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What is granular synthesis?
What sounds can we make with granular synthesis?
We explore the fundamentals with FL’s Granulizer.
If you produce music with a DAW, you may have noticed a built-in granular synthesizer. If you’re into modular synthesis, you may have seen a Clouds module being used to make ambient soundscapes. Perhaps you’ve even tinkered with a granular synthesizer to produce some interesting – if chaotic and random – sounds.
But there’s a lot going on under the hood that you may not have considered. In this article, we’ll give you a crash course on granular synthesis and explore the fundamentals with FL Studio‘s Granulizer instrument.
Granular Synthesis Explained
Granular Synthesis is the process of chopping up a sample into tiny pieces, called “grains,” and then playing these grains at different speeds and intervals in response to incoming MIDI notes. This process breaks the link between the pitch, speed, and duration of a sound. The resultant effect has been used for applications including pitch shifting, glitch effects, and drone ambiances.
So the term synthesis here is somewhat misleading as granular synthesizers really rely on samples. But you will find many “synth-like” controls on these instruments, and they respond to MIDI just like any other synth, so it’s not an inaccurate term either.
No two granular synthesizers will be alike, as there are numerous ways you can use grains to play back a sample. Some may offer more in terms of filters and effects, as well.
Exploring The Granulizer
With granular synthesis, the distance between grains and their spacing in playback are important controls that determine timbre, and they are unique to granular synthesis.
Let’s look at a basic granular synthesizer to get a better grip on what this means and how it sounds. In this article, we’ll use the Granulizer that comes with FL Studio, though most granular synths should have the same controls to play with.
Wave Spacing Control
When samples are chopped up, they are arranged into a grain table, similar to a wavetable.
The Wave Spacing control changes the spacing between grains. At a setting of 100% (the default) the sample plays back normally.
Dialing it up means there will be more space between the grains in the sample.
Dialing it down means there will be less space between the grains in the sample.
Notice that since there is less space between generated grains, there are more grains generated from the same sample, and the entire sample lasts longer as a result.
Negative values will make the synthesizer interpret the grains backward. This means the grains will be played from last to first; it does not mean the grains themselves will be reversed.
This dial controls how much space goes between the grains in playback.
It’s important to differentiate this from Wave Spacing. Wave Spacing affects how the sample is chopped up into grains, while Grain Spacing affects how the grains will be played back after they have been chopped up.
Dialing it up means there will be more space between the grains in playback.
Turning it down means there will be less space between grains in playback.
Similarly, when there is less space between grains, the overall sound becomes shorter
The Time Dial
This changes the starting point of your grain table. This can drastically change the sound of your granulizer depending on the timbres in the sample itself. For our example sound, you won’t hear much difference, but try loading in a 30-second montage of various clips and you’ll hear a big difference.
Importantly, each grain can be changed in several ways. First, the envelope of the grain is adjustable with the attack and hold knobs.
For those who are familiar with ADSR envelopes, this is basically a reduced version of that.
Attack controls how quickly the grains fade in and out; it is both the attack and release.
The Attack is responsible for the length of the fade-ins and fade-outs and therefore the smoothness of the transitions between one grain and the next.
Notice how the increased attack actually increases the length of each grain so that there are also fewer grains in the sample.
Hold controls the length of the grains’ peak amplitude. In this next example, you can contrast the length of the hold times more distinctly because the attack has been turned down.
Together, the attack and the hold control the length that each grain gets.
The length of Hold plus two times the Attack (the fade in and fade out) accounts for the whole grain.
Grain Length = Hold + 2x (Attack)
Now let’s take these fundamentals and apply them.
Applications of Granular Synthesis
Granular synthesis can be used to alter the pitch of a sample without altering its length, and it can be used to alter length without changing pitch.
Normally, when you speed up a sample, two things happen:
The sample goes up in pitch because the wave is being squished together
The sample becomes shorter in length because the sample is going at a faster speed.
However, with granular synthesis, you can essentially disconnect the two effects and allow for one or the other.
Let’s first try to pitch shift a sample up without changing its length. To do so, we want to change the pitch of each of the grains.
Some granular synthesizers will have a knob dedicated just to the grain pitches. In FL Studio’s Granulizer, grain pitch is controlled by the MIDI input (the notes from your keyboard or the piano roll). So in this case we can just play a different key to change the pitch.
Let’s try going up an octave by pressing the key one octave up.
Now you’ll notice that the pitch is up, but since each grain has been reduced to half its length, the sample is reduced to half its length
You want to lengthen the sound by turning down the grain spacing and wave spacing so that there are more grains and waves in the sound.
I found that the sweet spot for me was 88% for grain spacing and 92% for wave spacing but these numbers will change depending on the sample and how much you have pitched it up. In addition, I increased the attack length to smooth out the transition between grains.
Slowing a Sample
Now let’s lengthen a sample without changing its pitch. Usually, slowing down a sample would make the pitch go down.
To prevent the pitch from going down, keep the MIDI input on the same key to keep the same pitch. Then, to lengthen the clip, increase the grain spacing to create a longer sound, and then adjust the grain spacing, the attack, and hold dials to taste.
Now you can see that the silences are filled out. The pitch is the same, but it has become a longer sample.
In fact, this is exactly what many time/pitch stretching algorithms are doing behind the scenes. Some of the artifacts from these processes might seem familiar to you too.
They often occur when you stretch something too long or pitch it down too low using one of these algorithms.
The Glitchy Voice
With some simple automation, granular synthesis can help you create that effect that you hear in EDM music-and also when your colleague’s got a bad Zoom connection.
First, we find a grain table that we’re happy with, and then we automate the spacing between the grains to create a glitching out effect.
Drones and Pads
We can also create morphing pads and drones that would work well as ambiances.
To make things a bit more dynamic, now would be a great time to explore the effects panel of the granulizer.
The panning knob will pan odd and even grains to the left and right, higher values increasing the panning.
Depth and speed change the parameters of an LFO that is mapped to the wave spacing–this means that the LFO is basically modulating the grain table.
Rand will change the order of the grains randomly.
Here are some drones that come from the same vocal sample used previously, utilizing these controls.
The resulting sound is always shifting and quite unexpected, and it shows the power of granular synthesis.
While some of these controls may vary between different granular synths, the fundamentals will always be the same. And with a little tweaking, you’ll be able to expand your sonic palette, whether for EDM or ambient music.
Q: What does granular synthesis sound like?
A: It can sound like anything! It depends on the underlying sample being granulized. There are plenty of examples in this article showing how a single vocal sample can be turned into many different things.
However, just to generalize, the shifting, warping effect found in granular synthesis has often been used for drones and ambient pads.