Chorus, Phasing, Flanging and Wah

Chorus has now become a common effect. As with most effects it was initially used by guitar players wanting to add complexity to the sound of the instrument.

As its name states, chorusing gives you the possibility to give a chorus like feeling to the instrument’s sound.

The effect makes a copy of the original signal slightly delaying it (between 10 and 25 ms) and adding a small pitch shift (without making it sound out of tune).

It actually works as a group of violin players playing the same note: they will not be perfectly synchronized and the sound of the violins will never be exactly the same.

So when you’re using the chorus effect on your violin you are actually creating another sound (the equivalent of a second violin playing the same notes as you are) and combining the two sounds.

The result will be a warm, more complex sound. Chorus effect units usually allow you to set the intensity of the added sounds as well as the delay of each sound.

The chorus effect is mainly used to enrich the sound. One of the secondary effects is that chorus de-localizes the sound, making it impossible to track its source.

If, however, you want the sound of an instrument to stand out, it should be rather dry (in terms of reverb).

Thus, while chorusing has the advantage of make your instrument produce richer sounds, it also has the disadvantage of making it less dramatic and weaker in terms of melodic intensity.


Phasing uses another concept to process the sound. As in the case of chorusing the original signal is split in two: one straight signal that does not suffer any changes and another that is diverted via a phase-shift network.

This network is controlled by a low-frequency oscillator which constantly changes the tone of the processed sound.

Combining the two sounds results in a cancellation process (when the phase-shifted signal path is out of phase with the straight signal path) which will create a notch in the frequency response of the output.

As with the chorus, the disadvantage of using the phasing effect is that the instrument’s sound will be heard somewhere in the back of the mix.

Thus, it is recommended that you use this effect only in sparse musical arrangements that provide plenty of space for the rich sound of phasing. This allows you to mix the sound higher and bringing it to the front.


Flanging brings the best out of phasing and chorus combining them to give a brilliant effect. As with phasing, two signals are used, one straight and one processed.

The difference between the two effects is that flanging also adds a delay to the processed sound (several milliseconds) and also modulates it.

The concept is the same as in chorus, delaying the processed sound and then combining it with the original signal.

However, chorus uses longer delay times. While the simple flanging effect uses the same technology as the chorus for delaying the sound, the more complex flangers feed a part of the delayed output signal back to the input.


The wah effect is achieved by using a filter that exhibits a resonant peak just at its lowpass rolloff frequency.

It is called wah as the resulting sound strongly resembles the human voice making a ‘waaaaaah’ sound. The wah effect is controlled by a foot pedal which has to be moved in time with the music.

However, there is the so-called auto-wah which has the same effect with the only difference that the frequencies are controlled automatically. Of course, this does not give you the same freedom as in the case of the pedal.

Chorus, phasing, flanging and wah are very common effects, but you don’t always achieve the sound you were looking for. Thus, choosing the best effects for you can be a tricky job.