The Mighty High Pass Filter: Are You Well Acquainted With This Essential Mixing Tool?

You can get a good idea of how steep it is by sweeping the control up and seeing how quickly the low end falls off (assuming you have a threshold control).

In practical use, I approach HPFs this way; if I’m dealing with a simple switch (that is, no threshold control) I turn them on for every channel on the board except for the kick, floor tom, bass and electronic keyboards.

Generally speaking, there’s not much musical content below 75-100 Hz for vocals, acoustic guitar or much anything else, and what is there typically muddies up the sound.

Engaging the HPF in this way helps eliminate a lot of low end rumble as well as low frequency feedback in the monitors.

If I have a threshold control, I’ll turn it on for every channel and adjust the individual controls as needed. For a kick, I might have the HPF set to 30-50 Hz, just to clean up the extreme low end.

On vocals, I normally start at 120, but sometimes run up as high as 150-180 depending on the voice, the mic and what I’m hearing.

If plosives are a problem, turning the HPF up can take some of them out. It can also make the speaker sound very thin and tinny, so be careful.

For other instruments like acoustic guitar, I like an HPF at 150 or so to tame some of the body resonances. Again, you have to be careful, but this is a good place to start (always listen…).

You can also use high pass filters on things like cymbals. I have my HPF on the high hat channel turned way up around 500 Hz or so.

That cuts out some of the bleed from the toms and snare, cleaning up the high hat sound. If you want your overheads to act as cymbal mics, do the same thing. On the other hand, if you want to pick up the toms and snare, but not the kick, you can set it around 120 or so.

Like every other control on a sound mixer, you have to listen, not just follow numbers.

The best way to learn what the HPF sounds like on your board is put on some headphones, solo up the channel and either turn it on or off, or turn it on and sweep the threshold up and down. When you arrive at something that sounds pleasing, stop.

Are you well acquainted with your HPF or are you just learning the ropes? Let me know in the comments below!

Mike Sessler is the Technical Director at Coast Hills Community Church in Aliso Viejo, CA. He has been involved in live production for over 20 years and is the author of the blog, Church Tech Arts . He also hosts a weekly podcast called Church Tech Weekly on the TechArtsNetwork.