FabFilter Pro-Q 4 Review: Is It Still a Thing?

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Ten years ago, Pro-Q set the standard for what a modern EQ plugin should look like and feel like. Every major EQ released since has been compared to it in some way, which is either a compliment to FabFilter or an indictment of how slowly the category moves. Pro-Q 4 is the latest version, and the question worth asking isn’t whether it’s good. It is. The question is whether the updates justify it still being the default recommendation in a market where strong alternatives now exist at lower price points.

I’ve used FabFilter Pro-Q 4 across mixing, mastering, and sound design sessions, and my honest assessment is that it earns its position, but for more specific reasons than “it’s the best EQ.”

Band architecture

Pro-Q 4 supports up to 24 bands across the full frequency spectrum with 9 filter shapes per band covering bell, shelf, high-pass, low-pass, notch, band-pass, tilt, flat tilt, and the new Brickwall filter that provides extremely steep attenuation for mastering applications where surgical frequency removal is required. Each band operates in stereo, left/right, or mid/side mode independently, which means you can apply different EQ curves to the mid and side channels within a single instance without additional routing.

I find the per-band channel mode the most practically useful addition for mix bus and mastering work. Being able to cut the low-mid mud from the mid channel while boosting the sides at the same frequency simultaneously in one instance is faster than any alternative approach I’ve used, and the visual feedback makes those adjustments intuitive.

Here’s what the band architecture gives you:

• Up to 24 bands with 9 filter shapes per band including the new Brickwall filter for mastering applications
• Per-band stereo, L/R, and M/S processing within a single instance, eliminating the need for separate mid-side routing
• Natural Phase, Linear Phase, and Zero Latency modes selectable per band, giving you phase coherence where you need it without paying the latency cost across the entire EQ
• Dynamic EQ mode per band with adjustable threshold, ratio, attack, and release, turning any static EQ band into a frequency-specific dynamic processor
• Auto gain compensation that adjusts the output level as you add bands, keeping the comparison between processed and unprocessed signal honest

Dynamic EQ

Every EQ with a dynamic mode isn’t created equal, and this is where Pro-Q 4 pulls ahead of most competitors. Each band’s dynamic mode adds a threshold, ratio, attack, and release that make the band respond to the signal level in that frequency range specifically. I use this most on mix bus low-mid control where certain chords and notes push that frequency range harder than others, and a static cut would thin out the mix on quieter passages where the buildup isn’t happening.

Setting a low-mid band at 250 to 350 Hz with dynamic mode, a 2:1 ratio, and a moderate threshold produces transparent frequency-specific compression that a static EQ can’t replicate and a multiband compressor handles with less precision. If you’ve been reaching for a multiband compressor for that application, this is worth trying first.

The external sidechain feeds a separate signal into the dynamic band’s detection circuit, and combined with the M/S per-band mode this opens up advanced frequency-specific ducking and de-essing workflows within a single EQ instance.

Spectrum analyzer and collision detection

Spectrum Grab lets you click directly on a frequency peak visible in the analyzer and drag it down without manually placing a band first. I find this genuinely faster on dense sessions where identifying problem frequencies visually and correcting them is a single gesture and not a 2-step process.

EQ Match analyzes a reference track and generates an EQ curve that moves your signal toward the spectral balance of the reference. I use it as a starting point on mastering work and not a finished result, because the match curve gives you a useful frequency map of the gap between your mix and the reference, and from there you make the musical judgment calls about which parts of that map to follow.

What’s new in version 4 is the Collision Detection feature, which shows you where the frequency content of different tracks in your session is competing. You load Pro-Q 4 on multiple channels, enable the collision view, and the analyzer highlights frequency ranges where those channels are masking each other. I find this most useful on competing mid-range instruments like guitars and synths where the overlap isn’t immediately obvious by ear but is causing the mix to feel dense and unclear.

• Spectrum Grab

Click directly on a frequency peak in the analyzer and drag it down without placing a band manually. On sessions with obvious resonances or problem frequencies, this removes a step from the correction workflow and makes the whole process feel more tactile.

• EQ Match

Analyzes a reference track and generates an EQ curve toward that spectral balance. I use it as a starting point on mastering work, treating the generated curve as a frequency map of where my mix differs from the reference and making selective adjustments from there.

• Collision Detection

Shows where frequency content from different tracks is masking each other across the session. Loading Pro-Q 4 on multiple channels and enabling the collision view highlights the competing frequency ranges, which is most useful on mid-range instruments where the masking isn’t obvious by ear.

Phase modes and latency

Zero Latency, Natural Phase, and Linear Phase modes are selectable per band, not just globally, and this distinction matters more than it might seem. Running the low bands in Natural Phase for transient preservation while switching the high bands to Linear Phase for phase coherence on surgical cuts is a more precise approach than a single global phase mode forces you into.

