Audio Damage Liquid - Manual (Page 8)

low-frequency oscillator (LFO) could be used to change the delay time slightly to create the effect of someone
dragging their fingers on the tape-reel flange. Later digital delays were substituted for the BBD chips, with
results of debatable virtue. Flangers became available as rack-mount studio hardware, stomp boxes for
guitarists, and (some years later) software plug-ins.
Note, however, that there’s a fundamental difference between using a single delay line to create flanging and
using two tape decks: with a single delay line, the relative delay time between the two signals will never reach
zero. Any form of electronic delay circuit has at least a very small delay time. The term through-zero flanging
refers to the phenomenon when flanging is created in such a manner that the relative delay time reaches—
and passes through—zero, creating negative delay times. (A negative delay time sounds like something from
a science-fiction story, but it simply means that the relative delay time between the two signals has changed;
that is, the tape deck that used to be behind has caught up with, and passed, the other tape deck.) Through-
zero flanging is more difficult to create, but can produce different and more dramatic effects than the single-
delay flanging that we of the post-tape era have become accustomed to.
Liquid uses two varying delay lines to create true through-zero flanging. The two delay lines are changed in
opposite directions to produce positive, negative, and zero relative delay times. Liquid also applies a gentle
amount of filtering to the delayed signals to reduce the metallic-sounding harshness often associated with
flangers based on digital delays (either hardware- or software-based delays).
So why is flanging associated with jet airplanes? It could be because the sound from the engine travels in two
paths: one straight to the listener’s ear, and one that bounces off the surface of the runway. The bounced
sound takes slightly longer to reach the ear, so a short relative delay time is created, producing comb filtering.
Or it could be because we all heard the prominent use of flanging in the song “Jet” by Paul McCartney & Wings
one too many times.