High Pass Filter and Low Pass Filter – The Difference Explained

The high pass filter and low pass filter get confused with one another as the names can be misleading. It’s important to understand the difference as I talk about them a lot regarding my EQ guides, and they can literally save your mix. Let’s cover the difference between the high pass filter and low pass filter and when and how to use each.

High Pass Filter and Low Pass Filter

As we cover the differences between the high pass filter and low pass filter, let’s look at each one individually.

High Pass Filter

A high pass filter sounds like it targets higher frequencies, but really it’s the lower frequencies which get filtered out with a high pass filter.

The term “high pass filter” refers to the higher frequencies being the ones which pass through, untouched by the filter.

For instance, setting a high pass filter at 1000Hz will filter out everything BELOW 1000Hz, whereas everything above 1000Hz will remain audible:

A high pass filter is one of the most important EQ moves you can make on virtually every track.

Most tracks in your mix don’t have any musical or wanted frequencies below 100Hz whether it’s from ambient noise outside (see the difference between high frequencies and low frequencies) or inside.

Even if you have musical frequencies at that point, you generally want to save that space for your kick and bass specifically. This is one of the fundamentals of low end mixing.

This also cleans up the mud from your mix and creates headroom by removing inaudible frequencies which we can’t hear but over the course of dozens of tracks can add volume.

As the image shows above, 100Hz is generally a good place to create a high pass filter on 95% of the tracks in your mix.

I go into more detail in my overview on the high pass filter and specifically in my complete and free EQ cheat sheet, showing the best place to high pass filter in every track in your mix and additional settings like the slope and Q to use.

Low Pass Filter

Not surprisingly, the low pass filter operates in exactly the opposite way as the high pass filter.

In other words, the low pass filter leaves the lower frequencies intact while removing everything ABOVE the frequency point you set.

Setting the low pass filter at 1000Hz filters out everything above 1000Hz while the lower frequencies are passed through to remain audible.

As the image above shows, low pass filters are useful in a number of situations.

Whereas we can’t hear below 20Hz, we also can’t hear above 20,000Hz. Similar to how frequencies in the low end can pile up on top of one another, they can do the same on the top end. While this doesn’t cause the mud that the low end can, this can still take away from the headroom of our mix.

As I also offered in my low end mixing tutorial, we can drop a low pass filter on a reference track to get a good idea of how a professional mix treats its low end.

Drop a low pass filter at 150Hz on your reference with a decent slope of 24dB/oct to almost exclusively hear the bass and kick. This shows you how they’re balanced with one another which you can apply to your own mix.

This also will demonstrate just how much of the rest of their mix is high pass filtered out like I mentioned earlier.

You may be surprised when you hear virtually nothing but bass and kick, even as high as 150Hz. That’s a lot of the reason that commercials mixes sound so clean and focused, and your mix can benefit from the same moves.

So, in summary on high pass filters and low pass filters, you should use both extensively throughout your mix, featuring one of each on virtually every single track in your mix.

Just make sure you have my EQ cheat sheet to know exactly where to place each on each individual track in your mix.