What is Flanger and how to use it

Flanging is an audio process that combines two copies of the same signal , with the second delayed slightly, to produce a swirling effect. The process originated before digital effect boxes and computer editing were available. The effect, invented in the early 1950s by Les Paul and later used by artists such as Jimi Hendrix and The Beatles, was originally created using two tape recorders.

Here's how the nondigital process worked: While the original sound was being played from Tape Recorder #1, a second copy of the same audio material was played back from Tape Recorder #2.
This process alone creates a hollow sound caused by the slight irregularities in the phase relationship of the audio waveforms. To get the flanging effect, the speed of the second recording was altered slightly. This was done most often by pressing a finger lightly on the tape reel's "flange", the large metal circle that surrounds and contains the tape on its hub. This created a time delay in addition to the phase differences, making the effect more pronounced.

Today, digital simulations of the process have replaced the flanging effect that was created using reel-to-reel tape recorders. The basic concept remains the same. The software or hardware device delays a copy of the source audio, but instead uses a low frequency oscillator (LFO) to vary the speed of the copy's playback. (The oscillator moves in the range of 1-20 cycles per seconds to get the effect.) Feeding the processed signal back into the device to be processed again can get a more intense effect.

Guitarist Les Paul invented flanging. He and Mary Ford first made it popular in the early 1950s. Les Paul also invented the solid body electric guitar and many sound techiques in use today. The first completely digital electronic flanging unit was the Delta Lab Research CompuEffectron, introduced in the 1970s.

A typical flanger pedal has four knobs, and three of them—speed (or rate), width (range or depth), and manual—are related to the LFO (see the flanger pedal block diagram at right).

So what’s up with the fourth knob? The regen (intensity or enhance) knob feeds some of the delay output back into the input. This control may have originally been added to compensate for the fact that the studio tape flanger trick could produce some extreme sounds by speeding up the flanged deck ahead of the original signal (creating what’s sometimes called a “negative delay”), and then slowing it down to pass through zero delay time, whereas the pedal can only delay the signal by positive amounts. The regen knob doesn’t produce this particular sound, but it intensifies the flanging effect and adds a bunch of sonic possibilities. Later pedals obtained the “through-zero” effect of actual tape reels by adding a short delay in line with the input signal, but we’ll save that for another discussion.

The typical delay range of a flanger is about 0.5–10 ms. These delay times are heard as filter effects at the shorter end of the range (because frequency rises as delay times get shorter), and pitch effects (chorusing) at the longer times when combined with the input signal. This is the nature of comb filtering, which is what happens when a delayed version of a signal is added to itself. The three LFO controls determine how fast (speed), how much (width), and in what delay region (manual) the modulation occurs.

From a technical standpoint, the width knob sets the LFO amplitude, and the manual knob sets the LFO offset. Note that, as the width is increased, the manual control becomes less effective. When the width is at maximum, then the entire region of delay times is being used, so the manual control doesn’t do anything. At the other extreme— with width at zero—there is no oscillation, just a fixed delay time that is adjusted by the manual control, which allows a physical sweep of the entire delay range.

Clean tone and Flanger

If you are as old as I am, it should propell you right back to the early 80s and “new wave” bands such as The Cure or pop bands such as The Police. Flanging (and also Chorus) gave an ethereal quality to arpeggios and chords which suited their music perfectly. Both slow and fast rates are interesting in that respect. Note that it also suits funk rhythm licks.

Distortion and Flanger: Before or After the Distortion?

Eddie Van Halen used a phaser a lot but little is known that he also used a flanger to create some of his best tones. “Unchained” is probably his most recognizable Flanger tone. Queen’s Guitarist Brian May is also a big flanger fan, listen to “Keep Yourself Alive” for a fine example of tape flanging.

The Flanger effect is usually placed after overdrives and distortions in the chain but it can also be interesting to place it before, which is something that Prince does for instance.

With this information in mind, we can formulate some general ideas about how to craft particular sounds. Below are some starting points to help you explore the diverse sounds that a flanger is capable of. To add more variables into the mix, the LFO sweep shapes can be linear or logarithmic, depending on the flanger—and some flangers allow polarity changes on the feedback. Luckily, the same basic principles still apply.

Chorus-like sounds

A chorus doesn’t have any regeneration, so set the regen to minimum. Set manual to its lowest setting for long delay times. Keep the width low, but not at minimum. (Remember, if the width is at minimum, the LFO is not oscillating—hence, there will be no modulation sounds.) If the effect is too pitchy, try reducing the width or the speed.

Jet flyby

Set a moderate speed. Turn the manual to halfway and crank up regen. Set width to the desired sweep range, then adjust manual to dial in the sweep region to taste.

Auto-wah

Set a reasonably fast speed and keep width low to stay in a limited region of delay times. Add some regen to enhance the filter resonance. Then, experiment with the manual control to tune the auto-wah frequencies.

Classic flanger sweep

A moderate speed with maximum width allows the delay line to sweep from the lowest to highest delay times, thus showcasing the underlying character of the flanger. Add some regen to taste.

Resonant filter

Set width to zero to “freeze” the LFO. Add a generous amount of regen to increase the resonance, and turn the manual knob to dial in the filter frequency.

Freq out

Set all controls to maximum. (As we mentioned earlier, with width at maximum, the position of the manual control is irrelevant.)

With this knowledge and a little practice, you should now be able to use your flanger to dial in a lot of different sounds with authority. And don’t forget the value of experimenting—turn knobs, play guitar, and have fun!