A few people asked how I use chord samples in the Octatrack, so I put together some more info here. You can download a bunch of my chord samples in the link below, and any .OT settings files, so a lot of them should be sliced and ready to go. I included the MIDI files if you want to make your own samples in the same format.
A lot of the sounds in Debiasing and Utility come from using polysynths in place of oscillators in the modular system, layering multiple chords and running them from a stereo bus through dynamic processors in the Eurorack (envelopes / LPG’s / filters / VCAs etc). I wanted to make that process portable to do it live, and found a solution with the Octatrack, using chord ‘sample chains’ (single files containing a number of equal sized samples) that it automatically splits into up to 64 slices. I made a MIDI file with 64 chords, arranged into 8 modes with 8 inversions each, with the first half being major, and the rest minor. I then played this MIDI file through various synths and recorded the audio, doing it for three pitches over one octave. Since I’d be adding filters and dynamics after, I just needed the raw waveforms, so filters were set fully open, VCA envelope sustain to maximum, and attack and release set to 0 so the slices don’t bleed into each other. The audio files have to be trimmed to the same length as the MIDI file for it to work.
I mostly used it for live shows, running chords from the Octatrack into the modular, but it’s also fun with just the Octatrack’s internal envelopes / filters / dynamics.
Download: Chord Samples / MIDI files
Load sample
Load up a sample into a channel slot. Use the file closest to the key you’re working in, with my sample chains thats either C, E, or G#. So if I’m in the key of F, I’d choose E and pitch the sample up 1 semitone.
Once you’ve loaded a sample, go into the edit page (Function + Bank)…
Create slices
In the SLICE screen on the bottom, hit YES and go down to CREATE SLICE GRID.
Choose number of slices
This should be whatever number of samples you have in your sample chain, which is 64 in my case. Choose ‘yes’ to zero crossings in the next dialogue.
Trim slices
I found that its good to go through the samples and make sure the start points are in the right place, as recording hardware over MIDI can sometimes give timing inaccuracies, meaning a slice starts with a tiny bit of the previous slices waveform. A few shortcuts make this easy to go through: Function+Yes will play whatever slice you’re on, zoom in with F knob, left/right moves between slices, Function+A knob moves the start of a slices loop point while snapping to zero crossings (to avoid clicks), and Function+C knob does the same for end points. once you’re done, go to FILE and select SAVE SAMPLE SETTINGS, then ‘Yes’ to OVERWRITE in the next dialogue.
Configure channel settings
Double tap the Playback button and change the settings here. Loop mode in PIPO means ‘pinpong’ which loops the sample by reversing direction at the start/end points. SLIC must be set to ON, and time stretch should be left off.
Configure playback settings
Going out of the setup screen, you see the start point now has a scale with SL1-SL64. Choose a slice in the mode you want as a starting point, and in the sequencer you can make trig locks to choose a different slice/chord for each step. Set the Hold/Release parameters on the Amp page to something useful.
LFO’s
Sample & Hold LFO’s are great to give variations on each trigger. The settings here give a different filter frequency for each trig. You could also play a different mode/inversion at random putting an LFO on the slice position (although there’s a bug in the Octatrack that clicks sometimes when choosing sample slices with scenes or LFOs).
Filter
With the LFO set as above, and filter WDTH on a low setting, you get a bandpass filter that takes a random base frequency for each trigger, within a range set by the LFO DEP and the BASE value.