Pull a useful part out of a rehearsal recording with Koala Sampler

Imagine a rehearsal recording with one bass phrase you want to learn. Everyone is playing together, and the phrase is hard to follow. A useful first goal is modest: get that passage onto its own pad, hear it clearly enough to study, and save the segment you want.

This walkthrough follows Koala’s current manual, checked on 18 October 2026; it is a documentation-based route, not a hands-on quality test. The instructions use an iPhone as the reference device. You will need Koala installed, headphones and an audio file from your own rehearsal.

Open Koala as a standalone app. Its manual says stem splitting is unavailable in AUv3 mode, where it runs inside another music app. The documented import rule is broad: audio your device’s default player can play should be importable.[3][4]

1. Start with one short passage

Choose a short excerpt containing the musical idea you want. Twenty seconds is a sensible example, not a processing limit. A whole rehearsal creates more material to sort through before you have decided whether the isolated part helps.

In Koala, choose MENU → NEW. Save any current work if prompted. Select an empty pad, open MENU → IMPORT AUDIO, choose your recording and tap LOAD. Save the project under a useful name, such as “Tuesday rehearsal — bass phrase”.[2]

Drag that pad onto another empty pad to copy it. On the copy, tap EDIT and move the red selection’s corners around your excerpt. Choose TOOLS → CROP to discard the rest from this working copy.[1]

2. Separate the part

On the working pad, open TOOLS → SPLIT STEMS and switch on BASS. Other choices are DRUMS, VOCALS and OTHER. Each selected part gets a free pad. Leave MERGE SELECTED off.[1]

Choose FAST or HI QUALITY; the developer describes the second as slower and cleaner. First use downloads a few hundred megabytes. Allow processing time, which varies; Koala warns about insufficient free memory.[1]

3. Listen for the job you need it to do

Play the extracted part, then return to the original recording. Ask a musical question: can you follow the note changes and the timing more easily? Listen especially where a cymbal hit, vocal syllable or guitar chord coincides with the phrase you want.

For learning a bass line, clear note changes may be enough. For reusing the audio in a new track, listen more closely to the attacks and the spaces between notes. If a sound seems strange, check that moment against the original before deciding it belongs to the performance.

This is a listening decision you make for your recording. The labels FAST and HI QUALITY cannot tell you whether a particular phrase is useful.

4. Trim, then export the edited sample

Select the extracted pad and use EDIT’s red selection handles to frame the final phrase. Pinch to zoom. Replay it until the beginning and end sound right.[1]

Choose MENU → EXPORT → SELECTED SAMPLE, then EDITED. That choice applies the playback selection and other pad edits. RAW exports the underlying sample without those changes, so it can bring back audio outside the phrase you just selected.[2]

Choose WAV for a straightforward audio file and keep the session sample rate, marked by a speaker icon. Exporting at a different rate resamples the audio. Give the file a descriptive name when saving or sharing it, then play the exported copy to check its boundaries.[2]

If a step gets stuck

For a memory warning, try a shorter excerpt. For missing controls, use the phone editor’s page arrows. For a missing splitting feature inside a host app, reopen standalone Koala.[1][3]

Downloaded separation networks can be removed through SETTINGS → EXTRAS → Stem splitter files. Manual trimming in this workflow also avoids needing Samurai’s separate auto-chop or time-stretch features.[5][6]

You should finish with a saved Koala project and one exported passage. Now put the instrument in your hands, play along, and decide what the separation made easier to hear.

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