If you’ve been mixing for any length of time, you know how valuable the high-pass filter can be. It removes excess low end from your non-bass-heavy tracks, allowing you to clean up the low frequencies, making room for the kick and bass.

But then there’s this thing called a low frequency shelf. What’s that all about? In the picture above you can see both a high-pass filter and a low frequency shelf.

A high-pass filter actually filters out the low frequencies entirely. The curve slopes downward at a specific “steepness.” As you move further to the left in the frequency spectrum, the signal gets progressively lower and lower.

If you set the HPF at 150 Hz, for example, 120 Hz will still be audible, but will be turned down. 80 Hz will be much quieter than 120. 40 Hz will likely be completely unheard. The high-pass filter essentially REMOVES those lower frequencies.

But let’s say you don’t want to completely remove the low frequencies, but you’d like them to be turned down a bit. That’s where a low shelf can come in handy.

If you look at the graphic again, a low shelf looks just like it sounds. It’s a horizontal line. Any boost or cut applied to the shelf also applies evenly to every frequency below it. This can be extremely helpful on a bass track that has just a little too much low end. You can turn everything below 150 Hz down by 3 dB. You’re not getting rid of the good stuff down at 80 Hz, you’re just turning it down.

Where I use this a lot is on a bass track, where I use a regular EQ curve to cut out some of the muddyness around 120 Hz, but then I’ll also use a low shelf to turn the bass frequencies down a bit…if needed. This lets me shape the tone of the low end with the bell-curve, and then increase or decrease the loudness of the low end with the shelf. Here’s what that looks like:

As you might have guessed, the same can be applied on the other end of the spectrum, when dealing with the high frequencies. I tend to use this on the lows more than the highs, though.

What do you think? Do you ever use a low shelf? Leave a comment below. Thanks!

Also, if you want in-depth EQ training, click here.

  • Jay Alvarez

    This was great , I never use a shelf for bass, usually a high pass filter only.This makes sense I got to try to self very soon thank you

  • Danilo Dara

    Very nice a description, thanks.
    Still, there is something I don’t get.
    Since the gain can be positive ( boost ), or negative ( reduction ), there seems to be no need for a High Shelf.
    While, actually, High Shelves exist.
    So, why differentiating something which could apparently be a single tool?

  • Zardak Edwards

    You are the first one to actually explain in plain accurate simple language exactly what these are and what they do. I have been in the dark about this EQ type for several years. God bless you and thankyou! Seems many music-production forum members are precious about such knowledge and don’t want to empower others to end-up being potential rivals in the audio-world.

  • Reverend Aquaman

    Thanks for the info. Exactly what I needed to know and the sound is much better. Cheers.

  • CameronN

     Studio One EQ!!

  • Glenn

    This was the only useful explanation of the difference between HPF and LS that I found on the web…..well done….

  • Bassplaya4string

    Awesome tips! Thanks Joe!

  • Gayzee

    Hey Joe,
    Good article, thanks.

    Looking at your screen shots, are you using Presonus Studio One now? If so, how do you find the eq and compression?

  • Astewart

    Interesting post Joe… would you recommend doing it with one plug in, or do the hp filter on one plug in, then following up with the low shelf?  I am thinking it would be different that way…