High-pass filters frequently come up in music production and audio engineering work. Both equalization and sound design benefit from high-pass filters. But what are they and how do they work?
This post will deep dive into high-pass filters, discussing how they work, and their designs, and uses beyond just equalization.
What Is a High-Pass Filter?
High-pass filters are frequency filters that pass high frequencies from input sources while blocking low frequencies. These bandpass filters are an essential part of many audio applications and devices. They remove unwanted noise from signals and isolate certain frequencies for amplification, filtering, or other processes.
They are also high-cut filters because they cut out the lows and leave the highs. Simply put, high pass filters block out low frequencies while letting in the higher ones. Moreover, they are ubiquitous in today’s audio systems.
You may find high-performance filters (HPFs) on tangible devices, such as amplifiers, microphones, and speakers. In addition, you can’t imagine life without the digital high pass filter in your DAW. EQ plugins often include them, and some specialist compressors do as well. You may ruin a mix by overusing high pass filters, but if you know how to use them correctly, they are very useful for shaping sounds.
Types of High Pass Filters
We can divide high pass filters into two categories. These include:
Active and Passive
A passive high-pass filter has an “infinite” frequency response. In contrast, an active high-pass filter’s frequency response is limited by the open-loop attributes or bandwidth of the operational amplifier used.
Analog and Digital
Analog and digital high-pass filters remove low-frequency material from audio signals. Programming a digital high-pass filter may be easier because analog equipment has limited bandwidth and mixing options.
Your newly acquired knowledge of how and when to use a high-pass filter will enhance the quality of your mixes. The ability to harness the power of this basic instrument is crucial whether you’re working in a recording studio, a live performance setting, or fine-tuning a home stereo system. This article will explain high-pass filters, how they operate, and when they are useful.
What Is a High-Pass Filter Used For?
High-pass filters have numerous applications in almost any electronics project involving audio signals. They can:
Make Sounds More Distinct and Emphasize Lead Instruments
You should be able to hear the focal point of a musical composition above all other instruments. For instance, vocals must be at a higher volume than most other instruments and noises.
Using a high-pass filter may enhance the clarity and volume of a lead instrument or voice. It avoids the potentially unpleasant result of different sounds trying to occupy the same audio space.
Music producers often search for competing instrument frequencies to isolate the primary sound in a mix. For example, a high-pass filter, often with a cutoff frequency of 100 Hz or below, is used to mitigate the impact of these interfering frequencies.
It allows you to sculpt the sound frequencies in your mix more precisely and bring out the sounds you want others to hear.
Remove Undesirable Low Frequency
In audio, high -pass filters cut out low-frequency noise.
Whether you’re working with live recordings, effects, or samples, your music is almost certain to include unpleasant noises below the most apparent frequencies. Additionally, when dealing with analog high-pass filters, there will be a 90-degree phase shift for every integer increase in the filter order.
High-pass filters essentially remove frequencies below a certain threshold from the mix to eliminate undesired low-end sounds. In addition, it eliminates frequent undesirable noises like background noise, electrical buzzing, verbal interference, or static noise.
The final product is a fresh and lively blend.
Generate Motion With High-Pass Automation
Despite having all the necessary components, a track may nevertheless feel wrong even though it sounds excellent technically. It is often the case when the music in question isn’t very lively or responsive.
Automating the high-pass filter might give your song more energy and life.
Automation in music refers to the method used by the DAW (such as Logic Pro X, Ableton Live, or Pro Tools) to carry out ongoing, automated adjustments like turning knobs. In the case of high-pass automation, this might affect the cutoff frequency of sounds at different stages of the mix.
Enhance Bass and Kick Tones
When a lot is going on in the bass and kick areas of the mix, it’s hard for those sounds to stand out. You will likely have subpar results if the kicks don’t stand out from the rest of the music.
The music will sound flat and uninteresting if the listeners can’t hear the kick beats clearly because of a lack of low end. The same holds for low end instruments. Your music won’t have the desired rhythm and motion if other low-end noises drown out the bass lines.
The good news is that the bottom end becomes tighter and more distinct when bass and kick sounds pass through a filter with a high-pass frequency (20-60 Hz).
However, don’t remove too much bass and risk the song sounding thin. Remember, mixing and mastering are all about striking a balance, and doing this may make the mids and highs seem too prominent and remove thickness from the mix.
Utilize High-Pass Filters With Dynamic Equalization
Dynamic equalization adjusts the cutoff frequencies and EQ curves in real time to match the incoming audio input and consider the inherent frequency shifts in the recording.
