Koogo Flanger

The Koogo Flanger is a flanger pedal from Koogo. Like every flanger, it belongs to the modulation family of effects, the group that also includes chorus, phaser and vibrato pedals. What sets a flanger apart is the sound it produces: the sweeping, whooshing jet-engine effect heard on countless records, from subtle movement under chords to the full "airplane taking off" sweep.

What a flanger does

Flanging is a modulation effect created by mixing two identical audio signals, applying a slight delay to one signal, and slightly and continuously varying that delay over time¹. EarthQuaker Devices describes the result plainly: two identical signals are mixed together, with one playing at a slightly slower speed, creating a swooshing effect similar to the sound of a jet engine². Because the delayed copy keeps sliding in and out of alignment with the original, certain frequencies cancel while others reinforce, and that moving pattern of peaks and notches is what you hear as the sweep.

The character of the sweep depends on how the pedal is set. Drolo's documentation for its own flanger describes the range available across the effect as a whole:

Drolo FX manual³

The same manual notes that on a delay-length control, counterclockwise settings give the shortest delay times and more airplane-like conventional flanger sounds, while increasing the delay brings in very short repeats³. Feedback is the other key ingredient: as Jon Cusack of Cusack Music puts it, a flanger uses a much shorter delay with feedback, giving the jet-engine sweep⁴.

How a flanger works, step by step

Flangers work on time delay, taking two signals and mixing them, and playing one signal back at a slower speed with an LFO (a low-frequency oscillator) to modulate the timing of the delay, giving a sweeping, whooshing effect⁵. In order:

1. Your guitar signal is split into two identical copies.
2. One copy is delayed by a very short, constantly changing amount of time, driven by the LFO.
3. The two copies are mixed back together, so their frequencies reinforce and cancel as the delay shifts.
4. Feedback routes some of the delayed signal back through, intensifying the sweep into the familiar jet-engine whoosh⁵⁴.

Where flanging came from

Flangers originated in the studio by manipulating tape machines, producing their jet-like sweep⁶. The story goes back to early experiments with audio signals on magnetic tape, including two reel-to-reel machines and pressing on the reels; engineers would change the position of the machines to make them run slower or faster⁷. The effect only later shrank into the pedal format players use today.

One famous example of the effect on record: Rush uses flanging in "The Spirit of Radio", where it helps the opening arpeggio feel like it is building even though it is the same part repeating⁷.

How a flanger differs from chorus and phaser

The modulation family all work by delaying or shifting a copy of your signal, and how much the signal is delayed or its frequencies altered leads to the different effects: chorus, phase, and echoes⁷. The practical distinction for a player choosing between them:

Companies like Strymon, TC Electronic, Electro-Harmonix, Universal Audio, and many more all make their own versions of modulation pedals with flanging⁷, so a player comparing a budget unit like the Koogo against established makers has a wide field to choose from.