Octatrack Experiments #02 B: Granular processing

I’ve been recording a lot and very busy with life. Since the last post I’ve tried several different approaches to this idea, and while most of them gave some kind of interesting results I wasn’t very happy with them as granulation. I finally managed to get something I like going though.


The idea is to use three flex machines for a stereo effect and each one goes through a filter going from low pass, to band pass, to high pass. Each of them go into individual reverbs. Rate set to timestretch, loop to on TSTR to off, Len to off.

We’ll use slightly different number for each track so we have something similar going in each, but never quite lock in (not that it’s likely to matter since random modulations are computed independently). Whenever there’s a triangle you could use the inverted triangle to give stereo variations if you use the same values.

Rate in the low teens, RTRIG to infinite, retrigger time set to around 2 on all three but different values.

Randomly modulate RATE at 2x ~37 and ~30 amount. You don’t want to use a continuous function for this I believe, since that ends up sounding too much like pitch bending rather than getting some random grains reversed. If using a continuous function you’ll want to have it go really slow and modulate just enough that you get a small amount of reversed time.

Use a triangle at 1x ~20 and amount ~117 to modular the start time. The idea is that this should “scan” the whole sample forwards and then backwards, catching mostly close grains. The superpositions then comes from varying grain size faster than start time.

Finally, use a triangle at 8x ~52 and amount ~33 to modulate retrigger time. Ideally you’d want to use a triangle with some random added, but there end result is not that different and you would have to give up modulating rate or start. If you go too high on the amount, you’ll mostly get glitchy bleeps. This, I think, is a limitation of using a very small amount of grains and imprecise windowing.

One thing to take into account is that you’ll get better results with a rather short sample with this method, otherwise modulating the start parameter like this is unlikely to evenly cover the entire sample. This could be used in conjunction with the crossfader controlling the start time to have this same effect, but for that to make sense one would have to make a pretty long recording, which I’m trying to avoid.


In this example I used a short sample I recorded from a baglama. I set a couple of scenes to play around with the effects mostly.

The “tape” setup is used through the CUE out and some MS20 is fed thought that. There’s some resampling of the tape track and slicing going on, but it’s not too relevant to the result.

Going forward

I have some ideas left, and some of the stuff I’ve been using these last few weeks can still yield some interesting results. One thing I need to explore more closely is manual scanning of the sample using scenes together with the locking other modulation parameters. For example in that last audio, I have a scene set so I can scan the sample but as I go forward the amount that the start time is modulated diminishes. The results from that are not uninteresting, but need some very fine tuning.

The process of setting this up in general is very finicky. Not all sound sources are good for this kind of granularization and changing the sample means you’ll have to change a decent amount of settings too. Speech samples for one are very easy to setup, since you get a better idea of the whole sample by only listening to small fractions. Long drones are the opposite. Ideally I’d like to develop a range of setting that at least sort of work with most reasonable sound sources.




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