What is Chorus?
In music, a chorus is a group of singers, like a choir. Other times, the term chorus is used to describe the part of a song where everyone sings together in between the verses. What is the theme here? Singing together.
What's Unique About a Singing Chorus?
When one singer sings alone, you hear a single note. But, when a group of singers sing together, something interesting happens. Even if all of the singers sing the exact same note, they won't all sing that same note perfectly in-tune. Some will be spot-on, some will sing slightly sharp (above the pitch), and others slightly flat (below the pitch). This creates a “wider” pitch, or you may imagine it slightly “blurring” the exact pitch.
A choir's singers will also have slight rhythmic differences beginning notes at different times. The “blurry” pitch and rhythm makes it sound more lush, and is what gives a choir its unique sound.
Instruments with Chorus
Some instruments create the chorus effect on their own. Most of the hammers of a piano, for instance, strike three strings tuned almost to the exact same pitch.
A 12-string guitar works similarly. Each of the guitar's six strings is doubled with a string tuned an octave higher. They're never perfectly in tune, and that adds to the lush sound of a 12-string guitar.
Mandolins have doubled strings as well, but tuned to the same octave. And, accordions have multiple reeds producing a chorus sound.
The Chorus Effect
The chorus effect isn't only generated by singers or instruments; we can produce it electronically with a chorus pedal, or digitally with a chorus plugin, and apply it to any sound source or instrument we want.
How Does the Chorus Effect Work?
The chorus effect takes the source sound like your bass signal, copies it, and slightly alters the timing using a delay much like the flanger effect did. When the new sound is combined with the original, the “singing together” effect is produced.
The difference between the flanger effect and the chorus effect is the length of the delay. A flanger uses a delay time of less than 10 milliseconds. Chorus uses between 10 to 20 ms. With the longer delay time, something interesting happens—the pitch is slighlty altered, or shifted.
The Doppler Effect
When the same audio waves are repeated and slow down, the pitch drops. If they speed up, they rise in pitch. This is due to what's known as the Doppler Effect.
The Doppler effect is what you hear when an ambulance goes past you. As the ambulance approaches, the pitch goes up; as the ambulance moves away from you, the pitch drops. That's due to the timing of the sound waves reaching you. The delay time of the chorus effect takes advantage of this audio phenomenon.
The choir-like sound of the chorus effect is a result of the slight pitch-shifting of the audio signal and the slight variations of start times of the delayed audio signal.
Chorus on Bass Guitar
Chorus is one of the more popular effects for bass guitar. Some bass amps even have chorus built-in. There are also a number of chorus pedals from which bassists may chose.
When used tastefully, chorus can add a very melodic presence to a bassline. Using chorus on bass guitar can make the bassline sound like it is singing. Of course, it's the playing of the bassline that really makes it melodic (for that, see the bass lessons), but the chorus effect can enhance it.
Chorus is most pronounced on longer notes, but it can work on any sort of bassline.
Once again, here's my example bassline without the chorus effect:
And here is the same bassline with the chorus effect:
Chorus on Slap Bass
For a time in the 1980s, using chorus on slap bass was hugely popular. Anytime I hear someone slapping with chorus on, it immediately takes me back to the 1980s! This is always a danger with effects and technology. It can really date something. Take care to not use the same effect on everything, and don't use too much. Otherwise you'll be locked into that sound, and you may date your recordings or songs. Think how funny that autotune effect on vocals will sound in 20 years!
Here's a slap bassline with the chorus effect:
Too Much Chorus on Bass
You must be careful with pitch-altering effects on a crucial instrument like the bass guitar. Since one main role of the bass is to define the harmony, changing the pitch too much can get in the way or cause problems for the band as a whole. As with most effects on bass, a little goes a long way.
Examples of Basslines with Chorus
Let's listen to a few examples of the chorus effect used on bass guitar.
Sweet Child of Mine
You can hear the chorus effect clearly on Duff McKagan's classic opening melodic bassline of Sweet Child of Mine.
Boogie Oogie Oogie
Janice Marie Johnson's intro on Boogie Oogie Oogie also uses the chorus effect and backs it off afterwards.
Save a Prayer
In this 1980s pop ballad, John Taylor plays a beautiful bassline using the chorus effect all the way through.
In the next article, we'll look at common chorus settings and controls.
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