The effect of flanging originated in a studio that was trying to double a vocal track for The Beatles. The technique used included two tape machines that had the exact same vocal track recorded on both of them. When played back to be recorded onto a third tape machine, the slight differences between the motor speed of the first two machines created a flanging or comb filter effect. This is different than a chorus or phase effect in that it is additive and subtle because the delay of one tape machine in relation to the other is usually fewer than 20 milliseconds.
In the early days of development, this effect was used on the final output of a mix and was prominent over the entire mix. Later, this effect of flanging was used on individual instruments or vocal tracks alone. Before the electronic versions of this effect had been developed, an audio engineer would place his finger on one of of the tape flange guides to slightly slow down one tape machine in relation to the other tape machine. To reverse the phase and direction of the flange effect, the audio engineer would place his finger on the other tape machine’s guide flange, and it is believed that this is where the tern “flanger” originated. This comb filtering effect became widely used in early 70s’ styles of popular music.
Today, the flanger effect is a lot easier to create than back then and can be found in the form of a portable stomp box configuration or included in a rack-mounted effect system that includes other effects as well. This flanging effect can widen and enhance an otherwise dull and lifeless audio track and has several different control features, such as frequency modulation, speed, depth, range, volume and output mix.
Although the controls are similar to chorus and phase effects, the resulting output is considerably different than these other commonly used audio effects and can enhance the signal of most studio instruments and vocal performances. Today, the effect is created electronically by the use of solid state circuits or with the use of software algorithms contained in digital audio workstations VST plug-in set.
This effect can create several different output signals, and it can be mixed with an original signal to create new effects. But the main use is a doubling effect that is now created in the studio by playing exactly the same instrument part or performing exactly the same vocal part twice in an effort to smooth out the resulting final mix. Flange effects are still used but are considered to be less useful that multiple tracks of repeated performances by an musician or singer.