High Pass Filter (HPF) and Low Pass Filter (LPF) Mega Thread

[jb90]

I don't know why manufacturers don't make amps or effects with build in HPF/LPF settings? It's probably not a thing in guitars (most speakers handle 100hz and above very good) but for bass? Those frequencies consume a lot of power and most of the time are unhearable anyway. Not mention high freq response. Most of 4 strings end at about 5kHz. Even ERB-s with high F string can handle maybe 12k at most (with all noticeable harmonics!). So why even consider to have higher frequencies like that in your sound and add unpleasant hiss and piercing treble from tweeter? Which IMO should be rather kind of mid-high speaker instead of this small treble thing. I make tests of my cab (Handbox 2x12 w tweeter) and from 20-25hz are very bad distortions. 30-35hz? The true tone of the bass (not only air pufff) appear. 40-50hz - I can hear good, define tones not just some "farts". But other thing is why cab manufacturers don't make better speakers? Many studio monitors are smaller and have smaller drivers but can handle even 40-50hz flat. Most bass cabs can handle maybe 50-60hz and at least +/-3db (so probably about 100hz there's a "flat"). Bigger cabs, bigger drivers, worse freq response of low end. Why is that? It's a matter of power or just bass cab manufacturers don't care? Cause I think I realized why many today bass players and musicians rely only on in-ears and one of the reason could be the "bad quality" of amplification.

 

[agedhorse]

I don't know why manufacturers don't make amps or effects with build in HPF/LPF settings? It's probably not a thing in guitars (most speakers handle 100hz and above very good) but for bass? Those frequencies consume a lot of power and most of the time are unhearable anyway. Not mention high freq response. Most of 4 strings end at about 5kHz. Even ERB-s with high F string can handle maybe 12k at most (with all noticeable harmonics!). So why even consider to have higher frequencies like that in your sound and add unpleasant hiss and piercing treble from tweeter? Which IMO should be rather kind of mid-high speaker instead of this small treble thing. I make tests of my cab (Handbox 2x12 w tweeter) and from 20-25hz are very bad distortions. 30-35hz? The true tone of the bass (not only air pufff) appear. 40-50hz - I can hear good, define tones not just some "farts". But other thing is why cab manufacturers don't make better speakers? Many studio monitors are smaller and have smaller drivers but can handle even 40-50hz flat. Most bass cabs can handle maybe 50-60hz and at least +/-3db (so probably about 100hz there's a "flat"). Bigger cabs, bigger drivers, worse freq response of low end. Why is that? It's a matter of power or just bass cab manufacturers don't care? Cause I think I realized why many today bass players and musicians rely only on in-ears and one of the reason could be the "bad quality" of amplification.

Most better amps do have HPF’s, some are adjustable too.

The smaller studio monitors can’t get anywhere near loud enough at low frequencies for live bass guitar applications.

It’s different products for different applications.

 

[lowplaces]

Will a LPF dial out pick noise ? (Playing with a pick)

 

[agedhorse]

Will a LPF dial out pick noise ? (Playing with a pick)

They can, it depends on the tone you are looking for.

 

[Akiyama]

HPFs/LPFs have their place but there is much to be said for the experience of non-periodic and periodic sub and infra-frequencies as well as ultra-frequencies. Some experiences being quite positive. Some exposure to these frequencies are necessary for proper neural development. Now, this frequency range can also be harmful under some conditions. Usually not from an instrument, though.

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Electric and acoustic instruments usually have atonal or extraneous elements that give music “life”. As I am primarily an electronic musician, where those extraneous elements are much less present/available than in electric and/or acoustic instruments, this can lead to feeling a piece is “stiff” or lacking “soul”. If you totally eliminate those sounds via filtering, well, you might be better off playing a synth/sampler.

 

[agedhorse]

HPFs/LPFs have their place but there is much to be said for the experience of non-periodic and periodic sub and infra-frequencies as well as ultra-frequencies. Some experiences being quite positive. Some exposure to these frequencies are necessary for proper neural development. Now, this frequency range can also be harmful under some conditions. Usually not from an instrument, though.

