Flanging

Flanging is a time-based audio effect that occurs when two identical signals are mixed together, but with one signal time-delayed by a small and gradually changing amount, usually smaller than 20 milliseconds. This produces a swept comb filter effect: peaks and notches are produced in the resultant frequency spectrum, related to each other in a linear harmonic series. Varying the time delay causes these to sweep up and down the frequency spectrum.

Part of the output signal is usually fed back to the input (a 're-circulating delay line'), producing a resonance effect which further enhances the intensity of the peaks and troughs. The phase of the fed-back signal is sometimes inverted, producing another variation on the flanging sound.

A "flanger" is a device dedicated to creating this sound effect.

("Flange" was one of many words used out of context on the show to confuse/amuse the audience).

American music industry veterans David S. Gold and Stan Ross, founders of the renowned Gold Star Studios in Hollywood, claim that they made the first commercial recording to feature the technique — the single "The Big Hurt" by Miss Toni Fisher which was recorded at Gold Star in late 1959 and which became a national US hit in early 1960, rising to #3 in the Billboard chart. Also, flanging is heard in the opening of The Ventures' 1962 cover version of The Tornadoes hit "Telstar", in the context of a simulated rocket launch sound effect.

The first use of flanging effect in stereo is credited to producer Eddie Kramer who used the effect in the coda of Jimi Hendrix's song "Bold as Love" (1967). Kramer admitted in an 1990s interview that he read BBC Radiophonic Workshop technical journals for ideas and circuit diagrams.

In 1969, the record producer for The Litter, Warren Kendrick, devised a method to precisely control the flanging effect by placing two 15 IPS stereo Ampex tape recorders side-by-side.Diagram by Warren Kendrick - ‘K-Tel Reissue CD 10002 (1991)’] The take-up reel of recorder A and supply reel of recorder B were disabled, as were channel 2 of recorder A, channel 1 of recorder B and the erase head of recorder B. The tape was fed, left to right, across BOTH recorders and the identical signal was recorded on both channels of the tape; the signals were displaced approximately 18 inches from each other. During the recording, a screwdriver was wedged between the tape recorders to make the tape run "uphill" and "downhill." The same configuration was employed during the playback/ mixdown to a third recorder. The screwdriver was moved back and forth to cause the two signals to diverge, then converge. The latter technique permits zero point flanging; i.e., the lagging signal crosses over the leading signal and the signals change places.

Artificial Flanging

In the 1970s, advances in solid state electronics made the flanging effect possible using integrated circuit technology. Solid state flanging devices fall into two categories: analog and digital. The flanging effect in most newer digital flangers relies on DSP technology. Flanging can also be accomplished using computer software.

Note that the original tape-flanging effect sounds a little different from the later electronic and software re-creations. Not only is the tape-flanging signal time-delayed, but the response characteristics at different frequencies of the magnetic tape and tape heads inevitably introduced some phase shifts into the signals as well. Thus, whilst the peaks and troughs of the comb filter are more-or-less in a linear harmonic series, there is a significant amount of non-linear behaviour too, causing the timbre of tape-flanging to sound more like a combination of what came to be known as flanging and phasing.

"Through-Zero" or "Zero-Point" Flanging

The other difference is that the common electronic flanging effect is accomplished by mixing one delayed signal with the original undelayed signal. As such, one of the signals is unaltered in time, while the other signal is alternately delayed behind the original and then speeded back up to produce the effect. In analog tape flanging, first one signal is delayed (by slowing down one of the tape machines by pressing the flange), then the other signal is slowed down (by pressing the flange of the "other" tape machine) to "catch up" with the delayed one, "passing" through the point of perfect time alignment (the "zero point") and continuing to slow down, thus becoming itself the delayed signal. This effect is sonically much more dramatic than simple one-track flanging.Fact|date=July 2008 Zero-point flanging (also known as "through-zero flanging") can't be easily replicated by simple digital delay circuits because both signals are progressively slowed down one after the other and before long the delay time limits of the circuits are reached.

The zero-point "through" effect is clearly audible at the end of the "Itchykoo Park" sample clip above.

Zero-point flanging can be produced by some digital workstation plug-ins, or by manipulating two digital workstation tracks in time using various programming methods.

"Barber-Pole" Flanging

Also known as "infinite flanging", this sonic illusion is similar to the Shepard tone effect. The sweep of the flanged sound seems to move in only one direction ("up" or "down") infinitely, instead of sweeping back-and-forth. While Shepard tones are created by generating a cascade of tones, fading in and out while sweeping the pitch either up or down, barber-pole flanging uses a cascade of multiple delay lines, fading each one in to the mix and fading it out as it sweeps to the delay time limit. The effect is available on various hardware and software effect systems.which

Notes

See also

* List of recordings with a prominent flanging effect
* Comb filter

External links

* http://www.harmony-central.com/Effects/Articles/Flanging/
* [http://www.shredaholic.com/mxrflanger.html MXR Flanger] - information on building a Flanger effect box for the electric guitar
* [http://groups.google.com/group/rec.audio.pro/msg/c7055c32f0ab1992?hl=en& Explanation of analog zero-point flanging from Usenet's rec.audio.pro forum]