Chorus Effect

The chorus effect occurs when various individual sounds, with similar pitch and timbre, play at the same time. It mimics pitch and timing variations, so an audience can perceive a single instrument source sound as if there were multiple instruments playing in unison. This effect is very common when a group of singers or violinists, with variations regarding pitch and timing, play simultaneously. These practically imperceptible variations are responsible for producing unique sounds generated by large choirs and string sections of an orchestra.

Chorus Effect: the History 

The Hammond organs were the first instruments to use the chorus effect. Decades later, some professional recording studios used the Automatic Double Tracking effect (ADT). The operation of this effect was quite simple. It used a copy of a recording, with a slight delay, and engineers played it over the original signal. This effect gained popularity when the Beatles started using it for their recordings in Abbey Road Studios. You can achieve a similar effect by combining synths and organs. 

The unique chorus sound that we know today became famous around the 1970s with the appearance of the first stand-alone chorus pedal: the Boss-CE1. Nowadays, the chorus effect is a common guitar pedal effect. Musicians employ it mainly on the acoustic guitar, the electric piano, and the clavinet. When used on strings and synthesizer pads, the chorus effect creates a rich complex sound. In addition, you can choose this effect to broaden a stereo image.

Where to Find It

You can find the chorus effects in both analog and digital realm. Modern chorus software effects include a wide range of parameters, such as LFO speed and depth. Also, some plugins include control of the wet/dry mix. When completely wet, the pitch modulation of a chorus effect mimics a vibrato. Moreover, these effects have several variations. Some examples are mono, stereo, and surround chorus, as well as single and multi-voice chorus and some other advanced types with complex LFOs.