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Electric and acoustic instruments usually have atonal or extraneous elements that give music “life”. As I am primarily an electronic musician, where those extraneous elements are much less present/available than in electric and/or acoustic instruments, this can lead to feeling a piece is “stiff” or lacking “soul”. If you totally eliminate those sounds via filtering, well, you might be better off playing a synth/sampler.

Actually, when a player chooses their preference with a HPF because is sounds clearer and more articulate, that’s all that matters.

Since bass amps can’t come close to reproducing sub and infrasonic signal components with any kind of accuracy, it’s kind of a moot point anyway.

 

[Akiyama]

Actually, when a player chooses their preference with a HPF because is sounds clearer and more articulate, that’s all that matters.

Since bass amps can’t come close to reproducing sub and infrasonic signal components with any kind of accuracy, it’s kind of a moot point anyway.

From an acoustic engineering standpoint, that is a strong argument with great merit. From a psychoacoustic perspective, there can arise issues with "over filtering".

To save myself time I will submit some AI responses that are consistent with my academic understandings of and personal experience as a musician on the topic.
__________________________________________________
From a psychoacoustic perspective, a bass guitar amp should not filter frequencies below 40 Hz due to several factors:

1. **Bass Guitar Frequency Spectrum:** These very low frequencies fall within the range of a bass guitar's frequency spectrum. Cutting frequencies below this threshold may result in lost harmonic content and could negatively impact the depth and character of your sound, even though the human ear has limited sensitivity in this range.

2. **Perceived Feel of the Low Frequencies:** Even though humans generally perceive pitch within a range of about 20 Hz to 20,000 Hz, frequencies below 40 Hz, while not necessarily heard as distinct pitches, contribute to the 'feel' of the bass. When played at high volumes, these frequencies can produce vibrations that listeners can physically feel, adding another sensory dimension to the audio experience.

3. **Harmonic Content and Richness**: Many musical instruments produce sounds that are complex and rich in harmonics. When a note is played on a bass guitar, it produces a fundamental frequency along with multiple harmonics. Some of these harmonics fall into the sub-40 Hz range, and though they may not always be heard distinctly, they contribute to the overall richness and complexity of the sound.

4. **Noise and Interference Importance:** Another consideration is that while it may seem advantageous to filter out potentially erroneous and unnecessary low-frequency noises, this isn't always desirable in a musical context. Some of these "noises" can subtly contribute to the overall tonal character of an instrument.

5. **Room Interaction:** Lower frequencies interact with the acoustics of a room differently than high frequencies do. They can cause interesting resonances and add complexity to the sound that would not otherwise be achieved. This applies even below 40Hz, where the fundamental frequencies of the room itself may come into play.

While it's true that many audio systems implement a high-pass filter to remove extremely low frequencies (generally perceived as sub-bass or infrasound), the choice to do so should be intentional, taking into account the trade-off between potentially desirable harmonic content and the risk of undesirable noise or speaker damage.

and

Sub and infra-frequencies refer to very low frequency sound waves, which are typically categorized as infrasound when it falls below 20 Hz, and sub-bass for the range of 20 to 60 Hz. They aren't typically heard by humans as much as they are felt, contributing to the experience of sound on a visceral and emotional level.

In music, sub and infra-frequencies play an equally important role. These low frequencies create a sensation that is 'felt' rather than 'heard', adding a physical component to the music. They provide the 'rumble' or 'thump' in music, delivering a fullness to the overall sound. In many types of music, such as dance, electronic, and drum and bass, these frequencies are crucial to the music's overall impact and character.

Concerts and nightclubs often use special speaker systems to project these low frequencies to allow the audience to 'feel' the music. There is a sense of immersion and physicality that infra-frequencies can facilitate in a live music setting, enhancing the collective experience.

Furthermore, for those with hearing impairments, these frequencies can be especially important. Deaf individuals can experience music through vibrations, with these low frequencies playing a crucial role. This provides an enriching way for them to participate in the musical experience.

Lastly, sub and infra-frequencies can function as communication infrastructures in several species, like elephants for instance. Though this is not directly linked to our typical understanding of music enjoyment, it's an interesting side note about how widespread this frequency range is used in nature, adding another layer to our appreciation for its importance.

