A lot is made of ‘clearing up the bottom end’ with high pass filters. You have to be careful – with electronic sources you can do a lot of this sort of thing, but with live instruments you make them un-natural quickly. It’s important to be aware of the way a high-pass filter affects the phase of the source, and so how that disrupts relationships in multiple-mic’d sources like a drum kit. So, horses for courses, but consider how aggressive you want to be with this depending on the nature of your production.
On a related note – Low-pass filtering – A modern digital system is capable of capturing frequencies that the brain naturally filters in ‘real life’ – accordingly things can sound a bit uncomfortable, and sometimes thin or brittle, in a way that they did not with tape/vinyl. Work the low pass in the same way as the high pass. If you need a source to be really bright (and you probably do) try controlling the top end at the same time as boosting it.
Jack Ruston is an in-demand producer, recording engineer, mixer and all round audio geek.