If I would have to name the one thing that made the biggest impact on my mixes it would be making sure my sound sources are great before even mixing. That is kind of a no-brainer though.
The second biggest thing is what I want to talk about today: Using filters on every channel of my mix.
Using high-pass and low-pass filters is the simplest technique you can ever learn but is also very often overlooked by not yet professional mixers. The workings of these filters are simple. They have general speaking only two settings: a cutoff frequency and a slope (often referred to as Q).
For a high-pass filter the cutoff frequency would mean that every frequency above the cutoff number is unprocessed and ever frequency under it gets filtered (deleted). The slope determines how steep the frequencies close to the cutoff frequency get cut off.
That’s the easy part. Now why you should you want to filter all the elements of your mix?
A mix is like a shoebox; you can only fit a maximum amount of instruments in the shoebox. By filtering out certain frequencies areas of instruments that don’t need those frequencies you create extra room in that box. Room you desperately need to fit all your sounds together in that space, while still being able to see / hear everything.
Example: a snare drum might not need any frequencies under 50Hz, but my 808 kick drum does. Why would I waste space (small as it may be) on the 50Hz portion of my snare drum that could also be used to give my 808 kick extra breathing room? Imagine doing this for all your drum elements and your 808 kick will sound bigger than ever.
Erasing phantom frequencies
You are mixing for people to listen to your songs. Because of that you need to take into consideration the playback medium they are using to listen to those songs. A lot of speakers (especially laptop and smartphone speakers) and earbuds cannot display a wide range of frequencies. Especially in the lower areas they are really struggling with this. If you have a lot of really low frequencies in your mix it might distort the speakers or muddy up the playback of your mix.
That is why I like to put a high-pass filter on all my channels while mixing. On top of that by getting rid of low frequency rumble the high frequencies become more sparkling.
If you are mixing in the box these plug-ins will take up processing resources. Should your computer not be able to handle that many plug-ins, a trick you can use is creating sub-busses. What that means is creating a stereo bus / aux track and route all your individual channels to those busses (for example all your drum channels to a drum buss). This way you can just put a filter on the specific buss and have all the channels filtered by only using 1 filter. I prefer the sound of filtering everything individually though.
Creating a special tone
Another added benefit of using filters is that each filter has a distinct sound. Although with digital filters that sound can be not noticeable, depending on the manufacturer and intention of their creation. This way you can add all kind of small and subtle colors to your mix in an easy way. A personal favorite of mine for this is the Sonimus Satson, which has a fat option I really like.
If you are not using filters you are missing out on the easiest technique to make a big impact on your mixes. It’s quick, easy and fun to experiment with.
Read More: Quick Tip 12 – Boosting Drum Transients