Logic Pro Stem Splitter

Uppdated Stem-separation in Logic Pro 11.2

For some time Logic Pro has been one of a very few DAW softwares that could offer stem separation from within the program. Even with the previous version, I found this function to be clearly better – as in: more or less free from side effects – than other DAW’s, such as for instance the Presonus Studio One Pro. However, with version 11.2 of Logic Pro, significant improvements have been made to Stem Splitter, as Apple has chosen to call this feature.

At the same time as version 11.2 of Logic Pro for macOS, version 2.2 for iOS (iPad) is also released and both versions contain a lot of new functions and improvements. There, in addition to the updated stem-splitter, we also find new “performance-focused” sound packages plus an improved version of a function that Apple calls Session Recall and which allows you to retrieve takes that you thought you lost because you didn’t record them. It should also be noted that Stem Splitter requires an Apple silicon-equipped computer (M1 or later) or an iPad equipped with an A12 processor to run.

Improved Stem Splitter

Previous versions of this function have been able to split the sound from a selected and pre-mixed audio file into four different components: vocals, drums, bass and other (other). There are, of course, many other companies today that have succeeded in this magic in a more or less convincing way. There are both separate apps and online functions that you either pay per work performed, or on a subscription basis. However, Apple offers the very best variant among those that have this stem-split function built into their DAW, and free of charge, and even when compared to the significantly more expensive variants, Logic Pro’s variant is undoubtedly in the very top tier.

Already in the previous version of Logic the Stem Splitter did an excellent job, but now they have improved the algorithms further and also added some functions. First, you can now also separate guitar and piano tracks with really good results, and secondly, the separations of vocals, bass and drums now even sound notacibly better than before. Stem-splitting from other companies often have a lot of side effects. This can be bits of different instruments leaking into the vocals for example, reverb tails that have been chopped off and so on, but there has also been pure noise that suddenly appeared.

In Logic Pro 11.2, the stem splitting doesn’t always result in perfect raudio, but sometimes we hear absolutely incredible results, especially considering the quality of the audio files I asked it to work with.

Audio files from a PortaStudio

Most of the audio files that I asked the Stem Splitter to have ago with was old recordings that originated from music that I recorded many years ago on my then “top equipment”. This consisted of a Tascam Portastudio 244 – which I won in the magazine HiFi & Musik’s (and probably also the whole of Sweden’s) first serious demo competition in 1986. The jury included the magazine’s editor-in-chief Bernt Hermele, Stig Vig from the group Dag Vag, the sound engineer Bengt Nyquist, and the not-so-unknown Michael B. Tretow (of ABBA fame).

Anyway… on this Portastudio, three tracks were used for analog sounds such as vocals, guitars and harmonica. The fourth track was used as a sync track to control a Yamaha QX5 hardware sequencer, which in turn controlled a couple of drum machines and some synths. There, of course, we found both a Roland TR-707 as wll as its sibling model, the TR-727, which played various percussion instruments. There was also an Akai XR10, which added a little bit more bite to the drums, an Oberheim Matrix 1000, a Matrix 6R and my absolute favorite among rack synths, the Roland MKS-70 Super JX (damn, how I miss this!). 

Eventually, a few more synths were added, but this formed the basis of the arsenal that I used for my first own creations, and which were recorded in a 1×1 meter closet onto this Portastudio of mine.

The Wardrobe Studio was really very tiny…

All of these external sound generators were then mixed live via a simple Boss BX-16 – a really cheap and cheerful 16-channel mixer – along with the three analog tracks down as a stereo file to a Sony PCM-M1 DAT tape recorder. I also had a spring reverb from British Bandive Accessit that I could spice up some tracks a bit with.

Since everything was mixed absolutely live, it was important to act with caution if any audio track needed to be corrected on the fly. It often took two or more attempts before you got a result that you were reasonably happy with.

Before I could afford the DAT tape recorder, I actually used a Hitachi VHS tape recorder. The HiFi soundtracks of these machines were of a quality that was certainly not far behind the first digital recording machines, but VHS tapes are large and unwieldy, plus the machines sometimes had a tendency to jam tapes and then it was all over.

Meticulous restoration

In any case, it has previously been more or less impossible to improve these stereo recordings, unless you just wanted to compress, EQ, add some reverb or some other effect to the whole thing. Until now.

Now you just create a new project in Logic Pro, drag your audio file to a track, click on the audio track and either select Stem Splitter at the top, or go down under “Processing” and select the function there (I’ve never understood the difference).

Either way, you can choose whether you want to split the audio file into all the components that stem-splitter can handle, or if you just want to extract the vocals onto a separate track and let the rest of the sounds be  a combined stereo file. For my own needs, splitting it up into as many “stems” as the function can offer is perfectly fine.

Then, when I have vocals, drums, bass, guitar, piano and other things on separate tracks, I can process them with all the different tools that are available to me, and that may be suitable for this particular song.

Delay and reverb

Delay and reverb have of course been added to separate taps for each track. In terms of reverb, I have used both the Softube Atlantis Dual Chamber – the Atlantis studio in Stockholm in software format – Relab Development’s Quantx Essentials, which is a slimmed-down version of their QuantX Natural Resonance Reverb and which in turn is an excellent software emulation of the Quantec QRS, a piece of hardware created by Wolfgang Schwartz in the 1980s and which is Peter Gabriel’s (and my) absolute favorite reverb at the moment.

On the delay side, I have used both the free app Harrison 3D Delay, Other Desert Citiesfrom Audio Damage and HOFA Plugins Colour Delay, which has a really good ducking function.

