What’s a Chorus Effect?

Effects: what are they and what do musicians actually do with them? When it comes to music, effects are everywhere, so if you’re struggling to see the wood for the trees, this blog has been written to offer a guide for anyone taking their first steps into the more technology-based side of music. Here, we’ll cover chorus and what you can do with it, but we’ll also look at concepts related to creating ensembles.

The Fat Sound of Ensembles
Chorus
The Technique
The Gear
Alternatives to Chorus
Authentic Ensemble Sound
Why Not Just Use a Chorus Effect?
“But my Synthesizer Sounds Great Through a Chorus!”
Sound Synthesis
See also…

The Fat Sound of Ensembles

Anyone who’s been to see a live symphony orchestra will have noticed the small army of strings on the stage. Even the average orchestra will include around sixty! The primary reason for this is volume. One violin on its own won’t sound all that loud at all, especially not when you’re pitting it against the force of brass and woodwind instruments. So, by having a load of violins playing exactly the same part, the volume of the violins is brought into balance with the rest of the orchestra.

This method also applied to the alto violins, the cellos and the double basses. As you go down the list, each of these string instruments gets bigger and bigger, meaning that each instrument is a bit louder than the next, which is why you have a mass of violinists next to just a few double bassists. The ratio of strings is often 14:12:10:8:6, 16:14:12:10:8 or 14:14:12:10:8 (and can be in a range of different configurations). The first configuration includes 14 first violins, 12 second violins, 10 alto violins, 8 cellos and 6 double basses.

Besides bigger volume, this ‘bulking out’ also creates an interesting side effect – a pretty nice side effect in fact. Because the violin and other bowed string instruments don’t have any frets (like most guitars have) slight pitch fluctuations occur. After all, even if you shift a finger by just a millimetre along the string, you’re changing the length of the string, and therefore the pitch. Because of this, the vibrato of one violinist is never going to sound exactly the same as the next either. Every violinist will play it slightly differently, especially if the score dictates that it should be played aggressively. The result? Fourteen first violinists producing a subtly varied sound, which melded together sounds fat, warm and lush.

This concept actually works for most musical instruments. With brass instruments like french horns, trumpets and trombones, the effect is really clear and much-loved. This effect isn’t just caused by the variation in sound and intonation, but by the fact that each musician has their own physical position in the orchestra. Sound in general is partly built by the acoustics of the space the sound is made in. So, if the trumpeters were to move to another spot, this would cause a shift in the movement of air caused by sound waves and how those waves bounce off the walls, which very subtly changed the timbre.

Ok. So, leaving the orchestral theory to one side for a minute…

Chorus

While orchestras are brilliant things, not everyone can fit one in their back bedroom, so there must be a way to simulate the same effect without having to hire a concert hall and fill it with a full orchestra. The solution is ‘chorus’, a name which comes close to ‘chor’ or ‘choir’, since the way choirs are made up works in exactly the same way as the orchestral string section described in our example above – the voice and technique of every vocalist has its own unique intonation and timbre – resulting in a lush and full whole.

The Technique

In the previous edition, we talked about delay, and mentioned that delay and chorus have a lot in common. So you know exactly what we mean when we say things like tape-head and buffer, it might be worth reading back over the blog.

Like a delay effect, a chorus effect also involves buffers, which temporarily capture the original sound. The sound captured by the buffer is then read by a ‘tape-head’ that can move at a variable speed, which results in a kind of vibrato that sounds like it’s being played back by a second musician. If a chorus effect has multiple buffers (just like several delay stages) it’s able to simulate a larger ensemble of musicians. When all of these delay stages are staggered in terms of their physical position and every stage is read by a buffer set to a different vibrato speed and depth, then it comes close to the sonic effect of the multiple violinists that make up a string section – in other words, it comes close to the sound of an ensemble.

The Gear

As mentioned in our blog about delay, the technology that lies behind this effect isn’t all that complex, and because the tech is so simple, you could easily pick up a chorus pedal for the price of a DVD – which Fazley proves with the CHR-01 pedal. Even big, multi-effects units will include a chorus, and most DAW recording software will always come with an effects package with at least one delay, reverb and chorus.

