Strange loops - The INSANE math behind Autechre's Fold4, Wrap5 (feat Polyend Tracker and Nord Lead)

Summary

The video explains the idea of a restart rhythm: a musical “strange loop” that seems to change continuously but eventually returns to its starting point. The creator uses Autechre’s “Fold4, Wrap5,” from LP5 (1998), as inspiration for a short demonstration.

A restart rhythm is compared with a Shepard tone. Both create an illusion of ongoing movement without a lasting change in the overall pattern. A Shepard tone layers octave-spaced tones so that rising sounds fade out at the top as new ones enter at the bottom. A restart rhythm applies a similar principle to rhythm: it combines versions of a pattern moving at different relative rates, then changes the playback tempo and fades out patterns that become stationary or too fast to distinguish. The changing parts eventually cycle back to their original state.

How the Demonstration Is Constructed

• Drums: Two Tracker tracks provide percussion:
  • One uses the Polyend Tracker’s FM synthesizer with a random-percussion preset to play a simple rhythm.
  • The other adds hits from the Tracker’s percussion synthesizer.
• Nord Lead parts: Two Tracker tracks send notes to the same Nord channel. Because Tracker tracks are monophonic, separate tracks are needed to play multiple notes together.
• Arpeggiated part: A monophonic Nord Lead part is processed by the synth’s arpeggiator, which synchronizes to the track’s tempo.
• Tempo movement: The demonstration begins at about 128 BPM and slows to 64 BPM by the end of the loop. The intended effect is for the rhythm’s perceived density to change as the tempo shifts.
• Effect: The creator adds “Quadroverb” before presenting the resulting loop.

The creator describes the video as a mathematical construction more than a musical exposition. The piece itself changes little on the surface; its interest lies in the looping rhythmic effect.

Speakers and Sources Featured

• Speaker: The video’s creator and narrator, who explains and performs the demonstration.
• Musical reference: Autechre’s “Fold4, Wrap5,” from LP5.
• Instruments and equipment: Polyend Tracker Plus and Nord Lead 2X Rack.