In summary, while these infrasound and sub-bass frequencies might be out of the ordinary hearing range for humans, they significantly contribute to the richness and physicality of music, making them an essential element in musical enjoyment. They don't just allow us to hear music, but to 'feel' it, providing a multi-dimensional experience.
__________________________________________________________

Geezer Butler and Ashdown seem to understand this element:

Head Of Doom - Geezer Butler

And a schematic of Geezer's rig:

https://cdn.shopify.com/s/files/1/2397/1117/files/HOD_Tech_big_large.png?v=1510154946

Different strokes for different folks...

 

[agedhorse]

Yes, my direct experience disagrees with your premise. I find that most players prefer bass high passed between 30Hz and 50Hz, but some prefer higher.

Since most bass cabinets are 10dB down by 35Hz anyway, and are generating nothing but distortion and noise at that point (at gigging levels), most players find this to be unpleasant.

We will have to agree to disagree on this one.

 

[jb90]

From an acoustic engineering standpoint, that is a strong argument with great merit. From a psychoacoustic perspective, there can arise issues with "over filtering".

To save myself time I will submit some AI responses that are consistent with my academic understandings of and personal experience as a musician on the topic.

From a psychoacoustic perspective, a bass guitar amp should not filter frequencies below 40 Hz due to several factors:

1. **Bass Guitar Frequency Spectrum:** These very low frequencies fall within the range of a bass guitar's frequency spectrum. Cutting frequencies below this threshold may result in lost harmonic content and could negatively impact the depth and character of your sound, even though the human ear has limited sensitivity in this range.

2. **Perceived Feel of the Low Frequencies:** Even though humans generally perceive pitch within a range of about 20 Hz to 20,000 Hz, frequencies below 40 Hz, while not necessarily heard as distinct pitches, contribute to the 'feel' of the bass. When played at high volumes, these frequencies can produce vibrations that listeners can physically feel, adding another sensory dimension to the audio experience.

3. **Harmonic Content and Richness**: Many musical instruments produce sounds that are complex and rich in harmonics. When a note is played on a bass guitar, it produces a fundamental frequency along with multiple harmonics. Some of these harmonics fall into the sub-40 Hz range, and though they may not always be heard distinctly, they contribute to the overall richness and complexity of the sound.

4. **Noise and Interference Importance:** Another consideration is that while it may seem advantageous to filter out potentially erroneous and unnecessary low-frequency noises, this isn't always desirable in a musical context. Some of these "noises" can subtly contribute to the overall tonal character of an instrument.

5. **Room Interaction:** Lower frequencies interact with the acoustics of a room differently than high frequencies do. They can cause interesting resonances and add complexity to the sound that would not otherwise be achieved. This applies even below 40Hz, where the fundamental frequencies of the room itself may come into play.

While it's true that many audio systems implement a high-pass filter to remove extremely low frequencies (generally perceived as sub-bass or infrasound), the choice to do so should be intentional, taking into account the trade-off between potentially desirable harmonic content and the risk of undesirable noise or speaker damage.

and

Sub and infra-frequencies refer to very low frequency sound waves, which are typically categorized as infrasound when it falls below 20 Hz, and sub-bass for the range of 20 to 60 Hz. They aren't typically heard by humans as much as they are felt, contributing to the experience of sound on a visceral and emotional level.

In music, sub and infra-frequencies play an equally important role. These low frequencies create a sensation that is 'felt' rather than 'heard', adding a physical component to the music. They provide the 'rumble' or 'thump' in music, delivering a fullness to the overall sound. In many types of music, such as dance, electronic, and drum and bass, these frequencies are crucial to the music's overall impact and character.

Concerts and nightclubs often use special speaker systems to project these low frequencies to allow the audience to 'feel' the music. There is a sense of immersion and physicality that infra-frequencies can facilitate in a live music setting, enhancing the collective experience.

Furthermore, for those with hearing impairments, these frequencies can be especially important. Deaf individuals can experience music through vibrations, with these low frequencies playing a crucial role. This provides an enriching way for them to participate in the musical experience.

