Free Mastering Chain

Free Mastering Chain


  1. Subtractive EQ – 2S EQ
  2. Saturation – GSatPlus
  3. M/S Compression – Frontier
  4. Side Image – MSED & Crack
  5. Mid Image – MSED & BUSTERse
  6. Additive EQ – Warmy EP1A
  7. Air EQ – Fresh Air
  8. Collective Compression – Limiter No6
  9. Peak Limiting & Clipping – Limiter No6
  10. Final Limiting – Limiter One

Subtractive EQ – 2S EQ

To start this mastering chain, I’ll use subtractive EQ to attenuate aspects of the mix I want less of – usually in a very subtle way. This 2S EQ by 2nd Sense is a great free parametric EQ, but the scaling is designed for mixing, so keep an eye on how much you’re attenuating each band.

Instead of listening to just this EQ enabled, let’s listen to the full before and after of our chain so we know where we’re headed, and also since this EQ is so subtle it’ll be hard to hear much of a difference after YouTube compresses the audio.

Saturation – GSatPlus

After I’ve controlled some of the frequencies, I’m going to subtly saturate the mix to make it fuller and a little more complex. With GSatPlus, I’ll use the warm algorithm with 2 stages and mild harmonic fluctuation, before increasing the odd and even harmonics.

Also, note that I’ve decided to only saturate the mid-channel – this will add drive and focus to the master, making it more impactful. Lastly, I enabled 2x oversampling to avoid aliasing.

Let’s take a listen to how this subtly fills the sound.

Compression – Frontier

Frontier is a great-sounding plugin, but it can be way too aggressive for a master if not used thoughtfully. I’ll use the mid image as my input, use a fast release, and then very subtly reduce the threshold until I only have a small amount of attenuation.

Since this plugin introduces automatic makeup gain related to the threshold and not the gain reduction, I’ll need to compensate for amplitude changes by lowering my output accordingly.

Let’s listen and notice how the lows in particular become punchier and more aggressive.

Side Image – MSED & Crack

So far I’ve been processing on my channel strip – this gives me the opportunity to create sends that can be combined with my original signal and processed collectively on the stereo output.

For my first send, I’ll use the plugin MSED to mute the mid image, in turn isolating the side image or what’s responsible for the perception of stereo width. Then, I’ll use a transient shaper, in this case, the plugin Crack, to increase the amplitude of the side image’s attack.

This increases the transients of my side image, resulting in a more detailed stereo image. Then I’ll blend this isolated side image back in by using the aux track’s channel fader.

Let’s listen and notice how our track is subtly wider and has more detail on the far left and right.

Mid Image – MSED & BUSTERse

Just like the last chapter, I’m going to create a send and use the plugin MSED, but this time I’ll isolate the mid image by muting the side. Then I’ll introduce the plugin BUSTERse by Analog Obsession and compress heavily with a quicker attack and moderate release.

Afterward, I’ll use makeup gain to increase the level of the heavily compressed signal before blending in these parallel compressed mids by using the channel fader.

This creates a dense mid-image, adding to the power of the master. Let’s listen starting with both the side and mid image sends muted, and then enabling both.

Additive EQ – Warmy EP1A

On my stereo output, I can not collectively process my original signal and my sends – with the Warmy EP1A, a Pultec emulation, I’ll set my low and high filters to 30Hz and 16kHz respectively, before subtly amplifying both filters – both with broader bandwidths or Q values.

I’ll enable oversampling since I amplified my highs, and also keep this mix dial at 0 since it introduces some form of saturation unrelated to the changes made with the EQ itself.

Let’s listen and notice how we get a fuller sound with the 30Hz. filter, and some air with the higher filter.

Air EQ – Fresh Air

Although the high frequencies added by the last EQ sounded good, I want to add a little more using this Fresh Air plugin from Slate Digital. I’ll de-link the mid-air and high-air channels before amplifying them both very subtly since this processor is pretty powerful.

Let’s listen and notice how we can hear more high-end detail, how the master feels more balanced, and how a subtle air is added up top.

Collective Compression – Limiter No6

Limiter No6 introduces multiple forms of processing so I’m going to break up my explanation of it into 2 chapters – first, I’m going to affect the compressor by keeping a very low ratio, a moderate attack, and a faster release. Then, I’ll set the processing to M/S.

Since the mid image will often be louder than the side, more compression will occur to the mids, making the side image relatively louder.

In other words, when compression occurs to the mids, or stereo width will increase.

Let’s take a listen to just this compressor enabled and notice this dynamic relationship between the mid and side image.

Peak Limiting & Clipping – Limiter No6

So again, we’re using the same processor, but this time I’m going to enable peak limiting. What’s great about this limiter is that it can be set to Multi-band, meaning various frequencies will be measured and processed according to their relative amplitudes – resulting in more control and a transparent sound.

I’ve also de-linked the detection, meaning my left and right channels will be measured separately. Then I enabled the high-frequency limiter, which isn’t doing too much, but it’ll control the highs better than just the peak limiter alone.

In the clipper section, I’ve lowered the threshold to engage the processing and set the mode to multi-band, similar to the peak limiter. This clipper will add high-frequency noise to the transients, making them easier to hear.

Lastly, I didn’t enable any form of inter-sample peaking detection since it would lessen the impact of the transients – but I did enable 4x oversampling to help with inter-sample peaking and aliasing distortion.

Let’s listen as we enable each additional form of processing one by one.

Final Limiting – Limiter One

Last up, I added one more limiter to very subtly attenuate peaks and increase the overall loudness. Although this plugin doesn’t look like it would sound great, for some reason, Limiter One by CIS DSP factory has the best sound of any free limiter in my opinion.

Let’s listen to how this limiter pushes the master louder, and even improves the impact of transients.

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