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Magix ACID Pro Next

Loop-based Production Software For Windows By Robin Vincent
Published August 2019

Magix ACID Pro Next

ACID Pro is the original loop-based remixing program, and the Next version opens up new possibilities thanks to the intriguing Stem Maker.

When it first appeared in the late '90s, ACID's extraordinary ability to manipulate the pitch and tempo of looped audio created a whole genre of computer-based loop sequencing that had previously been the realm of scratch DJs and hardware samplers. Loops in ACID contained tempo and key information that allowed them to be matched automatically when used in the same project. Armed with a sample CD of 'Acidized' loops, you could paint them onto a timeline and pull together arrangements at great speed.

This looping technique has been adopted by pretty much every audio production program since. The ability to pitch-shift audio and time-stretch loops to fit a given tempo is a standard feature and one for which Ableton Live was invented. ACID, meanwhile, slowly acquired the vital bits and pieces it needed to call itself a DAW, and by version 4 in 2003 had MIDI sequencing, automation, VST plug-ins, surround–sound mixing and video support. It was around this time that the original makers Sonic Foundry sold everything to Sony, and for the next decade or so, Sony seemed to put most of their effort into developing the Vegas Pro video editing software that had emerged from ACID in 1999. ACID crawled to a couple of new versions, but development had largely stalled. When German software developers Magix picked it all up from Sony in 2016, they had a lot to do to breathe life back into this loop–making workstation.

Last year saw the release of ACID Pro 8, the first update to the program in many years, with a slightly updated look, 64-bit coding and support for VST3 plug-ins. It was what they needed to do to get ACID back on track, but was very much a statement of intent rather than anything new or innovative. Now, however, Magix are opening a new chapter in the history of time-stretching with ACID Pro 9 and ACID Pro Next. Quite why these need separate names is unclear, but perhaps Magix have diverging plans for the brand. At the moment ACID Pro Next has all the features of ACID Pro 9 plus a small number of extras. Each update usually brings with it large barrels of loop content, too, and this update certainly doesn't disappoint.


For this review, I'll focus on the new features found in ACID Pro Next, but first, a word or two about installation. I'd usually skip past this part in a software review, but I found the process so infuriating that I thought it deserved mention, in the hope that Magix will sort it out for future installers. The problem is that installer doesn't let you specify where the 24GB or so of library content should go, and so it fills up your C drive, first with the downloaded files and then with the installed content. ACID doesn't tell you where it lives or how to find it, and the manual and tutorial videos came up empty. I scoured the forums and came across a helpful post which directed me to a folder called Loop Collections in Local Disk C:\Users\Public\Public Documents\MAGIX\Common. Hooray! After moving them to a sensible drive I could then use my system again. The installer also places several gigabytes of sample content for Magix's VITA instrument on the system drive, but if you move this, the instrument won't open (sigh). This has nothing to do with the functionality of the software, but these days, it's disappointing that there isn't a more sophisticated content installer. It meant that I started this review — as any user would — with several big bags of frustration.

The Heart Of ACID

If you like to make music by painting loops onto a multitrack timeline, nothing else does this in quite the same way or as quickly as ACID. Browsing through the extensive library of loops and dropping them onto a track and having them work perfectly every time is a happy way to play. Auditioning loops is automatic and they're always in time and always in tune. And you do paint with loops, rather than place them or copy and paste them. Once a track has a loop attached, that loop appears wherever you click the paint tool in that track. With a few clicks you can flesh out arrangements in seconds, on the fly.

Any imported ACID loops will automatically shift themselves into the project's key, and individual tracks or clips can be manually shifted up and down in pitch by hitting the plus and minus keys. When arranging a song, you can create 'sections' to group tracks along the timeline into something like a verse and chorus structure. You can then pitch-shift entire sections to create chord progressions or key changes.

ACID also has a very fruity Groove engine, which was the one awesome feature Sony added to the mix. You can pull a detected groove from any audio loop and apply it to another one, or you can create your own grooves by swinging the beat markers about. When you apply it to a loop in the timeline, a groove track appears where you can paint in parts of the groove along with parts of other grooves to find the exact sort of swing you're after.

Alongside this incomparable looping and grooving engine are the usual trappings of a DAW. You have multi-channel audio recording, software synthesizer and audio plug-in support, automation, a mixing console and support for surround sound. There are some neat aspects, like being able to chain audio effects onto individual clips as well as the track, and automatic crossfading. But most of these features have been there since version 4 with Sony adding the Groove engine in version 5. Since then it's been mostly new loops — until now. What can Magix bring to the table in ACID Pro Next?

