Chorus Effects: A Brief Guide

This article is a brief guide to chorus effects. It explains what Chorus is. What In-and Out Puts they have? What are the typical controls and applications of a Chorus effect? What variations are there among the various Chorus effects?
The article is not a guide to the various Chorus pedals which exist. Any brands mentioned in this article only serves as a example for a particular sound.

Chorus is a form of Delay optimized for a specific function. A typical guitar signal will sound fuller and more animated once processed through a Chorus effect compared to the signal being without any form of processing.

Delay times of 10 to 25 mS will start to produce Chorus sounds. Some Chorus brands may even give you a shorter delay range to alter the colour and sound of the particular unit.
A delay range of 25 mS and anywhere above will give you Slapback Echo and other forms of Echo and Spacial effects.

The first Chorus effects for Musical Instruments started to appear in the mid-to late 1970s. Most of them used the “Bucket-Brigade Device” (BBD) technology. Later on, in the 1980s, as digital technology became more available and less expansive, more Chorus units started to use the newer, digital technology. In general, digital Chorus effects tend to be brighter and less noisy compared to the earlier BBD examples.

In-and Out Puts:
Most Chorus effects will have one Input and one-or two Outputs: One for a Mono output, this output combines the straight signal with the Chorused sound. The second Output may contain the straight signal or a out-of phase ( inverted) sound. The inverted Output will make your sound a little duller or brighter. Using both outputs will make the Chorus sound fuller and Spacial.

Typical Controls:
Speed (or Rate): This control will let you vary the speed of the modulation. It will give you the sense of your sound speeding up or slowing down.

Depth (or Width): This control will let you vary the depth of the modulation. Increasing the depth will make the Chorus appear fuller in sound.

Effect Level: This control will let you dial in more-or less of the given Chorus effect.

Delay Time: This control will let you fine-tune the range of the Delay for the Chorus.

EQ: This control will let you choose the band range from low to high frequency range. Basically it will make your Chorus sound duller or brighter depending on the setting of this control.

Input: This control will allow you to set the input level of the overall volume level. Turn it all the way down and you will have no sound! Open up the control fully and you may get unwanted distortion.
Input controls often come with a combined overload Led. It is a handy way to tell you what your optimum input signal should be.

Some Chorus units may come with a switch which lets you toggle between Vibrato and Chorus, or Vibrato and Flange. There may even be controls to vary the Delay, Speed and Depth of the Vibrato.

Typical Applications:

Vibrato: Increase depth and delay time to create a extreme sound. Doing the opposite will give you a gentler and less extreme Vibrato sound.

Rotating Speaker Simulation (Leslie Effect): Increase the speed and depth. Use two Chorus effects to fully exploit this sound:
Set up one unit for a slow speed while the other one is set up for a faster speed. Connect both units to a A/B box, toggle between the two units to experience your sound slowing down and speeding up again, just as you would when using a Leslie Cabinet.

Gentle Chorus: Speed and depth are both half way up to create a less dry guitar sound.

Variations in Chorus Sound:

The Boss family came out of the CE-1 with its fine and sophisticated sound. This sound has become very popular over time. It is also a sound which has been copied by many different type of brands.

Electro Harmonix produced some Chorus pedals which contain a rougher, more primitive and therefore unique sound sound. Examples of this are the Clone Theory and later version of the Memory Man.
Between those two opposites lie many subtle variations. My examples of the Boss-and Electro-Harmonix type of sound only serve as a guide for your ears. As you research the various Chorus types around also check out some of the sounds as found on Pitch Shifters. Some of these can give you Chorus sounds which you cannot obtain using standard, basic Chorus units.

There are no good and bad Chorus sounds: some you may find more inspiring compared to others. One particular unit may be better for a certain application compared to another one. Being aware of some of those aspects will help with your choose what kind of Chorus is good for you.

I will create more articles about Delays and Flangers in the near future.

Hope to see you soon again,
Eddie