Audio Damage Liquid - Manual (Page 7)

The Tao of Flanging
The effect known as flanging originated in the late 1960s, back when music was recorded on magnetic tape
handled by large machines rather than on magnetic discs in computers. To create doubled vocal effects, the
same recording was played on two different tape decks with their outputs mixed together. Since the two decks
started playing at slightly different times, the signal from one deck was delayed slightly with respect to the
other. This created a doubled vocal effect without requiring the vocalist to sing the same vocal part again.
Someone noticed—probably by accident—that if the two recordings were started at very nearly the same time
an interesting timbral effect resulted. The two signals were not heard separately but as a filtered version of
the original recording. This form of filtering created by delaying a copy of a signal by a fixed amount and
mixing it with the original signal, is called comb filtering because it creates a series of deep notches in the
signal’s frequency spectrum which someone once thought was reminiscent of a comb. The effect became even
more interesting if one tape deck was slowed down slightly, causing the relative time of delay between the
two signals to vary slightly. One could slow down a tape deck simply by pressing a finger or two on the flange
of one of the reels of tape; hence the term flanging was coined to describe the effect.
(If you’re getting bored with this history lesson, you can skip ahead to the Operation section below. This
material will not be on the exam.)
Everyone thought flanging was a very cool effect, but it was cumbersome to create. You needed two copies on
tape of whatever signal you wanted to use, you needed two tape decks, and you needed a good deal of
patience. Obviously using it on stage was out of the question. Hence electronic imitations of tape-based
flanging were invented.
The first such invention was the phase shifter. Phase shifters used a special form of analog filter called an all-
pass filter which creates a very short delay whose length is dependent on the frequency of the signal. This
delay time was much shorter than the several milliseconds of delay needed for flanging, but it was enough to
create a couple of notches in the frequency spectrum and hence a vague approximation of flanging. It was an
interesting enough effect in its own right that it remains popular to this day, particularly when used with
guitar or electric piano. If you’d like to add a phase shifter to your effects arsenal, Audio Damage has a fine
phase-shifting plug-in called Phase Two. Phase Two is a meticulous software recreation of the Mu-Tron Bi-
Phase, one of the most famous and sought-after phase shifters.
Some years later, with the advent of analog bucket-brigade delay (BBD) circuits, it became possible to create
a real-time flanger. A BBD chip could be used to create the necessary delay time of a few milliseconds, and a