Alternatives to Chorus

How good a chorus sounds and how good the effect of the algorithm it uses is something that does differ from the sound of a real ensemble of musicians. The effect only has one sound source to work with, and because of the unmoving vibrato speed, some chorus effects can have a static character to them. An effect that uses multiple chorus stages (so, delay stages) can mask this slightly static feel, but most of the time, a chorus effect pedal just won’t be that extensive. To gain a good ensemble-like sound using musical instruments and equipment, a different approach is needed.

Authentic Ensemble Sound

The most logical and effective approach is, of course, to just put together a real ensemble. Anyone with a microphone and just one djembe, for example, is able to create the illusion of a djembe ensemble by simply repeatedly recording and layering the same beat. To really get the effect right, the trick is to place the microphone in a different position for every recording. This simulates the spacial aspect of an ensemble, where multiple musicians are sitting in different spots. All those small variations in location as well as the variations in timing, combine to result in a big sound. To really get that wide ensemble sound, it’s also recommended to use a stereo microphone so you can really capture the acoustic placement.

With an instrument like the trumpet, this recording method can result in a really great effect. Simply by recording the same part four times you can immediately create the illusion of a trumpet ensemble. However, because of the embouchure and lip tension needed to play a trumpet, the musician has a quality of control over the sound that’s unique to them. As such, there’s no getting away from the fact that four different trumpeters playing together will create a different overall sound than the same trumpeter playing the same part four times over. This doesn’t just sit in the embouchure of every musician, but in the instrument itself (including the kind of mouthpiece being used – which is a really personal choice when it comes to playing the trumpet).

Naturally, the same applies to any instrument where the way the musician physically moves has a direct influence on the sound. Even the size of your hands will have a subtle effect on the sound of a drum. The physical movement of the musician on an instrument like a piano or harpsichord won’t have such a noticeable effect in the same way, since we’re talking about a mechanism that’s triggered to strike internal strings. So there’s less sense in stacking these kinds of instruments to try to create an ensemble.

With a guitar, it’s actually a bit easier to fabricate a broad ensemble-like sound. It’s actually a common recording trick referred to as double-tracking, where the guitarist records the same part twice and when it comes to mixing, one recording is panned to the right and other is panned to the left of the stereo image to create a beautifully broad guitar sound.

Why Not Just Use a Chorus Effect?

Even with the best chorus effect you can lay your hands on, you wouldn’t be able to turn the sound of a single violin into the lush and enveloping sound of a violin ensemble. Multiple factors are stacked against the humble chorus pedal, a few of which we’ve already covered: the subtle variations in pitch, the unique way that each musician performs a vibrato, the subtle differences in the sound of each individual instrument and the acoustic placement of each musician in a physical space. The musician’s overall performance, including their timing, might have an even greater influence. When a musician is transitioning from one note to the next there might be a little glide in between, a really audible glide or no glide at all. Maybe the musician hits the note perfect, or maybe they’re just off and need to quickly correct it. All of these tiny details go into building the sound that results. So, no matter how good a chorus algorithm is, it will never be much more than basic maths, so so far, unfortunately the software still can’t truly compete with a living, breathing ensemble.

“But my Synthesizer Sounds Great Through a Chorus!”

True, but when it comes to synthesizers, chorus is pretty much intertwined with the concept, and even then, it only really works when applied to specific sounds. The synthetic sound of something like a sawtooth wave and a chorus simply sounds right, and also, we already know what a string ensemble should sound like: like a real ensemble, not like a single violin pushed through a chorus effect. So, in that sense, context is everything.

Sound Synthesis

Anyone who already knows a little about synthesizers could opt for a completely different approach, but the success of this approach will depend heavily on what your synthesizer can do. Put simply: a chorus effect is a really easy solution when you want to simulate the sound of multiple instruments using just one instrument. However, with a synthesizer, you can actually design an ensemble-like sound that doesn’t actually need any chorus at all. Basically, anyone who wants to create an ensemble of eight sound sources using a synthesizer can literally start playing around with eight sound sources. This could be eight oscillators, or maybe eight multi-timbral parts. How this works precisely will depend on the synthesizer you’re working with.

The core goal of sound synthesis is to create as ‘human’ a sound as possible, meaning that the point is to pack the sound with continuous fluctuations in pitch, timbre, volume, timing and length. While acoustic placement is also one of the essential building blocks of any sound, it’s unlikely for a musician to run around while playing, so adding acoustic placement fluctuations into the sound of your synth wouldn’t actually sound realistic.