I’ve been hacking in this space for a long time. I think that there are a few different processes to examine:
- tape loop
- recording to a tape loop with the erase head defeated
- conventional live looping
- Dub-style “mixer send to itself” style delay and looping, shimmer
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tape loop is easy to understand: you generally record a longer piece and cut and loop it to an arbitrary length. alternately this can be emulated in many ways with digital audio. Basinski’s DL is this process + the tape destroying itself with repetition (plus a pretty aggressive comp/limiter and digital reverb)
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is frippertronics - a loop of tape runs through a tape machine with a defeated (or partially defeated) erase head. Sound on sound recording is done. The dynamics of the tape and record head control the blending of new sounds with sound on tape… allowing the player to often soften high end or transients on already recorded material with what is being recorded now.
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Live looping really got off the ground with the Oberheim EchoPlex IV and the OG Lexicon JamMan in the mid 90s and then later became ubiquitous with the Line6 DL4 and Boss Loopstation pedals. These devices allowed a foot tap to define the beginning and the end of a loop buffer that a player could record into and keep recording into. The blending of previous and newly recorded audio was a simple digital sum and there was no easy way to process audio in the feedback loop (see below) as the entire process was done within a single box. This did enable rhythmically synchronized loops, though, and some boxes included midi sync and trigger quantization. Both of these devices offered very long loops compared to what came previously as well.
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This basis of this technique was used in some frippertronic style looping, but primarily in dub production. Basically, you use a mixer send to route audio to a delay or even a looper, with the feedback on the delay or looper set to 0%. Then route the audio out of the delay looper into a track on your mixer and use the send control on THAT track as your feedback control for the delay or loop. This enables you to place other audio processes in the feedback path, including eq, delay, or other processes. Brian Eno and Daniel Llanois used this technique and variants of it to great effect by adding an up-octave pitch shift into the feedback path, creating their famous Shimmer effect.
Ableton Live and Augustus Loop opened up this kind (#4) of functionality within a DAW by including the ability to route the feedback of a looper process out and back into the looper. Bitiwg enables this by including a Delay plugin that has a feedback fx patch point.
My process now is to do just this with Bitwig, creating a delay-1 program with Augustus Loop in the feedback fx, with feedback in the AL plugin set to 0%. This enables me to insert any audio processing in the loop that I want, including routing audio out to a 3-head tape unit with record monitoring enabled and back into the DAW in the feedback loop, which provides natural tape generation/degradation and pitch modulation on each replay of the loop buffer. There are a lot of ways to process the loop buffer in this implementation, including setting up a random modulator attached to a gain control that can cut audio out of the running loop, Disintegration Loops style. I’ve also set up a toggle macro control that allows the freezing of a loop by putting feedback within Augustus Loop to 100% and turning it down to 0% in the Bitwig Delay-1, thus “pausing” the degradation.
It is also really satisfying to build “shimmer” effects using the same workflow. Eventide’s h910 plugin provides a very close replica of the hardware that Eno used on his first recordings with the effect and the H3000 Factory plugin provides a satisfactory version of what was used on later recordings. The variety of sounds that you can get with these feedback processes is pretty amazing… on Blue Day, for instance a tiny Casio calculator synth produced enormous angelic washes of sound.
