How to use warm filters in the winter studio

By | April 4, 2021


High- and low-pass filters are undoubtedly one of the best tools for cleaning up and creating space among your instruments when mixing. A basic understanding of these filters and how to use them is in my opinion extremely important to get a good end result.

The picture shows a standard high-pass filter, also called a low-cut or high-pass

Two schools
There are actually two clear schools when it comes to the use of filters. On the one hand, those who believe that, above all, high-pass filters should be used on all channels. And those who claim that filters should only be used on the channels where they really do benefit. It is important to understand in this context, however, that both schools really want the same thing: namely to create space at the bottom and the top, without the mix losing its warmth and clarity.

A warm and cuddly mix
Today’s Friday tips do not advocate one or the other approach, but instead focus on the purpose itself: A warm, cuddly and separated mix with retained clarity and air.

The problem with using filters in general is that if we cut off too much with high-pass filters, it sounds cold and sterile. Or too dull and lifeless with a low-pass filter. We then try to remedy this by compensating with a lot of analog plugs in the hope of heat. Or even worse, we boost wild game frequencies that we really have no control over. In other words, you solve a problem, but in the next step you create a new one.

Now I am not saying that you should stop using analog plugs, they are wonderful if used properly. I just mean that you should not start by creating problems when you mix, which then have to be solved. There are easily many plugs in the signal chain, so to speak. So what is my suggestion?

Filter in a new-old way
It’s all pretty simple: Boost at the same frequency as you cut off, both for high and low pass filters. But only on the channels where it is really needed. The channels that carry the mix. Exactly which instruments are in other words difficult to say and differ from time to time. Let’s say bass, bass, vortex, guitars and vocals, for the sake of simplicity.

The picture shows a base channel with as well as high- and low-pass filters with -24 dB slope and a peak on the unrolled frequencies.

This phenomenon is also called resonant peak and is common in the analog world, although it occurs naturally due to the shortcomings in electronics. What happens is simply that you amplify the frequencies that have been cut off, which in practice means that you get rid of rumbling, or hissing sounds if you use low-pass, but at the same time highlight what you actually want to hear. This both leaves room in the mix and provides a more focused sound, with less intrusive midrange. How much to boost can (as usual) not be said, but at least 2-3 dB for it to give an audible result.

Well, a sound sample says more than a thousand words. On with the headphones!

  1. Base: Standard high- and low-pass filter
  2. Base: Resonance stop files

At first glance, the difference may seem a little subtle. But focus on the bottom, how it thickens in a wonderful way, and the top where the string sound and the attack come out. At the same time, the confinement disappears. Then imagine that you work similarly with other important instruments and vips so the sum of the cardamom is something really good and sounding. Every little helps…

And so it was with that thing.

Feel free to ask questions or comment on the article in the comment field below, and we will spin the topic together. Or if you prefer to discuss mixing in the “Mixing and mastering” section of the Studios forum here!

Fredagstipset is a recurring series where Studio writer Jon Rinneby shares tips every Friday in, among other things, recording and mixing. Here you will find all Friday tips.