If you’ve ever struggled to make a vocal sit cleanly on top of a busy instrumental, you’ve probably wished for a smarter alternative to sidechain compression. That’s exactly the problem spectral ducking solves, and for years, Wavesfactory’s TrackSpacer has been the go-to tool for the job.
But TrackSpacer costs $59. And until recently, there wasn’t a serious free alternative.
That’s changed.
Two completely independent projects (one from a solo developer, the other from a university lab) have released free plugins that bring spectral ducking to anyone with a DAW.
Let’s talk about what this technique actually does and whether these two tools can replace TrackSpacer.
What Is Spectral Ducking (And Why Should You Care)?
Standard sidechain compression is a blunt instrument. When the kick hits, the entire signal ducks, including the bass, mids, highs, everything.
It works for obvious pumping effects, but it’s a bit clumsy when you need surgical separation between two elements that occupy similar frequency ranges.
Spectral ducking takes a completely different approach.
Instead of compressing the whole signal, it analyzes the frequency content of a sidechain source and applies an inverse EQ curve to the target track in real time. Only the frequencies that actually clash get reduced, and everything else stays untouched.
The difference is huge. You get a much cleaner and more transparent separation. And this solves a bunch of mixing pet peeves.
You can have your vocals cut through guitars without the guitars disappearing. Or, have the bass synth make room for the kick without losing its top-end presence.
This is what separates polished mixes from muddy ones.
TrackSpacer essentially pioneered this as a dedicated plugin category. It uses a 32-band internal EQ that reacts to the sidechain signal, with controls for attack, release, and frequency filtering.
It’s simple to use and delivers excellent results. The catch was the price tag and the fact that nothing free came close.
Well, until now.
It’s worth noting that TrackSpacer isn’t the only paid option. Plugins like Techivation M-Blender, Sonible’s smart:comp 2 and pure:unmask, Waves Curves Resolve, iZotope Neutron’s Unmask module, and UnitedPlugins VoxDucker all offer some form of spectral ducking, either as their main feature or as part of a larger toolset.
But most of these cost between $59 and $199, which makes the two free alternatives below even more interesting.
ANINA by Ewan Bristow (February 2026)
If you follow BPB, you might remember Florah Lite, a free spectral shaping plugin that Ewan Bristow released in November 2024.
It was a promising free alternative to TrackSpacer, but it came with a caveat: it required PlugData to run. And that extra step was a dealbreaker for many of our readers, as you can see in the comments on that article.
ANINA is Bristow’s answer to that feedback. Released on February 20th this year, it’s a proper standalone plugin available in AU, VST3, and CLAP formats for macOS, Windows, and Linux.
And it doesn’t require PlugData.
But ANINA isn’t just Florah Lite repackaged as a plugin, either. It’s an upgrade across the board.
The plugin offers up to 1024 bands of compression (compared to TrackSpacer’s 32), low and high filter-signal cutoff controls, and a sidechain input for carving space exactly where it’s needed in your mix.
It also has a real-time visual display that shows the input and filter spectra, so you can see precisely what the plugin is doing.
The three main parameters (Attack, Amount, and Release) control the spectral curve’s behavior. Attack adds transient emphasis to the curve, Amount controls the depth of reduction, and Release adds decay.
The adjustable block size parameter lets you trade between tighter timing response and better frequency resolution.
I also like ANINA for its sound design capabilities. The Freeze button locks the filter spectrum in place, so you can use a captured spectral fingerprint as a static processing shape.
The Delta function lets you hear what the plugin removes from your signal, effectively turning it from a resonance suppressor into a resonance isolator. The results can get wonderfully weird.
If you dismissed Florah Lite because of the PlugData requirement, ANINA removes that barrier entirely. And for all producers looking for a free TrackSpacer alternative that also doubles as a creative sound design tool, it’s the best option right now.
TheMasker by LIM (March 2024)
TheMasker was developed by students at the Laboratory of Music Informatics (LIM) at Milan University in Italy, as part of the “Development of Technologies for Music Production” course.
Yes, it’s a student project, which I think is pretty cool in itself.
TheMasker is a frequency-masking compensation plugin that, when you boil it down, does exactly what TrackSpacer does: it analyzes a sidechain signal and applies dynamic EQ corrections to the target audio to attenuate overlapping frequencies.
The workflow is straightforward. You load it on the track you want to reveal in the mix, route the masking instrument to the sidechain input, and let the plugin handle the rest.
It provides a clear visualization of the input signal (white), sidechain signal (yellow), and the purple Delta display showing which frequencies are being affected and by how much.
The Sidechain Level control adjusts the incoming sidechain volume for fine-tuning the effect. You can choose to Bury or Reveal either the Masked or Clear frequencies (typically, you want to bury the masked frequencies and reveal the clear ones).
The Clean Up slider controls the width of the affected frequency range, and the AMT knob blends the processed signal in parallel.
Being a university project, TheMasker comes with a caveat: it’s technically still in beta, and the developers don’t guarantee stability.
Some of our readers have reported minor issues with certain DAWs (particularly FL Studio, where enabling “fixed-sized buffers” in the wrapper settings resolves distortion). It’s also worth noting that on macOS, you may need to manually approve the plugin in your security settings since it’s unsigned software.
That said, it works. The spectral ducking is effective, the visualization is helpful, and the price is hard to beat.
How Do They Compare to TrackSpacer?
TrackSpacer remains the most polished option in this category. It has the cleanest interface, the most reliable cross-DAW compatibility, mid/side processing, and the stability you expect from a mature commercial product.
| Feature | TrackSpacer (Wavesfactory) | ANINA (Ewan Bristow) | TheMasker (LIM) |
|---|---|---|---|
| Price | $59 | Free | Free |
| Processing Bands | 32 | Up to 1024 | Dynamic / Continuous |
| Formats | VST, AU, AAX | VST3, AU, CLAP | VST3, AU |
| Best For | Polished, zero-friction pro mixes | Deep tweaking & creative sound design | Quick unmasking |
| Cons | The price tag | ~11ms latency (spectral processing) | Beta software |
But the gap has narrowed.
ANINA arguably offers more raw processing power with its 1024-band compression and sound-design features (Freeze and Delta), which TrackSpacer doesn’t have. It’s the more adventurous of the two free options and great for producers who want spectral ducking plus creative possibilities for sound design.
TheMasker is the more straightforward mixing tool. It does the core job with a simple interface and provides helpful visualization. It’s useful if you just want to solve frequency masking problems without having to think about a lot of extra features.
If you’re on a budget, either of these plugins can handle the fundamental task that made TrackSpacer famous.
And if you’re already a TrackSpacer user, I think they’re still worth downloading. ANINA’s Delta mode alone opens up the creative territory that TrackSpacer doesn’t touch.
The Bigger Picture
It’s worth stepping back and appreciating what’s happening here.
Spectral ducking was, until very recently, a technique locked behind a paywall. Now you have a solo developer shipping a 1024-band spectral processor for free, and university students building research-grade tools and releasing them to the public.
For producers working on a tight budget (or anyone who wants to experiment with spectral processing before committing to a purchase), the barrier to entry has pretty much disappeared.
Read more: TrackSpacer / ANINA / TheMasker
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Last Updated on March 4, 2026 by Tomislav Zlatic.