Lastly, sub and infra-frequencies can function as communication infrastructures in several species, like elephants for instance. Though this is not directly linked to our typical understanding of music enjoyment, it's an interesting side note about how widespread this frequency range is used in nature, adding another layer to our appreciation for its importance.

In summary, while these infrasound and sub-bass frequencies might be out of the ordinary hearing range for humans, they significantly contribute to the richness and physicality of music, making them an essential element in musical enjoyment. They don't just allow us to hear music, but to 'feel' it, providing a multi-dimensional experience.

1. You don't cut out everything with HPF help. It's a slope (steeper or less) not brickwall. And you can choose cutoff freq too. It's not "only 80hz-100hz-200hz".
2. Yes. It's true. But in a band situation or in a song mix many instruments live in 20-200hz range too. Maybe not so much but still. Many bass waves from different sources in so low frequencies make mud and unpleasant experience (in short).
3. Maybe with double bass but bass guitar lives mainly in 2nd harmonic and higher to even 16th harmonic. Funadamentals especially in below 50hz gives you more mud, more distortion from speakers and so on.
5. That's why HPF help to solve one of those problems quickly. Maybe not the best maybe not better but definitely one problem solved.
IMO that's why adjustable HPF/LPF exist. You can just cut 20hz and left 40hz untouchable. Every audio engineer say that compression is your friend when it comes to bass guitar. Why? Because under and overtones kill consistent tone of bass guitar! You don't need 20-20k flat for bass guitar. Same with LPF. You probably won't hear P-bass on flats in 10k+ range anyway. Everything will be possible if bass rigs will be enormous (enormous poweramps and especially enormous cabs with expensive, well-made speakers especially prepared for reproduce subbass with great loudness, without distortion and so on). I'm not an audio engineer but I talked to many of them and you can learn a lot from those experience people. What you wrote here is article about how the sound behaves in general. With bass guitar, bass amplification, music production and so on it looks somewhat different.

 

[Akiyama]

Yes, my direct experience disagrees with your premise. I find that most players prefer bass high passed between 30Hz and 50Hz, but some prefer higher.

Since most bass cabinets are 10dB down by 35Hz anyway, and are generating nothing but distortion and noise at that point (at gigging levels), most players find this to be unpleasant.

We will have to agree to disagree on this one.

1. You don't cut out everything with HPF help. It's a slope (steeper or less) not brickwall. And you can choose cutoff freq too. It's not "only 80hz-100hz-200hz".
2. Yes. It's true. But in a band situation or in a song mix many instruments live in 20-200hz range too. Maybe not so much but still. Many bass waves from different sources in so low frequencies make mud and unpleasant experience (in short).
3. Maybe with double bass but bass guitar lives mainly in 2nd harmonic and higher to even 16th harmonic. Funadamentals especially in below 50hz gives you more mud, more distortion from speakers and so on.
5. That's why HPF help to solve one of those problems quickly. Maybe not the best maybe not better but definitely one problem solved.
IMO that's why adjustable HPF/LPF exist. You can just cut 20hz and left 40hz untouchable. Every audio engineer say that compression is your friend when it comes to bass guitar. Why? Because under and overtones kill consistent tone of bass guitar! You don't need 20-20k flat for bass guitar. Same with LPF. You probably won't hear P-bass on flats in 10k+ range anyway. Everything will be possible if bass rigs will be enormous (enormous poweramps and especially enormous cabs with expensive, well-made speakers especially prepared for reproduce subbass with great loudness, without distortion and so on). I'm not an audio engineer but I talked to many of them and you can learn a lot from those experience people. What you wrote here is article about how the sound behaves in general. With bass guitar, bass amplification, music production and so on it looks somewhat different.

I will quote myself as it seems to have been passed over. "From an acoustic engineering standpoint, that [HPF/LPF] is a strong argument with great merit. From a psychoacoustic perspective, there can arise issues with "over filtering"."