MIDI Playable Chopper

The Chopper is ACID's loop slicer and was introduced in version 4. Send a loop to the Chopper and ACID will slice it up and let you pull out slices or selections of slices to use as one-shots or new loops on your timeline. What the MIDI implementation means is that each slice is mapped to a note on your MIDI keyboard and becomes playable in an MPC or ReCycle style. (In fact, the name MIDI Playable Chopper is, apparently, a nod to the MPC sampler.) Any Acidised loops will already have marker information imprinted on them and so when you send them to the chopper you can play the slices on your keyboard immediately. Other loops will require you to drop markers on where you'd like the samples to start. It's quick, fun, effective and instantly turns loops into playable MIDI instruments.

The MIDI Playable Chopper divides up a  loop into rhythmic elements and assigns them to MIDI notes for triggering, providing a  simple and effective way to re-groove a  beat.The MIDI Playable Chopper divides up a loop into rhythmic elements and assigns them to MIDI notes for triggering, providing a simple and effective way to re-groove a beat.

You can write a MIDI sequence to address the Chopper, but it can be easier to stay in the world of audio hits and loops. If you delete the original loop from the timeline, you can then insert the played slices back onto the track as chunks of audio. Enable the Chopper for MIDI recording, set your project into record and the slices will appear on the track as you play them with your keyboard. It's instant audio remixing.

A similar sort of functionality used to be available in the VITA Sampler virtual instrument, but seems to have been retired in favour of this more integrated approach. It's a job that traditional samplers handled with aplomb but which is often made overcomplicated in software. The MIDI Chopper is precisely like a hardware sampler, which makes it so quick and easy to remix and play with bits of audio. It reminds me of the playlist editor in Sound Forge, which I've used a lot for cutting a full-length piece of music down to a smaller sound bite — except that rather than creating a playlist of markers, you can achieve the same remixing results with MIDI notes in the timeline.

Stem Maker

Whereas the MIDI Playable Chopper is included both in ACID Pro 9 and Next, the biggest new headline feature is the Stem Maker, exclusive to Next. Unfortunately, both versions come with the manual and help files for Pro 9, so there's no instructions or guidance for using Stem Maker, but with a bit of intuition and some YouTube videos, I think I've got the measure of it.

What Stem Maker does is break down mixed tracks into three stems: one for drums; one for vocals and one for everything else. You'd be forgiven for believing it was even more advanced than that, because the marketing very much implies that the source is split into 'component' tracks; that's not quite the case, but it's still extraordinary.

Stem Maker is an applicaton of Zynaptiq's audio source separation technology, which uses DSP algorithms based on deep learning to split the tracks into vocals, drums and music stems. So, what does it sound like? Well, it sounds a lot like you'd expect it to sound. There are a lot of artifacts. Reverb tails spill over from instruments into the vocals, algorithmically crushed splashes and cymbals pop up unexpectedly, and the music section seems full of ghostly vocals and drums that sound like they do when you're standing in the toilets at a gig. I tried lots of different source material, from Queen and Talking Heads through to Leftfield, Gorillaz and Taylor Swift, and my expectation of a miraculously clean extraction never really materialised. But that's because my expectation was wrong: what Magix and Zynaptiq are offering here is not the perfectly rendered vocal track from a mixed song, but the tools to remix and sample elements from mixed songs — and to do it with a few minutes of processing, rather than having to spend hours manually phase inverting, EQ'ing and filtering the pieces you want to drop into your own track. The reality is that you can pull drum samples, loops and vocal phrases from places in tracks where you have no business taking them.

The Stem Maker in action: here, I've separated Iggy Pop's 'Lust For Life' into vocal, drums and music stems, and I  have a  section of the vocal track selected in the Chopper.The Stem Maker in action: here, I've separated Iggy Pop's 'Lust For Life' into vocal, drums and music stems, and I have a section of the vocal track selected in the Chopper.

Stem Maker runs as an importing process, allowing you to bring a song into ACID and then break it into individual parts; you can't apply it to existing tracks or samples on your timeline unless you first export them as stereo audio files and then use Stem Maker to bring them back in. Once you've selected a file, the Beatmapper tool appears, asking if you want to detect the tempo of the song so that it can fit nicely with your existing project. You give it a hand by adjusting a couple of markers and then it's ready to do the intelligent audio source separation. It seemed to take around 10 minutes to process a three-minute song. Once done, you have a track containing the original song plus three new tracks with the vocals, drums and music stems.

