These instructions are for Reaper on Windows
- Right-click on track | Spectral Edits | Always show spectrogram
- Peaks Display Settings:
- Drag the top color bar to the left to emphasize the lowest frequencies
- Adjust "freq log," "curve," "contrast," "bright, and bottom color bar by dragging left and right.
On the spectrogram below, the first of each series of green peaks show the leading edge of the kick drum hits.

Zoomed in, the leading edge of this particular kick drum is the purple rectangle on the bottom.

Use scrubbing to find the leading edge of the kick quickly.
- Options | Preferences | Audio | Playback
- Looped-segment mode: -300 ms to 0 ms
- At the edit point, Ctl-Alt-drag the edit cursor handle back and forth over where you hear the kick
You also just do this with the "Spectrogram + Peaks" setting if you don't need the visual boost of the spectral peaks.