An audio pass filter reduces the frequency range of an audio signal. It is an amplifier circuit that is dependent on frequency and also operates in a range of audio frequencies from 0 to 20 kHz. Some frequency ranges can be boosted (boosted), passed (passed), or cut (cut) using audio filters. For various audio applications, such as musical synthesizers, hi-fi stereo systems, sound reinforcement systems, sound effects, virtual reality systems, and instrument amplifiers, a variety of filters are available.

What is a high pass filter?

HPF or a high-pass filter allows signals with frequencies higher than a particular cut-off frequency to pass while reducing signals with lower than the cutoff frequency. The filter design determines the amount of reduction for each frequency. In the world of audio engineering, it’s known as a low-cut filter or a bass-cut filter.

A high-pass filter essentially cuts out a mic’s frequency response below a certain fixed point, allowing only frequencies above that point to “pass” through as the audio signal. High-pass filters eliminate unnecessary and unused low-end energy from the audio signal, which would otherwise weaken it.

High-pass filtering all channels or microphones that aren’t directly reproducing sounds of lower frequency sources is popular advice.

Why do you need to use a high pass filter?

• To exclude rumble and noise from the signal’s low end

HPFs are sometimes used to remove rumbles of low-end and noise from microphone signals. 

There aren’t many sound sources that produce useful sound at frequencies below 50 Hz. Ambient noise and rumble make up the majority of low-frequency sound energy. The following are some common sources of low-frequency noise:

• The power lines buzz (50-60 Hz)
• Air conditioners produce quite a lot of noise

These external sources of low-end noises will eventually get to the microphone even in soundproof audio booths. We get a clearer signal with more headroom after high-passing and eliminating noises of low-end. 

• To Reduce the Effect of Proximity

The proximity effect is observed with directional microphones. Microphones with a bi-directional “figure-8” polar pattern have the greatest proximity effect.

The proximity effect can be used to our benefit on occasion. However, it is often a drawback with directional microphones.

• To Reduce Plosives

The “b-pops” or “p-pops” that we hear in the microphone are plosives. Gusts of air produce a huge change of pressure at the diaphragm of the microphone, which causes them. People’s mouths sometimes create these air gusts when they talk or sing words beginning with the letters ‘P’ or ‘B.’

Since plosives have a lot of low-end detail, the high-pass filters may help reduce the strength of the sound. It’s worth noting that HPFs aren’t a good way to deal with the source of plosives. They’re nothing more than a band-aid for the symptoms. Also, when using a high-pass filter, a lot of the plosive energy can be clearly heard in the signal. This isn’t a healthy situation.

• To Mix Audio

High-pass filters work best when used in conjunction with an audio mix. It doesn’t matter even if musical information in the low-end is included in the signal of the microphone, it may be beneficial to remove these frequencies of low-end to free up space for other instruments.

What is a low pass filter?

A low-pass filter (LPF) is a filter that  allows signals with lower frequencies to pass while attenuating signals with higher frequencies. The frequency response is determined by its nature. In audio applications, the filter is known as a high-cut filter or treble-cut filter. The counterpart of a high-pass filter is a low-pass filter.

Why should you use a low pass filter?

• To boost the bass

As high frequencies are reduced, lower frequencies become more dominant. Remember that a low-pass filter allows low frequencies to pass through more easily.

You may use an LPF on an instrument that requires a lower end.

• To tame high frequencies

You may also use an LPF to bring in a hi-hat or even a vocal that has harsh high frequencies.

In this case, you don’t want to cut all those high frequencies because it will reduce the instrument’s sound. Cutting only the super high frequencies, on the other hand, will help.

• To create depth

The listener interprets your sound as having a front and back when you use depth in your mix. Some instruments will have a more distant sound, while others will have a more forward sound.

The benefit knobs and even panning are used to accomplish this. Using an LPF, on the other hand, will make an instrument sound less present.

You can add dimension to your mix by moving elements to the back of the mix with an LPF.

So which one should you get?

Low and high pass filters each serve a distinct purpose. It’s all about influencing the energy above or below the target frequency. This is commonly referred to as the cutoff frequency in pass filters by sound engineers.

By adjusting gain, low and high pass filters do not cut or improve frequency material. Instead, they delete the objectionable material from the audio so that it is no longer audible.

In a nutshell, low pass filters give us a lot of control over our mixes in terms of creativity and correction. As a result, they are used to enhance harmony and consistency in all types of music. On the other hand, high pass filters are an extremely versatile tool that can be used in a variety of situations to improve tonal balance. So it is up to you to understand what kind of sound you want to go for, and decide based on that.

While there is no clear answer to the question of which one is better in high pass vs. low pass filters, we sure hope we were able to help answer some of your queries.