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Creating Loop Points

Looping is a technique that stems from the days when samplers had tiny memory stores (by today’s standards) in which to load samples. Many sounds start off with complex attacks but soon settle into a more or less steady waveform. By repeating this “settled” area, a sample can be sustained indefinitely without using up limited memory space. Even with modern software samplers that have access to gigabytes of memory (like the EXS24), looping is a useful technique to create sustaining sounds out of samples that are otherwise quite short, such as the audio file you are working with in this exercise.

By default, this editor displays only some of the Zone parameters, while hiding others, including the Loop parameters. You can select the parameters you want to display in the View menu.

  1. From the local View menu, choose View All.

    04fig13.jpg

    All Zone parameters are displayed, including the Loop parameters.

    To enable looping, you first need to select the Loop On option.

  2. In the Loop parameters, select Loop On.

    Although you could enter start and end times (by sample number) in the parameters area, doing so would be arbitrary and counterintuitive. Selecting an area on the waveform itself using the Audio File Editor is much easier.

  3. In the Audio File parameters for the zone, click the disclosure triangle to the right of the audio file name and choose “Open in Sample Editor.”

    The Audio File Editor opens, displaying the referenced audio file, Vox Note.aif.

    You can set the Audio File Editor’s timeline to display time using various units of measurement, depending on which is most useful for the task. For example, when setting loop points, you may find it most helpful to view the timeline in samples (1 sample = 1 ÷ sample rate per second.) That type of timeline setup corresponds to the numerical display in the EXS24 Instrument Editor.

  4. From the local View menu, choose Samples, if necessary.

    04fig17.jpg

    The timeline is now displayed in samples.

    The trick to setting loop points is to find a sustaining portion in the audio file you can repeat without interruption. To make smooth edits, you must make selections that do not interrupt the waveform above or below the zero axis (thereby creating an audible click). When you enable “Snap Edits to Zero Crossings” in the Audio File Editor, all new selections will be justified to the nearest point the waveform crosses the zero axis.

  5. If not set already, choose Snap Edits to Zero Crossings from the local Edit menu.
  6. Using the help tags, select an area from approximately 28800 to 91900 samples (refer to the following figure).

    You can audition your selection by selecting the Prelisten and Cycle buttons at the top of the Audio File Editor.

    04fig19.jpg
  7. Click the Prelisten and Cycle buttons to listen to your selection looping.
  8. Click the Prelisten button to stop playback.

    Now that you’ve identified the area you want to be looped, you need to set the start and end loop points to the zone in the EXS24 Instrument Editor.

  9. From the Audio File Editor’s local Edit menu, choose Selection > Sample Loop.

    The Sample Loop lane in the Audio File Editor displays the selected area in orange.

  10. Close the Audio File Editor.

    The results of your selection appear in the Loop parameters of the EXS24 Instrument Editor.

    04fig21.jpg
  11. Hold down C3 on your MIDI keyboard, listening to the result.

    The sample plays, now looping the selected area for as long as you hold down the key.

    To aid you in smoothing out the repeating loop’s start and end points, you can apply a short crossfade (much as you would smooth region transitions in the Tracks area).

  12. In the Loop parameters, double-click the Xfade field and enter 30. Press Return.

    An option is also available to make the crossfade equal powered, which creates an exponential curve with a 3 db volume boost in the middle to compensate for the volume dip that normally occurs in a linear crossfade.

  13. In the Loop parameters, select the E. Pwr option.

  14. Hold down a C3 on your MIDI keyboard, listening to the result.

    The sample plays, smoothly looping the selected area for as long as you hold down the key.

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