At this point, you can start scanning through the tracks and picking out sections to throw into the MIDI Playable Chopper — and that's why it works. It's the combination of the Stem Maker and the MPC that forms a workable and useful process. Perfectly clean samples are few and far between, but with a bit of further tweaking and careful cutting or marker placement, decent, usable samples can be found.

I am warming to the whole idea now that I've built a convincing duet out of David Byrne's and Julie London's voices, with drum samples from 'And She Was', 'Lust For Life' and some song by the 1975. But I am still doubtful about the usefulness of the music track, which sounds very weird indeed. Perhaps there's something there for the karaoke market? The source material does of course, matter: Stem Maker was able to pull a decent vocal track out of Julie London singing 'Fly Me To The Moon' but the light jazzy drums were totally demolished. Experimentation is the key, and once you start having a go, you'll find yourself losing hours in the pursuit of samples.


In many ways Stem Maker builds on the essence of ACID. It's a remixing tool, perfectly adapted to pulling loops out of everything and letting you mess them about into your own grooves. Bringing MIDI to the Chopper was a stroke of obviousness that gives ACID a new creative avenue to wander down and is perfectly matched to the allure of Stem Maker. I've discovered that breaking apart songs to mine them for samples is rather addictive.

The plethora of different versions (see box) seems confusing and feels unnecessary. It also means that some upgrade paths seem a lot more worthwhile than others. For example, existing ACID Pro 8 users have got to pay £79$149 to upgrade to version 9, but the only key new feature they'll receive is the MIDI Playable Chopper. The Stem Maker is such a remarkable feature, and so germane to ACID's core functionality, that I think it should be in the default version — perhaps Magix should dump version 9 altogether and restart the range with ACID Pro Next, make that the £79$149 upgrade version, and watch how quickly everyone jumps on it. As it is, to upgrade to Next from ACID Pro 8 you'll need to come up with £249$299, which is likely to put quite a few people off.

Ultimately, though, ACID Pro Next could be the version that brings ACID back into the game. It needs a bit of polish in places and some fixing in others — a manual for this version would be a good start — but Magix have pulled a feature out of the bag that'll tempt a lot of people into downloading the trial at the very least. And while it's not exactly what you imagine it could be, it is an awful lot of fun.

Other New Features

As well as the headline features, ACID Pro Next (but not Pro 9) provides a new loudness meter, which appears on the master channel and on individual channels of the mixing console. Melodyne Essential is now included (as a conventional plug-in — ARA is not implemented), perhaps acknowledging the ways that pitch-shifting technology has developed since ACID was launched. And, as always, ACID Pro comes with a huge bundle of loops and additional sound library content for the VITA 2 software instrument. A handful of decent modern-looking effects have also been added to complement the existing Windows 98-style classics from the Sonic Foundry days.

Flavours Of ACID

There are currently five different versions of ACID Pro available. In some cases the differences are small enough to make you wonder why Magix thought them worth creating — but the price differences are quite striking. ACID Pro 9 (£129$149) and ACID Pro 365 (£5.99 per month$7.99 per month) both lack the Stem Maker, Melodyne and loudness meters. The 365 version, which is sold on a subscription model, has a couple of extra plug-ins and some more VITA library content as a sweetener over buying ACID Pro 9 outright. ACID Pro Next for an extra £170$250 then picks up the swanky new Stem Maker, Melodyne and Loudness features. It has the same library as ACID Pro 365 but picks up some mastering plug–ins. ACID Pro Next 365 (£10.99 per month$13.99 per month) scores a little bit of extra library and one plug-in, and the top-of-the-tree ACID Pro Next Suite gets a good chunk of library, a bunch of plug-ins and the Independence Pro Plus Suite instrument bundle for another £150$200. (All prices include VAT.)


  • Stem Maker will get you addicted to mining samples.
  • MIDI Playable Chopper is a simple and effective implementation that works really well.
  • The core ACID program still offers the best approach to loop-based composition.


  • Apart from the Stem Maker and MPC, most of the other core features are now quite old.
  • Complicated version structure, with no affordable upgrade path to the Next version.
  • Installer forces you to place loop content on the system drive.
  • No manual for the Next version yet.


ACID Pro Next pulls an intriguing new feature out of the bag while reminding everyone of its virtues as a tool for loop makers and remixers.


See 'Flavours Of ACID' box.