When it comes to mixing, your first thought might be of using EQ, reverb and perhaps compression as the staple, go-to processors to shape each channel. These are indeed a core element of working with any track in any mix, but it's also important to understand the value that filters can bring to your productions. Much more than DJ or synth-style effects, they are very useful mix tools as well. In this short video from the course AudioPedia 108: Mixing and Mastering, Joe Albano explains why.
Low Pass, High Pass and Band Pass filters all filter out different parts of the frequency spectrum and can be used not only for telephone line-type effects but for much more common tasks like rolling off hum and rumble at the bottom end of a track, or extreme hiss at the other. As ever, the key is to use them subtly and with precision, being careful not to accidentally dull down frequencies you actually want to keep. Joe shows you how to combine filters for more surgical results, and demonstrates concepts including notch filtering which can be used for very precise targeting of frequencies.
Check out the full course using the links below for a quick and concise guide to everything you need to know about mixing and mastering.