Flanging is a time delay effect using very short time delays mixed together with the input (dry) signal. This creates a series of peaks and notches in the signal's response through the audible spectrum. When the time delay is varied, the peaks and notches move or "sweep." The FL9 Flanger features an extremely quiet time delay section creating an unusually noise-free flange. The sweep and width may be changed as well as overall time delay. This allows the artist to center the flanging action in a particular part of the sound. Flange intensity may be adjusted with the feedback control. The FL9 Flanger provides quality and flexibility that defies comparison. - FL9 description in 1984 Ibanez Sound Effects catalog.