High pass filters are a great tool to reach for in a mix if you find that low end energy is causing a track to sound a bit thick, muddy or boomy. A full mix can sound muddy or unfocused if individual tracks have not had some degree of high pass filtering applied. Excessive low frequencies can upset a track’s intelligibility, especially on vocal or spoken word tracks. Using a high pass filter in these types of scenarios can go a long way towards focusing the wanted sound and losing the unwanted elements.
High Pass Or Low Cut?
A high-pass filter simply attenuates below a set frequency point and lets higher frequencies pass through, hence the name “high pass” filter, though many people refer to these filters as low cut, the key here is that low-cut and high -pass are two ways of describing the same thing.
Why Use High Pass Filters?
High pass filters are very useful tools to remove unwanted low frequency sounds without affecting the wanted sounds. In the case when a number of performers are recorded in the same space on mics picking up sounds that don’t have much low frequency content, you can use high pass filters to remove unwanted low frequency spill from other instruments being picked up on different mics in the room. Increase the cut-off point of the filter until it is just starting to affect the wanted sound and then back it off just a little.
When it comes to speech and VO work, using a high pass filter on speech or vocals can improve the clarity and intelligibility of the voice, especially when close miced as many mics artificially boost the low frequencies and this can mean the voice ends up being boomy.
It can be very easy to overdo the use of high-pass filters and lose too much body from a track’s tone. Practise makes perfect, the more you use high pass filters the better you’ll become at setting them without even thinking about it.
Where To Find High Pass Filters
All major DAW’s have a dedicated filter plug-in of some description as part of the stock plug-ins. There are countless fully featured EQ’s that also feature filters such as FabFilter Pro-Q3 which we used in the production of this video.
The other main control in high pass filters, apart from the cut-off frequency, is the slope control. which depending on the plug-in can be set in variety of values. Slopes are typically quantified in decibels per octave.
If you are new to mixing then make mastering low and high pass filters a priority as these are essential tools for producing focused sounding mixes that you will be proud of.