Brashaw Report

Stem separation is a technology that has been around for a number of years. From desktop applications like Izotope RX10 to web-based stem separators like LALAL.AI, there are plenty of tools out there that can analyse audio files and then split them into stems of individual instruments.

However, up until very recently, none of these stem separation tools were able to work in real-time. Instead, stem separators would have to analyse audio files offline – a process that would often take a long time – and then export separated stems to be listened to individually.

The major issue with this type of stem separation is that the results of alterations to parameters are not audible immediately, so making adjustments is a trial-and-error process. This can be a time-consuming process and a frustrating one.

All this, it seems, has changed recently with the introduction of a number of real-time stem separation tools. And the latest to enter the fray is Acon Digital’s Remix.

Remix is the first real-time stem separator that is available as a plugin that can run in your DAW.

With Remix’s intuitive and first-of-its-kind workflow, producers can now adjust separation parameters on the fly and hear how these changes affect the quality of separation immediately. Let’s take a deeper look and see how Acon Diigital’s Remix performs in the real world.

Cutting-edge stem separation

Remix from Acon Digital can separate a fully mixed-down audio file in your DAW of choice in real-time – on that front it more than delivers.

Load the plugin on an audio track containing an audio file of a full mixdown, press play, and Remix will immediately start separating your audio.

Audio can be separated into five predetermined types of stem: Vocals, Piano, Bass, Drums, and Other. As your DAW plays back you can solo, mute, and adjust the gain of each stem, as well as adjust the sensitivity of the separation on each stem, all in real-time.

It’s a very intuitive workflow for the average music producer as the interface reflects that of a traditional mixer which you would find in every DAW or studio.

Remix, separates audio into stems so quickly and simply that it’s easy to not quite appreciate how incredible the feat of real-time stem separation is. To recognize how impressive it is, it’s something that has to be experienced first-hand.

Separation quality

We tested Acon Digital Remix on a range of different tracks and were generally very impressed with the results.

Inevitably some digital artifacts occur when listening to a soloed stem, but this is to be expected with digital stem separation.

The amount of digital artifacts is comparable to any other stem separation tool on the market. This is very impressive when you consider that Remix is doing this separation in real time – something that no other stem separator can do.

Though Remix does an incredible job of performing real-time stem separation, it does introduce some latency and artifacts when separating audio in real-time.

This is annoying but not really a huge problem. The real-time stem separation is useful for dialling in parameters and quickly auditioning how separation sounds. However, one imagines the most common workflow will be to then print each stem onto its own audio track to begin remixing.

There may be some out there who are hoping to use Remix as a real-time live remixing tool – be warned that this is not possible without slight latency and artifacts.

Speaking of printing stems to separate audio channels, Remix makes this process incredibly easy. The plugin has an output for each stem, and if your DAW supports multiple plugin outputs you can set the input of an audio channel as one of these outputs.

This means you can print the stems to their own audio tracks in one go.

Limited stem types

Often when separating tracks which contain just an acoustic guitar and a vocal, Remix will seemingly randomly place the guitar on the Piano and Other channel. The guitar will switch between the two channels as the song progresses making getting a clean guitar stem difficult.

It would have been nice to have more options when it comes to exactly which instrument type is assigned to each stem.

This limited stem type also means that Remix is much more suited to separating stems from rock, alternative and other piano and vocal-based genres than it is say hip hop or dance music.

Not for live remixing

Acon Digital Remix is an impressive and truly cutting-edge stem separation plugin. Being able to perform real-time stem separation and hear parameter adjustments as you make them is a powerful thing.

After spending some time with Remix, one quickly realizes the real power of this technology lies in improving the workflow of those separating stems from mixdowns.

As discussed previously stem separation with other tools on the market is normally a trial-and-error process with a lot of waiting around. Remix streamlines the workflow and makes it much more enjoyable, reducing the amount of time spent sitting and waiting drastically.

Because real-timeline stem separation introduces latency and artifacts to the original track, Acon Digital Remix, unfortunately, does not facilitate distortionless, real-time and on-the-fly live remixing. However it is one step towards this possibility, and with market-leading technologies like this, the first attempt is never going to be perfect.

For those who want to give live remixing a go anyway despite the artifacts and latency, you may be disappointed with the limited controls in Remix. There are no filters, effects sends or panning controls, so remix options are limited to gain adjustments and soloing and muting.

However, these controls are more than adequate for the vast majority of users who will be using Remix for stem separation.

Final thoughts

With Remix, Acon Digital has created something exciting and is a front-runner in the stem separation field. This is truly the beginning of something exciting and I cannot wait to see the possibilities future versions of this technology open up.

There are a few issues, mainly relating to latency artifacts, but this is true of all stem separation tools.

In addition, Acon Digital Remix suffers from limited instrument stem types making it much better at separating stems of specific tracks or genres. That said this is an issue that many of its competitors also suffer from. It would be great to see a market-wide improvement with regard to this issue.

All that said, if you are looking for a stem separator for working in your DAW, Acon Digital Remix is the best option out there right now, and at only £33.90, it is also one of the most affordable.

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