Cakewalk Sonar 7: Creating Stretchable Files Doesn’t Have to be Difficult

OBJECTIVE: Convert rhythmic loops into Sony-format “Acidized” files in the easiest possible way.BACKGROUND: “Acidizing” a file so it stretches over a wide range of tempos can be difficult with complex material. But with simple rhythmic loops, if you’re more interested in speeding up than slowing down the tempo, you can “Acidize” the file in a few easy steps. 


  1. Double-click on the file to be stretched to open the Loop Construction window.
  2. Click the Enable Looping button. Sonar estimates the number of beats in the file; if correct, the Orig. BPM field displays the original tempo. If not, enter the correct number of beats in the Beats in Clip field.
  3. For Transient Detect, enter 0 and hit Return. The transient markers that control slicing will jump to the current value in the Slices field.
  4. In the Slices field, choose the rhythmic value that matches the pattern (e.g., with a 16th note-based pattern, choose 16th notes).
  5. If a beat doesn’t have a transient marker, like a 32nd note accent in a 16th note pattern, add a marker in the strip with the other marker triangles by double-clicking above the transient.
  6. If there’s an unneeded transient marker (e.g., in the middle of a sustained eighth note cymbal crash where nothing happens underneath it), remove it by clicking on the Erase tool, then clicking on the marker you want to remove.
  7. If the material is pitched (e.g., synth arpeggiation), click the Follow Project Pitch button and select the file’s original key from the drop-down menu. With unpitched material, leave this field grayed-out.
  8. Click on the floppy disk button to save the file; it will contain the additional stretching metadata.


  • With many patterns, steps 5 and 6 may not be necessary as 16th note slicing will work just fine.
  • If the drum pattern was played by a human, transients likely won’t fall right on the beat. Move them to line up with the transient start by clicking on the red triangle and dragging. 
  • When creating a file from scratch that you want to stretch, choose a slow tempo, like 60bpm. Tempo-stretching works better for speeding up than slowing down.
  • In step 8, you can also save the file by dragging the clip to the desktop.