Xx Tutorial 2: Using Random & Evolve By Len Sasso and Eric Wenger

One of the nice things about XX's Random Generators is that they can be constrained to a track's existing melodies and harmonies. They provide nice ways to explore possible arrangements and harmonizations of an existing theme. In this tutorial, we will build polyphonic structures using iterative calls to the Smart Random function.

For a more in-depth discussion of "random" parameters, refer to Tutorial 5.

We start the piece with a similar set-up as to the one created in Tutorial 1 using only four tracks.

Step 1. Set-up

The basic theme will be the "slow strings motif" composed in Tutorial 1, enhanced and converted in C Major.
(For convenience, we have provided a file with the main theme "Random&Evolve1")

• A: Duplicate the basic theme 5 times using the methods shown in Tutorial 1.

Step 2. Create a Bass Track.

• A: Select the bass (blue) track as was shown in Tutorial 1. Select measures 1-21.
• B: Chose Pattern Menu->Smart Random. We don't want the bass to be too fast or busy so we set the duration to 240 ticks (quarter notes) and the rhythm to that shown below. Note: since we want the bass to repeat exactly every 16 quarters, we set the feedback to 100.
  
  
• C: Click Preview several times until you find something to your satisfaction. Every click will propose a different solution. When you are happy with the proposed track, click the Accept icon to insert the bass track.
  Chances are that the bass will be too high. Since the newly created notes are always selected when they are created, use page down to transpose the bass as many octaves as needed.
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• D: Repeat same steps for measure 21-29 and 29-37

Step 3: Create the Harp track (red).

• A: Select the Harp track. Select measures 5-21 using the Bar Select Area to specify where notes will be created.
  
  
• B: Choose Smart Random again.
  Set the duration to 120 ticks (eighth notes) and the rhythm to X - X - X - XXX - XXX - XX ( '-' being silence)
  Since we want the Harp to evolve over time, but not too randomly, we set the feedback to 90.
  

• C: Click Preview several times until you find something you like. Every click will propose a new series of notes.
  When done, click the Accept icon to insert the Harp.
  
  
• D: Repeat same steps for measures 21-29 and 29-37 to follow bass changes.
  You should have something similar to "Random&Evolve 2"

Step 3 Add the piano.

• A: Copy measures 13-21 to 37 -45. Select measures 37-45
  B: Choose Smart Random again. Set it up as shown below:
  

  Here we set up a more elaborate rhythmic pattern and set the duration parameter back to quarter notes.
  

• C: Click the Accept icon to insert the new notes.
  

Step 4 Evolving Your Composition

Evolve provides interesting ways to explore variations of existing music. In this example, we will evolve measures 29 to 37 to find an alternate modulation.

• A: Select measures 37 through 45
  
• B: Choose Evolve... from the Patterns menu. When the evolution window opens, set the values as shown here. Note the piano has a higher probability of being mutated than the other tracks.
  
  

  
  Here are some things to note about the evolution function:
  
  

  • The numbers under the 16 track colors determine in what percentage of passes that track will be changed.
  • If the "Mutate Just One Note" box is checked, at most one note will be changed if the track is changed at all in that pass (see above).
  • The changes at each new pass apply to the results of the previous pass hence the name "evolution."
    
• C. Evolve your composition by clicking the green Accept icon at the bottom of the window. Observe how the melody slowly diverges from the original. You may listen to the result and choose a particular measure to keep. If unhappy with the result, you can undo and try again. A different version will be proposed each time you apply this process. You may also tweak the mutation probabilities to ensure more stability. For example, the bass line can be kept intact by setting the first probability to zero.
  
  "Random&Evolve 3"

More to try :

Combining feedback loops multiples of 4 and 6 yields often interesting rhythmic results. "Random&Evolve 4" was composed exlusively using Smart Random with a loop a of 3 and b of 8 for the bass and harp and a loop a of 8 and b of 12 for the piano and string.