Low-end frequencies are easier to manage using dynamic high-pass filters since they adapt to the varying levels of bass throughout the composition. For example, if a standard high-pass filter clears up the sound of your instrument in one part of the song but not the next, you may want to try a dynamic EQ filter instead.
What Is the Cutoff Frequency of a High-Pass Filter?
One way to describe a high-pass filter’s cutoff frequency is as the frequency at which its output begins to reduce significantly. Attenuation is a weakening of a signal in any way. No signal, digital or analog, is immune to attenuation.
In response to an input signal, a high-pass filter outputs only those signals at higher frequencies than a certain threshold frequency. For example, a high-pass filter allows all frequencies above some threshold frequency and rejects all frequencies below that threshold.
High-frequency signals have frequencies above the cutoff frequency, while low-frequency signals have frequencies below the cutoff frequency.
A cutoff frequency is a point at which the highest peak falls to half its original value. The highest peak determines the peak response or peak gain, with the lower cut reducing any remaining energy after passing through a bandpass filter.
Since most high-pass filters have endlessly adjustable cutoff frequencies, an engineer may use a knob to fix the cutoff frequency more accurately. However, you can only switch between a limited number of frequencies if the high-pass filters do not have infinitely adjustable cutoff frequencies.
What Is the Difference Between a High-Pass and Low-Pass Filter?
The high-pass filter and low pass filter are two different filters that have the same general aim: to allow certain frequencies of sound through while blocking others. They are opposites because high pass lets high frequencies or high-pitched sounds through while low pass allows lower frequencies (such as the lows and lows) through.
High-pass and low-pass filters are part of bandpass filters that let only certain ranges of frequencies through. High-pass and low-pass filters are second order band pass filters, which lets the highest or lowest range of frequencies through.
Distinctive Features of High-Pass and Low-Pass Filters
- The basic difference between high-pass and low-pass filters is that the former passes signals with frequencies higher than the cut off frequency, while the latter passes signals with frequencies lower than the cut off frequency.
- High-pass and low pass filter circuits have different designs; the high-pass filter comprises a capacitor followed by a parallel pair of resistors. A resistor follows the capacitor in a low pass filter circuit.
- High-pass filters are used in audio amplifiers to couple or eliminate distortions brought on by low-frequency signals like noise. In contrast, the low-pass filter acts as an anti-aliasing filter.
What Is a Good High-Pass Filter Setting?
Do you want higher audio quality? With the help of a high-pass filter, even inexpensive speakers may sound and perform far better than they otherwise would.
The specifications provided by manufacturers often contain information on the recommended cutoff frequency. However, we have curated the information for you if it’s not specified.
High-Pass Crossover Frequency for Home Audio
- You must set small tower-type front speakers and large tower-type front speakers at 60-80 Hz high-pass filter crossover frequency.
- You must set a small surround or center sound system at 100-120Hz high-pass filter crossover frequency.
- The desirable frequency range for medium or large surround sound (center/surround) is a 60-80Hz high-pass filter.
- Wall-mounted or small satellite speakers should be set at 100-120Hz high-pass frequency spectrum.
- You must set the 2-way speaker systems frequency at 3kHz to 3.5KHz
- 3-way speaker systems must be set at 3.5kHz high pass for the tweeter and 250-500Hz high pass for mid range speakers.
- Subwoofer subsonic filter should be set at 20-30Hz high-pass filter frequency.
High-Pass Crossover Frequency for Car Audio
- You must set frequency response for front or rear full-range coaxial or component speakers at 56, 60, to 80 Hz
- You can set the frequency range for tweeters’ in-car audio at the 3-3.5kHz high pass.
- Woofer or midrange speakers perform best if you set them at 250-500Hz high-pass filter crossover frequency.
- The most desirable high-pass frequency range for 2-way speaker systems is 3kHz to 3.5KHz to tweeters.
- 3-way speaker setups should be set at 3.5kHz (mid/treble) & 500Hz (mid/woofer) to get the best results.
- A frequency set at 20-30Hz high pass of a subwoofer subsonic filter will yield the best results.
Final Words
A high-pass filter plays a significant part in ensuring the highest possible sound quality by allowing some sounds whose frequencies are higher than the cutoff frequencies while reducing the volume of signals with lower frequencies. The cutoff frequency’s design determines the value of the filter.
So, get a high-pass filter if you want the highest sound quality.