Linear Phase mode eliminates phase shift but introduces latency and pre-ringing on transient-heavy material. I’d use it selectively on mastering chains and surgical notch cuts where phase coherence matters, and keep Natural Phase as the default on everything else. At higher oversampling settings, the processing gets noticeably heavier on CPU, so it’s worth managing the oversampling rate on sessions where multiple instances are running simultaneously.

Preset library

Pro-Q 4 ships with over 100 factory presets organized across 8 categories covering Mastering, Mix Bus, Vocals, Guitars, Bass, Drums, Synths, and Corrections.

Each category addresses the most common EQ requirements for that application, and I find the Corrections category useful as a reference for how to configure the dynamic EQ bands for common problems like sibilance control, low-mid buildup, and proximity effect reduction on recorded vocal material.

The Mastering presets demonstrate the Brickwall filter and Linear Phase band mode configurations most clearly, and I’d recommend loading a few of those before building mastering chains from scratch, because they show you how the per-band phase mode selection is intended to work in a professional mastering context and save you the time of working that out through trial and error.

The preset system saves every aspect of the EQ configuration including phase mode per band, dynamic band settings, threshold, ratio, attack, release, and M/S channel assignments per band. I use this most on sessions where I’ve built a complex multi-band dynamic EQ setup that I want to apply consistently across multiple tracks without rebuilding from scratch each time.

The EQ Match result is also saveable as a preset, which lets you build a library of reference-matched curves for different genres and mastering targets over time. I’ve built a set of 12 to 15 genre-specific starting point presets from EQ Match sessions against well-mastered references, and having those available at the start of a new mastering session accelerates the process considerably when you have a clear sonic target in mind.

The browser supports text search and category filtering, and finding a relevant starting point on a new session takes under a minute. That said, if you primarily work from presets you’ll exhaust the useful factory content faster than you might expect, and building your own collection through saved sessions and EQ Match results is where the preset system becomes genuinely valuable over time.

Applications

For mixing, the combination of dynamic EQ per band, per-band M/S processing, and Spectrum Grab produces a workflow that’s genuinely faster and more precise than assembling the same capabilities from separate plugins. You won’t need a separate dynamic EQ, a separate mid-side EQ, and a separate spectrum analyzer on the same channel.

Obviously, for mastering, the Brickwall filter, Linear Phase mode per band, and EQ Match give you the technical tools that mastering work requires, and the precision of the 24-band architecture suits the surgical frequency management that mastering chains demand.

Where it’s less relevant is on quick, simple EQ tasks where a 4-band channel strip EQ gets you to the result faster without loading a plugin with this much depth. Pro-Q 4’s value scales with the complexity of the frequency management you need to do, and on straightforward EQ applications you’re paying for capabilities you won’t use.

Pros:

• Per-band M/S and L/R processing

Applying different EQ curves to mid and side channels within a single instance eliminates mid-side routing overhead and makes the visual feedback of the adjustment immediately clear. I use this consistently on mix bus and mastering applications where mid-side frequency management is a regular requirement.

• Dynamic EQ per band

Frequency-specific dynamic control with threshold, ratio, attack, and release per band produces transparent frequency management on complex material that static EQ can’t replicate. On mix bus low-mid control specifically, this produces results that a multiband compressor handles with less precision.

• Collision Detection

Identifying masking between tracks visually across the session is a workflow improvement that no other standard EQ plugin offers as directly, and it produces more informed EQ decisions on dense mixes where the masking isn’t obvious by ear.

Cons:

• Price versus alternatives

At $199, Pro-Q 4 competes with strong alternatives from DMG Audio, Fabfilter’s own history, and free options like Voxengo Marvel GEQ that cover straightforward EQ applications competently.

The price is justified if you use the dynamic EQ, collision detection, and per-band M/S processing regularly. If you primarily use static EQ, the cost is harder to justify.

• CPU at high oversampling

Running multiple instances in Linear Phase mode at high oversampling is noticeably heavy, and on larger sessions you’ll need to manage the oversampling rate actively to keep the CPU load manageable.

Verdict

Pro-Q 4 is still a thing, and I’d say it’s earned that position through specific technical capabilities and not just brand reputation. The per-band M/S processing, dynamic EQ per band, Collision Detection, and Brickwall filter address real mixing and mastering problems with a precision and workflow speed that most alternatives don’t match in a single plugin.

If you primarily do straightforward static EQ work, the price is harder to justify and simpler alternatives cover that ground at lower cost. But if dynamic EQ, mid-side processing, and frequency collision analysis are part of how you work, Pro-Q 4 remains the most complete single EQ plugin available, and the version 4 updates add enough practically useful capability that the upgrade from version 3 is worth considering if those features fit your workflow.