tags: mus-407 delay delay-line

Variable Delay Effects

Variable delay effects are [digital delay effects] in which delay time changes dynamically.

Imagine a tape loop as an analogy to a [circular queue]:

• read/write pointers as play/record heads
• instead of pointers advancing, tape moves underneath heads

Essential behavior of variable delay:

• delay time (distance) between read pointer and write pointer varies
• as delay time increases, read pointer lags behind write pointer, reading through samples more slowly, causing a downward pitch shift
• as delay time decreases, read pointer catches up to write pointer, reading through samples more quickly, causing an upward pitch shift
• delay time usually driven by [oscillator] or [noise] generator

Within the circular buffer:

• distance between read and write pointer is modulated
• modulates the delay time
• modulation [envelope] and determines the shape of effect over time

This variable delay creates varying levels of [constructive and destructive interference].

• delay time can line up with various [harmonic]s to boost their [resonance]
• through destructive interference, delayed [wet signal] can also remove odd harmonics - basis for [pitch shifting]