This One Knob Could Change Your Life

Meet the unsung hero of audio mixing— The High Pass Filter.

This one knob could change your life. Well, the mixing life on your console.

The High Pass Filter (HPF) will not fix your relationships and finances or get you a promotion at work – but it CAN make mixing much easier.

What does the High Pass Filter do?

It helps remove a lot of rumble and unwanted low-end in your mix. Removing these unwanted low frequencies gets you a lot of clarity and intelligibility out of all your inputs in a hurry.

Some consoles call this a "low cut filter", such as the X32 and M32 series consoles. It's called a low-cut filter because it is easier for newcomers to understand that the low frequencies are being cut. High Pass Filter means everything higher than a specific frequency will pass, meaning things lower than a set frequency will not pass. 

It's the same tool, just with two different names. 

Simply put, The High Pass Filter eliminates unwanted rumble and noise. Overall, it gets you a lot of bang for your buck – If your buck is seconds while you're trying to get your mix together.

I mean, time is money. 

Here are three powerful things the High Pass Filter can do in your mix.

1. Remove unwanted Pops and Rumble from your mix.

The High Pass Filter is an essential tool that helps remove unwanted pops and rumble your mix. It can be quite distracting when someone speaks into a handheld microphone and there is a sudden "pop" sound from their plosives. These sounds can negatively affect sound clarity, making people question the sound technician's abilities.

We don't want people thinking about us. We want people to think about what's happening on stage.

So, what are "Plosives"? Plosives are sounds associated with the letters p, t, k, b, d, and g. If you grab a microphone and say something like "Please Pray for Peace," you will notice how the "P" sounds can sound "boomy". If you roll up your High Pass Filter, it can help clear that up. 

I prefer setting the HPF between 150 and 200 for female voices, and between 200 and 250 for male voices. I find success around these areas - but always remember to use your ears when mixing.

Sometimes, a male has a higher-pitched voice. Other times, a female's voice could be lower. Rolling the HPF too high can result in a voice sounding too thin, losing some of the "heart" of a voice. Remember to adjust the High Pass Filter as necessary. These settings serve as good starting points but do not apply to every singer or speaker.

2. Eliminate Unwanted Noise going into the microphone.

The second thing the High Pass Filter does is eliminate unwanted noise from other inputs in the microphone.

It's tough to reject low frequencies in microphones. Even the backside of the microphone, the part that's supposed to reject the most sound, still picks up a good amount of low frequencies. With our High Pass Filter, we can turn all of those down. Then we can have a cleaner signal being sent to our console.

3. Increase Intelligibility due to Masking.

A third thing that the High Pass Filter does is increase intelligibility due to a phenomenon called Masking. Masking says loud sounds will cover up quiet sounds, which is pretty obvious. But the less obvious version is that low frequencies will cover up high frequencies. Even if all the intelligibility frequencies in the upper midrange are present in your microphone, if there are too many muffled sounds coming to that microphone, we won't be able to perceive those upper middle frequencies. We want our vocal and speaker microphones to sound as clear as possible, so turn up the HPF if your mic is sounding muffled or covered. 

Want to see some examples of me using the High Pass Filter? Here's a link to a video I created showing how to use it in real time. I skip to where I apply the HPF to various sound inputs. (You can also watch it in this blog post.)

Watching the video above lets you see how various sound inputs get clearer using the High Pass Filter. The HPF is a versatile tool that is handy in cutting lows in a pinch or reducing rumble in microphones and can also be applied to many different instruments.

It's a simple yet powerful tool.

What makes a Great Mix?

In the grand scheme of a great mix, there are four components you need to start. The first thing to consider is ensuring that the right microphone is being used for the right source. Secondly, it's important to place the microphone in the correct position. Thirdly, you need to balance all of the different inputs and manage the gain structure. This involves turning up the preamp and fader at the right place and time to ensure that your mix is balanced and your equipment is operating at its best.

The High Pass Filter is the fourth part of this equation. Things get cleaned up quickly when unwanted noise is reduced, and the HPF is essential in cutting those pesky low frequencies.

Key Takeaways:

1. The High Pass Filter (HPF) is a powerful tool that removes unwanted low frequencies from your mix, resulting in greater clarity and intelligibility.

2. The HPF can be used to eliminate pops and rumble caused by plosive sounds in vocals and unwanted noise from other sound inputs.

3. The HPF can also increase intelligibility by reducing masking, which occurs when low frequencies cover up high frequencies.

4. To use the HPF effectively, start by choosing the right mic and placement, balancing your inputs and setting the gain structure correctly, and then applying the HPF to clean up unwanted rumble.

5. Use your ears when setting the HPF frequency, as the optimal setting may vary depending on the source. No voice is the same.

Need A Live Mixing Field Guide?

If you want some tips and tricks on how I set up each EQ and compression for different instruments that you're likely to find at church, I've got all that in a handy book called The Live Mixing Field Guide, and it comes with a companion course on the basics of EQ and compression.

If you're new or just getting started with sound and want to get familiar with some good starting places for your EQ, you can purchase the Live Mixing Field Guide at www.livemixingfieldguide.com. (You could also click the image above!)

Ready to dive into more about Church Sound?

If you want to learn more about running sound in church or just about sound in general, check out Attaway Audio Academy. There's tons of course content for sound technicians and worship leaders, weekly live Q&As, and an incredible community. Whether you're brand new to sound or a seasoned tech - there's something for everyone. The price has been knocked down to $19 a month as well!

I pray blessings to you as you diligently serve the Lord and I pray for growth in your knowledge of sound. Remember - it's all about the low end, avoid the sound tech solo, and nobody leaves church humming the kick drum.

Stay safe out there, Sound Ninjas!
James

Check out this video to learn more about The High Pass Filter!