ITB Mix Secrets: Part Two

The ITB Mix Secrets series of articles were written by Edvin A. of Function Loops exclusively for Razer Music.  Be sure to visit Function Loops for all your pro audio & loops needs.


In the first part of our ITB Mix Secrets series we have established that, besides setting up basic volume levels and panning, fixing time and phase issues per track can be a great starting point on a journey toward a great sounding mix. Once all that has been done, a recommended next step is basic filtering. Most raw sounds occupy an unnecessarily wide range of the overall frequency spectrum, thereby stealing precious headroom and presenting possible frequency buildup problems in the mix. So they should be filtered with both high and low-pass filters to focus on what’s important in the sound, and remove all that’s not needed.

In other words, (most) raw sounds naturally come with some extra content in both ends of the spectrum which is not required for the mix, so this additional content should be “filtered out” in order to free some “breathing space” and make a mix sound better.



IMG01: tuning the bottom-end with Bark of Dog

Tuning the Bottom-End

Using HPF (high-pass filters) and LPF (low-pass filters) to remove what’s not needed is nothing new, but what might be new to some is using a resonant HPF (instead of a classic one) which offers an impressive degree of control and a surprisingly musical way to “tune-in” the perfect bottom-end for your mix. Unlike a traditional filter, a resonant filter produces a resonant peak at the cutoff frequency that allows us to accentuate a specific “tone” in a sound.

To show what we mean, we will use a free plugin called Bark Of Dog, by Boz (IMG 01). (Alternatively, you can use a well-known Voice of God plugin, available for the UAD platform, or just a resonant high-pass filter in your DAW’s channel strip.

Bark of Dog is a simple tool, with several easy to understand controls. The knob in the middle is used for selecting the cutoff-frequency that, in this case, we use to determine the bottom-end “sweet spot” (basically a bass focal-point of the sound). The upper knob regulates the intensity of the (resonance) effect while the bottom knob is used for the wet/dry parallel processing, providing an even finer degree of tonal control. Everything bellow the cutoff point is removed while the cutoff frequency itself becomes a low-end focal point that we find/tune by ear, and then boost to the desired degree with the upper knob. It is a natural and musical way to dial-in a perfect-sounding bottom-end for all the sounds in your mix and clean away the unpleasant “mud”.

In the audio examples 1a and 1b, you can hear the difference between a raw and “bass-tuned” mix.


Tuning the Top-End 

In a similar fashion, one of the easiest and most efficient ways to manage the basic top-end of your sounds is by using a standard LPF (low-pass filter). Every decent DAW has it available as a part of its channel strip, but for this tutorial we have decided to use another excellent free tool; the Naive LPF plugin by Admiral Quality (IMG 02). This analog modelled filter offers both high and low pass filters with different slopes, plus a beautiful overall sound with some color and character. We will now use its default LPF setting and just remove all the unnecessary top-end content for all the tracks in our mix by tuning the cutoff frequency knob. Its default slope is quite steep, so if a softer effect is desired, just switch the “stages” bar on the left to change it.



IMG02: softening the highs with the LPF


By clearing up the unnecessary top-end, we open up some high-range breathing space and make more room in the mix.

In the audio examples 2a and 2b, you can hear the difference between a raw and “top-tuned” mix. 


Advanced filtering: Removing Resonant Build-ups

Once the basic filtering is done, we might notice that some of the sounds now exhibit unpleasant-sounding resonant buildups in the form of harshness. If that’s the case, we can address the problem with an EQ and manually cut the offending part of the spectrum, but even quicker and easier an approach is using a dedicated harshness controller plugin.



IMG03: removing harshness with bx_refinement’s dynamic mode


Currently there are several such tools available, both free and payware, with bx_refinement (by Plugin Alliance) and MannyM TripleD by Waves being the most popular payware solutions, while Terry West’s DeHarsh offers a nice free alternative. We will use bx_refinement to illustrate the point. This plugin can remove harshness statically or dynamically, with easy to dial parameters. We have found that removing harshness dynamically often gives better results because it is program dependant. In the examples 3a and 3b, you can hear the difference between the raw and harshness-tamed mix.



In some cases, unpleasant resonant buildups can span the spectrum and be difficult to pinpoint and remove with simple controllers and EQing, so using a dedicated un-filtering plugin is recommended. Currently, there are two such solutions available on the market: Zynaptiq’s excellent Unfilter, and Acon’s DeFilter. Unfilter is somewhat easier to get good results from because of its variable intensity control. These plugins analyze your sound and automatically remove undesired resonant buildups, resulting in a pleasant and a natural sounding curve.



By filtering out what’s not needed, we make more space for what we do want to hear. We “open-up” certain parts of the available spectrum so that they can be occupied by only the relevant sounds. Filtering can make a great difference, especially in busy mixes, and should be a standard part of your mixing routine.


This article was written by Edvin A. of Function Loops for Razer Music

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