Compression and limiting

When it comes to compression, I have mainly chosen to use tools from Relab Development. Their Relab 176 Compressor/Limiter is a painstakingly recreated software version of a true classic on the compressor side, Bill Putnam’s 176 Valve Limiter. We hope to be able to return with a more in-depth test of this superb plugin, but let’s just briefly mention that the developers at Relab emphasize that they have taken the utmost care, first of all of course, at all stages of the development of the plug-in, but then also when they wanted the public’s help with the beta testing of Relab 176.

The developer absolutely did not want any shortcomings in the results of using Relab 176 to be due to the user trying to run the plug-in on a computer that was too slow and underpowered. Therefore, those who signed up as beta testers had to report what type of computer/processor they intended to run Relab 176 on. Only after their configuration had been approved did they get access to a beta version of the plug-in. It should also be mentioned that the version I myself used for this project has been the sharp version, no beta.

Relab 176 is the software version of a transformer-equipped, tube-equipped compressor of the highest dignity from the 60s, and it can sound both incredibly transparent and really naughty and mean, just as you prefer. In my case, I wanted to bring out the raw and a little noisy noisy sound from my old analog portastudio recordings, and there Relab 176 offered a large number of excellent presets to pick and choose from.

Anyway, among the many presets on offer, I found stuff that I found worked great for vocals, guitar, drums … and so on. Behind these presets we find producers like Craig Bauer, Jack Miele, Justin Gariano and Koen Heldens. Perhaps the most fun bit was the fact that a preset that was originally created to function as a Drum Bus compressor also worked great for the entire final mix, or a guitar solo. You choose what you think sounds good, and it is a snap to tweak your own version and then save it as a favorite preset.

I should probably also mention that I also wanted to give the new tracks a little extra saturation, and preferably give them a slightly ”dirtier” sound than the originals. I have therefore chosen settings that sometimes almost felt a little “over-the-top” in terms of distortion and extra compression. But here you’re offered lots of options to influence the end product with your own ideas. On the stereo bus, this time I also used two products from Plugin Alliance/brainworx, their bx_masterdesk True Peak and bx_limiter True Peak. And as I said, I have really gone all-in here too.

Still more plugins to use

On a couple of the old tracks I also took the opportunity to add some extra harmony vocals using the Antares plug-in Harmony Engine. There I simply copied the existing vocals to a new track where I inserted the Antares plug-in. In this track, I reduced the original vocals to a minimum and instead left a bass part, plus a couple of harmonies, at the highest level. Then I was able to automate that track so that the newly created harmony vocals ended up at a level where I thought it was okay. In the mix, I think the “choir” sounds just fine.

There were also a couple of tracks where I discovered that my S-sound was a bit disturbing. There I took the opportunity to try a couple of different de-essers. First Antares Vocal De-esser and then also sonible smart:deess. On this track I actually felt that the sonible plug-in gave a nicer end result.

Leif Mases’ EQ

On the EQ side, I used some of the ones included in the Logic package, but above all, there was another EQ plug-in that I thought worked great. It was the Maselec MEA-2, also from Relab Development. The Maselec MEA-2 is a software version of one of Swedish sound engineer, producer and hardware designer Leif Mase’s most successful pieces of hardware. Leif has worked with great artists like Led Zeppelin, Jeff Beck, ABBA and more, and he has developed the Maselec MEA-2 Mastering Equalizer, which he first built to have solely for his own use.

However, the sound of the MEA-2 became so popular that he had to build more. One of the first copies ended up with Roger Taylor from Queen, and the rest, as they say, is history.

Anyway, Leif Mases is also the man behind an extremely good-sounding compressor Maselec MLA-4. This is also available in a software version from Relab Development, but it was mainly their Relab 176 that I used, and of course the Maselec MEA-2 as the main EQ. This also has a number of extremely useful presets as starting points.

To sum it up…

Stem separation has become something of a buzzword and is an incredibly useful tool for re-mixers and others who need to split a finished mix into some of its original tracks or stems. For my own part, I have chosen the stem splitter function that is now included in the latest version of Logic Pro 11.2. As source material, I have used stereo files of old songs that I mixed directly to DAT many moons ago. I have actually not previously had access to any separate original tracks, so for me the Stem Splitter has been a godsend. 

There are also plenty of other uses for this technology. I have recently read about examples where dialogue intended for film production could be “stem-split” so that voices (what we can call the singing) could be separated from the annoying environmental noise that interfered with much of the audibility of the dialogue. And even when it comes to pure music processing, the stem split function opens up lots of interesting options for affecting the soundscape long after the final mix is complete.

You can find the results of my audio experiments on SoundCloud.

Here’s the original versionen av a song called Rasande tempo:

And here’s the same song after the Stem Split treatment:

You’ll find a few other examples of songs that have been experimented on using the Stem Split function in Logic Pro 11.2 over here:

Now all I can do is to wish you all the best with your own stem split experiments! I hope you have as much fun as I had during the hours I spent dissecting my own old creations. Lest’s keep in contact!

FACTS & FIGURES

Logic Pro

DEVELOPER Apple, www.apple.com

SYSTEM REQUIREMENTS Logic Pro for Mac macOS Sequoia 15.4 or later, iPad requires iPadOS 18.4 or later

PRICE Logic Pro 11.2 for Mac: free update, or £199.99 (2.495 SEK) for new users; Logic Pro 2.2 for iPad: free update, or £4.99/month (69 SEK) or £49/year (690 SEK/år) with a one-month free trial

Relab 176 & Maselec MEA-2

DEVELOPER Relab Development, www.relabdevelopment.com

SYSTEM REQUIREMENTS macOS Sequoia 15.4 or later

PRICE Relab 176: 199 dollar; Maselec MEA-2: 199 dollar

sonible smart:de-ess

DEVELOPER sonible, sonible.com

PRICE 129 €, right now: 59 €

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Gunnar E

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