For many of us, paying a mastering engineer to get our tracks over the finish line is out of scope and out of budget, or maybe you just want to apply some level of polish to your productions before sending them out to record labels. Either way, mastering is a tricky process to perfect, and blowing a load of cash on a suite of expensive mastering plugins might be out of the question while you’re only starting out on your mastering journey.
Here at Plugin Boutique, we have an entire section dedicated to free plugin effects, ideal for those on a budget or just trying to see what’s available. It’s an extensive list rather than an expensive list, so we’ve rounded up the best of the bunch for mastering purposes, categorised by the tools you’re likely to need the most.
Free EQ Plugins for Mastering
AudioThing - Blindfold EQ
This simple plugin from AudioThing really lends itself to shaping the tone of your master, with just four bands of EQ and the lack of a frequency readout, you’re forced to use your ears when applying EQ. The Low and High bands are basic shelving EQs, with only gain controls, while the Low Mid and High Mid frequencies are sweepable, with Q control. The bonus Soft Clip and Analog switches are a great way to add some more colour and character to your signal.
HOFA 4U+ - DynamicTiltEQ
HOFA is a German plugin developer with a broad offering of uniquely-featured plugins. One such plugin is 4U+ DynamicTiltEQ, which does exactly what it says on the tin. This plugin is designed to make tonal changes to your entire signal with tilting or shelving curves. There’s also the ability to apply high and low cut, and you can even make your low and high bands dynamic if you wish. Add to that mid/side processing and 32x oversampling, it’s no wonder HOFA brand this as “The best free tilt EQ on the market today”.
Free Plugins for Stereo Widening
Polyverse - Wider
On the face of it, this plugin is the simplest on the list with only one control. Behind the scenes though, Wider uses a clever array of all-pass and band-pass filters to turn a mono signal into a stereo signal, or to turn an already-stereo signal into an even wider signal. Where many stereo enhancement plugins fall is their lack of mono compatibility. Wider promises that it doesn’t suffer with the same ailment, as when collapsed into mono, the stereo widening cancels itself out to leave your signal in phase and intact.
A1Audio - A1StereoControl
If you’d like your stereo widening tool to have a few more buttons and dials, then maybe A1Audio’s A1StereoControl is the plugin for you. A1Audio have also addressed the risks associated with stereo widening, and have developed a ‘Safe Bass’ algorithm that ensures your signal remains completely mono-compatible below the frequency that you set it at. StereoControl’s Expert Mode gives you even deeper control, and adds a selection of pan laws and pan curves, so you can tailor your stereo widening process to your exact needs.
Free Analysis and Metering Plugins
Melda Production - MLoudness Analyzer
While not the most glamorous plugins on the market, analysis tools are a crucial weapon in any esteemed mastering engineer’s arsenal, particularly when it comes to loudness. Melda Production have an immense catalogue of plugins, including a 37-strong bundle of completely free plugins, which MLoudness Analyzer comes with. Check your master’s loudness against a range of measures and standards, and view your waveform with the handy signal visualisation window. As with all Melda plugins, there are a ton of customisation options and the GUI window is completely resizeable.
Blue Cat - FreqAnalyst
Blue Cat is yet another developer with a freeware bundle worth having in your arsenal. FreqAnalyst is available as part of their Freeware Plugins Pack II, and gives you a real-time visualisation of your audio signal’s spectrum. Their unique smooth interpolation algorithms make it an extremely accurate and high-resolution analysis tool. There are mono, stereo and left/right modes, adjustable GUI size and customisable skins, and the threshold control and spectrum zoom let you focus on the really important parts of your signal.
Free Saturators and Enhancers VSTs for Mastering
Klevgrand - FreeAMP
Here we have another simple but effective plugin, this time in the form of a sleek saturation device that fuses the algorithms from Klevgrand’s more complex big brother, REAMP. The result is a style of colouring that resembles both tube and tape saturation. The Drive control lets you add anything from subtle flavour to gritty distortion, while the Mix amount lets you blend in your effect to taste. There’s also an Output level control and output meter, meaning you can match your levels pre and post the plugin to ensure you’re making the right mastering decisions at all times.
ChowDSP - CHOW Tape Model
Despite it being a relatively senior medium of recording music, many people are fond of tape and its ability to add interesting colour and warmth to audio. Tape isn’t the most practical or accessible recording method for most, but ChowDSP have a remedy for that in their free Tape Model plugin. The Wow, Flutter, Loss, Degrade and Chew controls lend themselves to adding a lo-fi feel to tracks, but the Tape and Tone controls are what make this plugin a useful mastering tool. Based on the Sony TC-260 tape machine, Tape Model can add more subtle warmth and colour to your signal while taming transients in a pleasant and musical way.
Free Mastering Limiters and Clippers
Initial Audio - Clipper
Clippers are popular tools in mastering, and are often used instead of or alongside limiters. Soft clipping a signal with a clipper tends to change the character of a signal more than the more transparent limiter, which can be desirable in some instances. This simple clipper’s real-time Peak Display makes it easy to see how it’s affecting your signal, and there’s an inbuilt LUFS meter for checking the loudness of your master. There’s also an inbuilt Saturation control, in case you want to add even more colour to your signal.
LVC-Audio - ClipShifter
While ClipShifter looks quite different to Initial Audio’s offering, both plugins are designed for bringing the level of your master up with some control over the tone and character of the signal. ClipShifter offers everything from gentle saturation to extreme brickwall limiting, so you can tailor your processing to the needs of the master. The unique Dynamic Control functionality lets you process the transient and body of your signal independently; a feature with huge mastering applications. You can even alter the shape of the clipping using the Clip Shape dial. Advanced metering tools round off this plugin and make it a worthwhile download when it comes to dynamic processing at the mastering stage.
VladgSound - Limiter No6
This interesting-looking plugin is both a clipper and a limiter, plus a compressor, all rolled into one feature-packed device. With its serial dynamic processing architecture, mid/side processing, five limiting Types, and 4x oversampling, Limiter No6 is a one-stop-shop for your dynamic processing needs. There’s even a High-Frequency Limiting stage, for taming piercing and sibilant frequencies without impacting the rest of the signal. While that might all sound like too much, each stage of the plugin is able to be switched on and off, so you can apply only the processes you really need.
Free Plugin All-Rounders for Mastering
HOFA - System Basic
HOFA’s second appearance on this list comes courtesy of their System Basic channel strip. It’s essentially a streamlined version of System, their comprehensive channel strip plugin. Despite being a trimmed back version of a bigger product, System Basic still contains 29 plugins, which can be routed in whichever way you need. Your own unique plugin chains can then be saved for use in future projects, a particularly useful tool when mastering projects with multiple tracks. The included plugins include all the tools you’ll need to master a track and more, including EQ, compression, metering and gain plugins.
Kilohearts - Essentials FX Bundle
Kilohearts are renowned for having some of the most powerful plugins on the market (just look at their flagship synth, Phase Plant). Their Essentials bundle is no exception, and includes an assortment of plugins that can be used throughout the entire production process, including during mastering. As with HOFA’s System Basic, you get all the essentials, including EQ, Compression, Distortion, Dynamics and Limiter. Add to that some more specific tools which cover transient shaping and stereo enhancements, and the Essentials FX Bundle might be the only thing to need in your mastering toolbox. The plugins can even be used in a modular format by pairing them with any Kilohearts Snapin-enabled plugin.