Tech Tip:Signal Processing With Propellerheads' ReCycle

ReCycle can do a lot more than create REX files … like signal processing.

By Craig Anderton



Propellerheads'  ReCycle is a cross-platform software tool for creating REX files, which  can stretch tempo and pitch independently. The process works by cutting  a digital audio file into multiple slices, usually with the cut points  at steep attack transients. These slices are triggered by MIDI; as the  tempo of the host DAW or sequencer slows down, the slices are triggered  further apart, thus slowing down the phrase. Faster tempos trigger the  slices closer together. (Pitch transposition is a separate process that,  while not as effective as time-stretching, is satisfactory for  relatively small transposition ranges.)


The  REX time-stretching process is optimized for sounds like drums,  percussion, and other instruments with sharp, defined transients. But  for groove-oriented music, ReCycle can also be a wonderful processor for  imparting "synchro-sonic" (beat-related) characteristics to sustained  sounds. I used this technique a lot with guitar power chord samples on  the Technoid Guitars sample CD so they could pulse with the  beat instead of just sustain—think of it as 21st century, synchronized  tremolo. However, this technique also works with vocals, bass, string  parts, and just about anything that sustains.


We'll start with creative signal chopping, then move on to some other ReCycle processing tricks.


Rhythmic Chopping


Suppose  there's some audio in your DAW program, like a sustained chord, phrase  with multiple chords, vocals, or the like, and you want to create a 16th  note tremolo effect that chops the sound. Define the region of audio  you want to process (make sure the boundaries fall precisely on beats,  and note the total duration in measures + beats). Then, export the  region as AIFF or WAV audio, 16 or 24 bits. Open the file in ReCycle,  then:


ReCycle Processing, pt.1

1. Go View > Show Grid. Enter the duration in bars.


ReCycle Processing, pt.2


2. A grid appears, with sub-divisions for 16th notes.


ReCycle Processing, pt.3


3. Go Process > Add Slices to Grid. This adds slices at every 16th note.



ReCycle Processing, pt.4


4. Click on the "Preview Toggle" icon.



ReCycle Processing, pt.5


5.  Click "Play." You'll hear the original sound with small gaps, and  possibly clicks, at the slices. If you like this sound, fine. But let's  click on the Envelope icon, then refine the sound further with the  envelope options.



ReCycle Processing, pt.6


6.  Use the envelope Decay control to edit the slice decay time (try around  300 ms to start). When you click on "Play," you'll hear a decaying  sound every 16th note.



ReCycle Processing, pt.7


7.  Experiment with the Attack control. A 1.0 ms setting minimizes clicking  at the slice points; longer settings give an "attack delay" effect,  where each slice fades up to maximum.



ReCycle Processing, pt.8


8.  If you plan to stretch the audio to a different tempo, slow it to the  minimum tempo you expect to use, and adjust the Stretch control to  obtain the best possible sound quality. Also check it at the highest  anticipated tempo, and choose a Stretch setting that gives a good  overall compromise sound.


Done!  If you save this file, it will be in REX format, suitable for use in  supporting programs like Reason, Cubase, Logic, Sonar, etc. However, you  don't have to save it as a REX file (good news if your DAW of choice  doesn't support this format); you can export as a WAV, AIFF, or SD II  file, then simply bring it back into the program from which it came. To  do this:


  1. Go to Process > Transmit As One Sample before saving. Otherwise, each slice will be saved as an individual file.

  3. Go to File > Export, and choose the file type.

  5. Click on Save.


Advanced Chopping


Slices  need not be on rigid boundaries, nor constrained to the grid. So, you  can easily create syncopated patterns, or place the emphasis on certain  beats—like having the longest slice on the downbeat. Just place the  marker where you want a slice to start, or use the hide function (click  on the Hide icon, which looks like an X) to turn off a marker if you  want a longer slice.


There's  even a way to create gaps and stuttering effects, because ReCycle lets  you mute any number of slices. Select the Pencil tool, then click on the  marker that begins a slice to be muted (or Shift-click for multiple  markers). Click on the Silence Selected icon or go Process > Silence Selected.  This mutes the slice following each selected marker. If you export the  file, there will be silence wherever the slice was muted.


Before and After Processing


This  shows a file before and after processing. The top file is the original  audio; note where the markers were placed in ReCycle. The lighter  section represents a slice that was muted. The lower file shows the  results of exporting as an AIFF file, with a fairly short Decay setting.  The red lines were added to emphasize how the audio waveform lines up  with the ReCycle markers. Note how the original sustained chord is now a  series of rhythmic pulses.


Another Gapping Option


You  can also create gap/stutter effects very easily, albeit not with the  same kind of rhythmic precision as the previously-described methods,  just by editing the Gate Sensitivity parameter. This applies a gating  effect to individual slices that turns on at the start of the slice, and  mutes the signal when the level falls below the Sensitivity threshold.


Actually,  the process is a little more complex than this, because even slices  with all levels below the threshold may have a little signal present at  the start of the slice. But don't worry about the fine points; just play  the file, adjust the Sensitivity, and if it makes groovacious sounds,  you're set.


Slice Jumbling


Although you'll usually want to save a file as a single entity, if you uncheck Process > Transmit as One Sample,  each slice will be saved as an individual file. These can then be  re-assembled in your DAW. For the most foolproof results when  re-assembling, before saving slice at equal intervals like 8th or 16th  notes (although the adventurous are welcome to experiment).


These  slices are numbered, so it's easy to bring them back into your DAW in  the original order (for best results, choose an appropriate snap value;  some snap functions allow snapping to event boundaries, which makes it  simple to "butt splice" the various slices together). But why be normal?  Change the order of the slices within your DAW, remove slices,  duplicate slices, snap them to different beats, etc.


The Other Kind Of Normalization


ReCycle can normalize a file (usually done before slicing, but it can be done afterward as well). However, go to Process > Normalize and you'll see two options: normalize Each Slice or the Whole File. If  you normalize all individual slices, this can bring up soft parts and  alter dynamics in interesting ways.


A Home For Transients


Finally,  don't overlook the Transient Shaper as another useful processor.  Superficially it resembles a compressor, but it works on a different  principle. Rather than burn up a lot of words here describing it, I  suggest learning about it by checking out the supplied presets, and  tweaking them to see how the controls affect the sound.


Note  that using these processors may change the gain, possibly causing  clipping. Periodically check the meters in the lower right corner of the  main sample window, and adjust the Gain control for the highest signal  level short of distortion.


Yes,  ReCycle can do a lot more than create REX files—especially for  beat-oriented music. Mess around with it, and the results may surprise  you.