Granular Synthesis is the concept of processing synthesis using granulation. Granulation, or 'Grains', are the divided slices of a sample or waveform, which are then reorganised to form another waveform. Basically it represents sound as a stream of grains. Grains can vary in duration, amplitude, and internal details such as pitch and pan. Granular synthesis is the core technology behind the latest time-stretching and pitch-shifting algorithms, but it can also be used to generate extraordinary evolving soundscapes.
Alchemy, Logic Pro X's newest flagship software synth instrument, offers just that. Apart from it's well known synth and sound design elements, Alchemy provides the tools needed for granular synthesis.
Alchemy generates grains by extracting 2 - 230 ms granular slices from an existing sample. The amplitude of each grain is then shaped by the 'window', where you can modify the pitch and panning, before it reaches the output. Grains can then be time stretched, pitch shifted, and scrambled into random orders to create a completely unique sound from the original sample.
Parameters of Alchemy consist of Position Control, which determines the starting point of the wave or source. 0.0 = the beginning.
Modulation can be added via an LFO.
Stretch which determines the rate that the playback travels through the sample without affecting the Pitch. When this is set to 0, the playback will be frozen to the position, allowing you to focus on a series of grains.
Effects can then be applied for futher sound design processing, such as distortion, reverbs, and delays, as well as allowing modulation of the filters assigned to these effects for sound design enhancement.
Course tunes the sample without affecting the samples tempo.
Volume, self explanatory.
Size will change the duration of the grain between 2 and 230 ms.
Density which determine how many grains will be overlapped at any one time, from 1 - 10.
And the Window Control, which determines the envelope shape that is applied to each grain in terms of amplitude, ASDR.
I took on the Granular approach, and loaded in a Sitar Gestures F# sample into Alchemy, making sure that the Granular function was selected, located at the bottom left of the interface. I then imported the sample and started to play.
By selecting the |A tab on the far left, I was then able to see the physical wave form embedded in the instrument. Now that my source was in place, I started toying with some of the parameters. Using the Size, and Density pots to shape the granulated waveform. Then I experimented with the start position using the Position pot, which moves the start point to wherever sonically desired, and adjusted the speed. In this case, I slowed it right down, so it sounds pad like.
Once happy with the shape, I activated the Filter function, and assigned some LFOs to each parameter. Keeping it simple, I applied LFO1 to the Cutoff, Resonance, and Drive Filters, similar to any synthesiser. Then experimented with the setting, aiming to achieve quite a dark an atmospheric pad. Playing it back, the sound has a very long decay time, and has a lot of movement. It has a very dirty, LoFi, Glitch like quality. Then I applied some effects, located in the bottom output window.
I used an Acoustic Reverb, a Delay, a Distortion, a Pan, and a Bass Enhancer, all of which can be tweaked in their own ways. Further development of this sound can comprise of applying extra LFOs, or Envelopes, as well as, layering up more samples, to really create something new and exciting. Step sequencers as well as AHDSR Envelopes can be toyed with to shape that way the sound travels, giving you control over the effect, which would be a largely used tool for film scoring. Here what it sounds like:
Sound designers will have a field day with Alchemy, and should try it if they haven't already.
Gale, D. (2018). Logic Tutorial: Granular Synthesis With Alchemy. Retrieved from http://www.musictech.net/2016/03/logic-granular-1/
Price, S. Granular Synthesis |. (2018). Retrieved from https://www.soundonsound.com/techniques/granular-synthesis