The Chorus

The chorus is an effect that serves to notably enrich the sound, doubling the signal and giving the sensation of hearing two or more guitars playing the same part (to play in unison). Lets look at an example of how stereo chorus works.
The input signal is divided in two: the first signal (generally called dry, which is the original sound) is sent to output 1 and is an output signal identical to the input. The second signal coming out of output 2 is slightly out of tune and delayed by about 20ms (milliseconds). This delay is not considered a true delay (which would give a fixed and constant repetition of 20ms), because it will continue to vary with a response margin of +/- 5ms. The processed sound will cyclically delay: first 15ms, then 20, 25, 20, 15, 20 etc. Obviously, as we will see, you can have other settings. The human ear won't hear the false note but instead a much broader sound. A mono chorus, where only one output mixes the two signals, produces practically the same sound; two stereo speakers are better than one mono, and for this reason the stereo chorus is acoustically better.
I mentioned before that the chorus is similar to two guitars that play the same part. The question that comes to mind is this: if the chorus is slightly off key, how is it possible that two guitars played in unison (in tune) are slightly off key? The answer is simple: man is not a machine and it is virtually impossible that two guitarists play the same part the same way. A difference that you wouldn't notice if listening to the first giutar and then the other, but when combined together would give the typical chorus effect.
This effect can also be obtained while recording. Try to record one part on a track, then record that same part on another track. Listening to the mix of the two tracks, you will surely have a bigger, more full-bodied sound. In this case we will also have a chorus effect. Lets try to understand why.

• No matter how much you try, it is rhythmically impossible to play the two pieces, because the first piece would always be early or late by a few milliseconds with respect to the second. Remember that the perfection of the execution allows this delay, which is really very minimal.
• The intonation. Strumming the pick harder or softer, or the different pressure of the finger on the chord would change the intonation of the note. This is why the guitar is always played slightly off key, even if the human ear can't distinguish it.

• Pre-delay. Adjusts the time interval from the moment in which the note is played to the moment in which the effect intervenes. This is generally expressed in milliseconds. A higher value will make the chorus intervene later with respect to the played notes, while a 0 value will allow the effect to start instantly.
• Depth. Adjusts the depth of the effect. A higher value corresponds to deeper undulations. It is practically the intensity of the chorus.
• Rate. Adjusts the cycle of the effect, which is the speed of the phase or rhythmic off note. A setting of 0 is very slow (not even one cycle/second), and 10 is very fast (rarely used).
• Feedback. Refers to the return of a portion of the sound with effect to the input of that same effect. You therefore adjust the quantity of chorus that returns to the input to obtain distinct sounds.
• Level. Adjusts the mixing level of the chorus with the original sound. A higher value gives more effect.

These controls are present in rack equipment and also in some sophisticated pedals. With normal pedals there is usually only the depth and rate controls.
The chorus effect can also be obtained using the Pitch Transposer, which is contained in many multi-effect units. To obtain the chorus, you need to have a stereo amplifier and to adjust it as follows:
CHANNEL A (left) Pitch 0, fine -5 (even up to -10), delay from 0 to 10-50ms.
CHANNEL B (right) Pitch 0, fine +5 (up to +10), delay from 0 to 10-50ms.
The pitch creates a duplicate of the note for every channel. The procedure is done using the fine. The result is very interesting, even if all machines are not able to do it very well. The purpose of the delay is to delay the response of the chorus, creating better environmental sound. A delay of about 10-15ms can be set for the rhythmics and the fast phrasings, while rhythmics, arpeggios or slow solos can be set to about 80 ms.
Whatever system you use for obtaining chorus, you need to be careful to not misuse it, because a very intense effect would cause the lose of dynamics where not all notes can be heard.
In the chain of effects, the chorus is placed before the delay and the reverb and after the distorter, the compressor and the equalizer.




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