Logic Pro: How To Use The Stem Splitter

Stem Splitter gives you the option to separate complete mixes into up to four parts: Vocals, Drums, Bass and Other.

We revisit some old tape masters with the help of Logic’s new Stem Splitter.

I covered the new intelligent Session Players back in the September issue, but the other headline feature of Logic Pro 11 is a surprisingly capable stem splitter. The less good news is that the stem splitting facility is only available to those running on an Apple Silicon machine, presumably because it makes use of the AI technology in the M‑series processors.

For those unfamiliar with stem splitting, the aim is to be able to extract individual parts from a complete mix, something that is accomplished on a spectral level and often achieved with the help of machine learning. Unsurprisingly, the results are never quite perfect, as even the best‑trained AI sometimes fails to separate the harmonics of one instrument from those of another, but the way the separation takes place means that if the individual stems are then added back together, the original audio file is recreated exactly — which means you can often usefully rebalance elements, even if the separation isn’t perfect.

Logic Pro’s Stem Splitter is to be found in the Functions menu and it can separate a track into a maximum of four parts, or ‘stems’, categorised as Vocals, Drums, Bass and Other: guitars, keyboards and so on fall into the Other category. If you have guitar and keyboards playing at the same time, you can’t extract the guitar track as you can with some of the more exotic (and more expensive) third‑party stem splitters.

Time To Split

To make this work, all you have to do is import a mix into Logic Pro 11, select it in the Main window and then go to Stem Splitter, which is at the top of the third section down in the Functions menu. If no audio track is selected, Stem Splitter will be greyed out. A window opens showing the four stem options with a tick box by each one, so if, for example, you just want to separate the vocals, you’d only tick the Vocals box. If you want the full four‑way split, tick all four boxes. Having done this, you click Split and in a surprisingly short period of time (typically half a minute for an average‑length song) your stems are displayed as four separate tracks within a Track Stack.

Once you’ve selected an audio track and invoked Stem Splitter, Logic will create a new Track Stack and populate it with the extracted stems.

In my own tests, examination of the individual tracks...