bpb Freeware Studio: Best Free Linear-Phase EQ VST/AU Plugins

Today’s edition of bpb Freeware Studio features a selection of the best free linear-phase equalizers in VST/AU plugin format for Windows and Mac. You might also want to check out previous articles covering free parametric EQs and free graphic EQs.

If you’re wondering about the concept behind linear-phase EQs, here’s a little introduction. Basically, minimum-phase EQs (aka IIR or infinite impulse response – the ones you use every day) are causing a phase delay of the frequencies you’re boosting/cutting, which results in audible artifacts (often described as smearing) due to the phase difference between the affected and unaffected parts of the signal.

These artifacts become more audible as you further increase/decrease the gain. On the other hand, linear-phase filters (aka  FIR or finite impulse response) will delay the whole signal by the same amount so that all frequencies are kept in-phase, but this results in added latency and pre-ringing artifacts (with minimum-phase EQs we get post-ringing which we usually don’t hear since it’s masked by the actual audio signal). So which is better? There is no clear answer to that question – as you can see, both come with certain advantages and drawbacks! Your best bet is to take some time to practice, listen carefully to the results and decide for yourself which tool to use in given situations.

For some further reading on topic of different EQ types, I recommend this useful article by MeldaProduction, and Roey Izhaki’s awesome Mixing Audio book (here’s the part covering linear-phase equalizers). Ok, school’s over – time to play with some freeware VSTs!

Filtrate LE is my go-to linear-phase EQ. The interface is pretty much what you’d find on a regular parametric equalizer and that’s what makes it so easy to work with in my case. Filtrate LE is the free version of Filtrate, featuring 5 frequency bands (you can switch between bell, shelf, and LP/HP curves). Those with NVIDIA 8 Series GPU (and above) graphic cards can use the GPU Edition and give their main CPU some slack.

ReaFIR is a brilliant plugin released by Cockos, part of their free VST plugin bundle. Once you engage the Reduce artifacts button, ReaFIR begins to operate in linear-phase mode. To learn more about the way this plugin works, check out the ReaFIR article on CockosWIKI.

Marvel GEQ is another great free linear-phase EQ with some unique features. It’s a 16-band linear-phase graphic equalizer with stereo and multi-channel processing, as well as mid/side processing capabilities! To check out the full feature-list, click here.

SplineEQ is an amazing linear-phase equalizer recently released by Photosounder (the free version is limited to 4 bands). The main twist with SplineEQ is that it uses Bézier curves, which undoubtedly results in a different sound character compared to other EQs. I’m kinda still practicing with this plugin trying to get familiar with how it works, but I like it more and more every day!

Finally, LinearPhaseGraphicEQ 2 and Glacier are two older linear-phase EQs, but worth checking out nevertheless. Glacier is a 1-band design, which can be pretty useful if you just need to perform a quick cut/bosst without hassle.

Before you go, here’s a nice video by MacUpdate, explaining some of the concepts behind SplineEQ:

And that’s pretty much all for today. If I’ve missed mentioning a good linear- phase EQ, feel free to suggest it in the comments section below. Also, please help BPB grow by sharing links to this and/or your other favorite BPB articles! Thanks for reading and have fun mixing!