette as a universal
recording standard safely enclosed magnetic tape in a plastic
shell. But by the late eighties digital processing had made tape