Also, the listeners' experience (psychoacoustics) does not seem to be taken into consideration by your responses, only engineering and players' perspectives. Is music only meant for the players and engineers? I have provided the science-based rationale, from a psychoacoustic perspective, to care being applied to filtering. Perhaps there is a miscommunication?

edit: cleaned up some sentence ordering

 

[agedhorse]

Psychoacoustic perspective can result in both positive and negative effects, it’s not always positive.

 

[Kerry Brown]

It's a simple thing for me. I like my tone better with an HPF at around 30 to 40 Hz. Exactly where depends on the bass, amp, and speakers.

 

[JMX]

That's what I like about my Eden Navigator preamp. The Low can be used as a HPF (35 Hz shelf), the Treble as a LPF (15 kHz shelf). There is a fixed 15 kHz LPF built-in anyway, so you can neutralise it or reinforce it with the Treble.

 

[Passinwind]

I will quote myself as it seems to have been passed over. "From an acoustic engineering standpoint, that [HPF/LPF] is a strong argument with great merit. From a psychoacoustic perspective, there can arise issues with "over filtering"."

Also, the listeners' experience (psychoacoustics) does not seem to be taken into consideration by your responses, only engineering and players' perspectives. Is music only meant for the players and engineers? I have provided the science-based rationale, from a psychoacoustic perspective, to care being applied to filtering. Perhaps there is a miscommunication?

AI, really? I'm not seeing science based rationale, with any cites, just yet another hot take opinion. Nothing wrong with that though!

 

[Karl Kaminski]

"From an acoustic engineering standpoint," while that may be your perspective it may not be the general use-case/need of this forum for (what I would guess is) the majority of members? And while a case may be made for the larger topic for conversation, real-life experience and live-sound production problem solving is probably the goal of most here.

I use HPF as a problem-solver for difficult room acoustics it can float between 30-80hz depending on room/instrument/setup/group. If you're producing a form of music (electronic/binaural beat/etc) to be listened to at home/in-car/headphones, the effect and affect of not taming (or taming) those freqs may be different and/or be a different goal entirely.

 

[djmay]

AI, really? I'm not seeing science based rationale, with any cites, just yet another hot take opinion. Nothing wrong with that though!

You are very kind. I would say the AI content is mass-produced plagiarism, in addition to being subjective.

 

[Passinwind]

You are very kind. I would say the AI content is mass-produced plagiarism, in addition to being subjective.

If it's any good it's already learned from our responses though, at least.

 

[agedhorse]

That's what I like about my Eden Navigator preamp. The Low can be used as a HPF (35 Hz shelf), the Treble as a LPF (15 kHz shelf). There is a fixed 15 kHz LPF built-in anyway, so you can neutralise it or reinforce it with the Treble.

IMO (based on the circuit itself), they are really fairly conventional Bass-Treble shelving filters, the 35Hz and 15kHz figures are not reflective of the corner frequencies (actually closer to 100Hz and ~5kHz depending on the amount of cut-boost), and also the slope is 6dB/octave (where an effective HPF is 18-24dB/octave).

HOW these frequencies are specified is DIFFERENT from how HPF frequencies are specified since the filters are very different.

 

[agedhorse]

"From an acoustic engineering standpoint," while that may be your perspective it may not be the general use-case/need of this forum for (what I would guess is) the majority of members? And while a case may be made for the larger topic for conversation, real-life experience and live-sound production problem solving is probably the goal of most here.

I use HPF as a problem-solver for difficult room acoustics it can float between 30-80hz depending on room/instrument/setup/group. If you're producing a form of music (electronic/binaural beat/etc) to be listened to at home/in-car/headphones, the effect and affect of not taming (or taming) those freqs may be different and/or be a different goal entirely.

Even from an acoustic engineering perspective, HPF's are VERY useful tools used to optimize the performance of an acoustic space and the speakers used within them. Since my degree is in EE and I studied acoustics as part of the curriculum, I stand by my opinion.

 

[JMX]

agedhorse, I agree, it seems more like an unintended benefit, it seems to work OK.

I usually do use a decidated HPF/LPF (Schalltechnik04 Vong Filter), since I switch back and forth between two rack preamps. Aditionally, there's a variable HPF in my Yamaha P3500S.