Fig. 1: This MIDI clip triggers captured slices at 1-bar intervals, but each note extends an extra two beats to -accommodate a ping-pong-delay tail.
Add a random element to note or automation sequencing, and you get varied results. If you simply loop the process, you'll get good takes interspersed with bad. Furthermore, the track will sound random — every take will be different (see Web Clip 1). One solution is to capture many takes, combine them in a multisampled instrument, and then create a composite track using the best ones. Here, I'll describe how to do that in your DAW, and then I'll discuss the potential pitfalls. If your computer is a Mac, you can automate the process and avoid some of the tedium by using Redmatica AutoSampler (redmatica.com).
In my examples, I've used a drum-sequencing script for Native Instruments Kontakt called Mobile Drums, from Soniccouture Scriptorium (soniccouture.com). It is a 6-track, 16-step sequencer, with randomizers that shift the step positions, change the triggered drum sound and its level, and play drills (rapidly repeated notes). For each of the six tracks, you set how likely to occur each of these transformations is, and how radical each one should be. Any incoming note starts the sequence playing at the host DAW's tempo, and the sequence continues until the note is released. The incoming note's pitch doesn't affect the sequence. You can use the Mobile Drums script with any Kontakt 2 or 3 instrument, but it's intended primarily for percussion.
In Your DAW
Once you've set the tempo of your project and decided on the length of individual takes, create a looping MIDI clip to trigger the synth or sampler you're using for the source material (Kontakt, in my case). If the sound has a tail (as created by reverb, echo, or delay effects), the MIDI clip's loop should be long enough to capture the tail, but the trigger note it contains should be the length of a take. For instance, if you want to capture 1-bar drum patterns, the trigger note should be one bar long — but you might loop it every two bars. If you do not extend the loop in this way, the tails will be cut off when the MIDI clip loops (see Web Clip 2).
Repeat the trigger loop for the number of takes you want to capture, then render the track as audio. Slice the rendered audio clip into pieces that match the loop size (two bars in the above example), and use them to create a multisample map in your sampler. The length of the note you use to play a slice in your sampler determines how much of the slice plays, so the trigger notes should be long enough to include the tails. On the other hand, they should be spaced at intervals the size of the take length. That will cause consecutive trigger notes to overlap, which will not be a problem unless they trigger the same multisample zone. If you want to play the same zone twice in a row, copy it to a new multisample zone and trigger the two zones alternately (see Fig. 1 and Web Clip 3).
As an alternative to sequencing the slices, consider using a step sequencer or triggering the slices manually in real time. In the latter case, you might want to quantize the trigger notes. And if your DAW doesn't support real-time quantizing, you may be able to rig up a transposing step sequencer or an arpeggiator to do the trick.
AutoSampler automates the process, including creating a multisampled EXS24 instrument. If your sampler doesn't import EXS24 instruments (most do), it's a simple matter to create your own multisample map from the WAV files that AutoSampler creates. The program does much more than this, including creating layered instruments with controller crossfades, and capturing multiple presets using MIDI Program Changes.
You start by setting Scan parameters to encompass a range of notes (pitch doesn't matter in this example) corresponding to the number of takes you want to capture. Then you set the take size in milliseconds (2,000 ms for 4 beats at 120 bpm). AutoSampler automatically takes care of capturing the tail by continuing to record until the audio drops below a threshold that you set on the Samples tab. Click on the Start button, and grab a cup of coffee.
Len Sasso is an associate editor of EM. For an earful, visit his Web site atswiftkick.com.
Scriptorium from Soniccouture includes many random processes and instruments to illustrate them in its 35 scripts for Native Instruments Kontakt 3
Redmatica AutoSampler automates the process of creating multisamples from synths, samplers, and random sequential processes
August 2008 EM review of Redmatica Compendium