User Manual

SA240 Mercury Flanger User’s Guide 9
Basic Flanger Operation
Flanging is a delay effect that has been used in recording studios since the late 1960s. The original
effect relied on using two tape machines playing the same tape simultaneously, with their outputs
combined.
By touching the flange of one of the tape players, the corresponding reel will slow by a small amount,
introducing a delay into the signal. The flange is then released, and the tape returns to its original
speed. The flange for the other tape player is then touched, causing it to slow down slightly, and the
process is repeated. This creates a slowly modulating difference in timing between the two tape
players, typically only a few milliseconds at most. The resulting effect can be described as a “whoosh”
sound that is similar to the sound of a jet plane passing by in the sky. In fact, the comparison is very
accurate – a passing jet sounds the way it does because the sound waves arriving directly at your
ears and the reflected waves bouncing off the ground are delayed slightly from each other, and this
delay time changes as the jet changes its position relative to you.
In technical terms, a flanger sweeps uniformly spaced notch filters through the frequency spectrum
of an input signal.
Over the years, as technology has permitted, methods for producing flanger effects have become
possible without the need for big, bulky tape players. The Mercury packs all of the power of a
traditional tape flanger into a compact package, and brings some new technology to the table as well.
The amount of delay in the flanger effect needs to be changed over time to sweep the notches across
the spectrum. In order to do this, a low frequency oscillator (also known as an LFO) is used to control
the delay time, as well as several other parameters. This is illustrated by the following graph:
The blue line in the graph is known as the LFO. It changes the amount of delay over time.
The frequency (a.k.a. “rate” or “speed”) of the LFO can be increased to get a more rapid change in
the delay time, as shown in this graph:
DELAY TIME
TIME