Infrasonic pipe

Elonmuss

Member
2022-08-02 9:07 pm
Hello experts I'm new to the forum, I'm French and I want your help regarding a project. So I state that I have been following you for a long time but I have never found a discussion that was right for me so I decided to create one. I would like to make an infrasound generator of the pipe type, which consist of a large tube, with a fan or subwoofer at one end and with the effect of the resonance infrasounds are created, I want to know from you, what the size must be (length and width) of the tube? can he fold in on himself? here I leave with these questions, I hope you can help me, thanks
 
Infrasonic/infra-bass = < 20 Hz, so how low do you want to go?

Regardless, the basic pipe length (m) is ~344 m_sec/4/?? Hz minus the pipe's end correction = at least ~radius*0.613, but not really an issue for your app unless wanting to keep it as small as practical.

It's cross sectional area (CSA) is a function of desired driver size/type and how much gain bandwidth (BW) you want. As a general rule a 2:1 compression ratio is the norm for a constant expansion/cylindrical, square or rectangular pipe, though could be 3:1 like some bass horn drivers can tolerate or even a compression driver's 10:1 in the form of an inverse tapered TQWT (I've even used up to 20:1 if the motor is powerful enough, though not in the infra-bass).

Yes, you can fold it up as much and at any direction as you want, though it will need to be longer due to bend losses (assuming you want a tight bend radius) that I don't know how to calculate, so personally would have to make it obviously too long to compensate.
 
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Interesting. Just yesterday a cliebt sent a video of a system he designed to be able to produce sound for a full scale digital organ. I have not wtched it, but this guy was/is on th eground in the particular goal you wish to achieve.

I have not watched it yet, and he intended the system to be portable (a tight restraint).


dave
 
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Elonmuss

Member
2022-08-02 9:07 pm
Infrasonic/infra-bass = < 20 Hz, so how low do you want to go?

Regardless, the basic pipe length (m) is ~344 m_sec/4/?? Hz minus the pipe's end correction = at least ~radius*0.613, but not really an issue for your app unless wanting to keep it as small as practical.

It's cross sectional area (CSA) is a function of desired driver size/type and how much gain bandwidth (BW) you want. As a general rule a 2:1 compression ratio is the norm for a constant expansion/cylindrical, square or rectangular pipe, though could be 3:1 like some bass horn drivers can tolerate or even a compression driver's 10:1 in the form of an inverse tapered TQWT (I've even used up to 20:1 if the motor is powerful enough, though not in the infra-bass).

Yes, you can fold it up as much and at any direction as you want, though it will need to be longer due to bend losses (assuming you want a tight bend radius) that I don't know how to calculate, so personally would have to make it obviously too long to compensate.
wow what a complete answer, then yes I too had thought about the organ pipes also because based on the material it can resonate better if it is brass it is better then the frequency I would like to reach is 10 hz, the pipe I have to bend it obviously, so I calculate to create a tube I don't know them but if you let me know I can solve them. so for that frequency how long and wide should the tube be? which material is the best?
 

Elonmuss

Member
2022-08-02 9:07 pm
Interesting. Just yesterday a cliebt sent a video of a system he designed to be able to produce sound for a full scale digital organ. I have not wtched it, but this guy was/is on th eground in the particular goal you wish to achieve.

I have not watched it yet, and he intended the system to be portable (a tight restraint).


dave
do you think these big speakers with subwoofer can generate infrasound? if they were a little smaller it would be a good idea but I think that besides being big they are also very heavy
 
do you think these big speakers with subwoofer can generate infrasound?
Generating sound at 20Hz or below is possible with any speaker.
Generating SPL (sound pressure level) capable of being heard by ear, or felt in your body is a different prospect.
The SPL to detect VFL (very low frequencies) varies by individual, and the SPL of the VLF may vary radically around a room.
Around 80dB SPL at 20 Hz will be detected by most people, while at 10Hz, the SPL may need to be 100dB, 20dB (100 times) the power.

A description of what you plan to use the speaker for, size restraints, room dimensions and construction would help inform what SPL and frequency range is required, and the most cost-effective route to accomplish that.

Art
 
Hello experts I'm new to the forum, I'm French and I want your help regarding a project. So I state that I have been following you for a long time but I have never found a discussion that was right for me so I decided to create one. I would like to make an infrasound generator of the pipe type, which consist of a large tube, with a fan or subwoofer at one end and with the effect of the resonance infrasounds are created, I want to know from you, what the size must be (length and width) of the tube? can he fold in on himself? here I leave with these questions, I hope you can help me, thanks
Good evening Elonmuss. I designed the system in the video that Dave referenced.

GM said out loud the very first thing that came to my mind: Infrasonic is anything lower than 20Hz so how low (and loud) do you want to go? I would also ask: What are you trying to accomplish?

In organ building, we say “the most important stop on the organ is the room.” This sentiment is true in hifi with the relationship between speakers and the room too.

I try to hold in awareness that sound is energy, and frequency is based on wavelength. A room can only handle so much energy, but the tricky part is understanding how the unique energy pattern of your speaker system activates the unique sonic characteristics of your room. Since wavelength is imho the most important consideration, and low frequencies are uniquely difficult to deal with, I come back to ask, what are you trying to accomplish? What audio material exists in the single digit range you’re missing out on?

For my purposes, I legitimately needed to reach 16hz to reproduce low “C” of a 32’ organ pipe. Reason being is because digital organs usually have a few 32’ stops that undergird the entire instrument since overtones (harmonics) go up. In a church, it’s longest dimension is long enough to actually hear 16Hz as the wave has the room to develop and flow past your ears. Also, the size of the bass cabinets aren’t restricted by physical space so an optimal cabinet size can be made with out compromise or “trickery.” A driver with a low Fs in a big ol’ box (designed properly of course) will do the job.

The same setup in a residence would not work the same because of a million reasons, but with regards to bass, you are limited to the longest dimension of the room. Once 1/4 of the wavelength becomes longer than the room, it becomes something you can feel in terms of compression, but you can’t actually hear it. The waves don’t tug on your ears, it’s more like you’re inside the speaker cabinet at that point.

Again, since diy audio is based on goals, high SPL or flat response may not be the design goal. I don’t know what you are trying to achieve in the single digit range, but it is true that a 64’ organ pipe is essentially 8hz. The bend in the pipe they mentioned is what we call mitering. It keeps the speaking length of the pipe intact, but folds the pipe so it can physically fit into a given space, much like a trumpet is curly so it can fit in your hand.

Musically speaking, a 64’ pipe is virtually impossible to accurately digitally emulate. The pipes grow exponentially as you’ll notice pipes are not in a straight line, they are along curve and change in both height and width. This is called “scaling” and figured by a method called 1/17th halving, meaning every 17th pipe is 1/2 the diameterAll that to say that again, it’s all about wavelength, and as you go lower in pitch, the wavelength grows exponentially. In turn, so do conventional subwoofer cabinets the lower you go.

I would say that if you knew how low you wanted to go, and the SPL you need to achieve to meet your goals, you have a direction on what equipment you’ll need to reach your goal. I wasn’t building speakers for 2 channel HIFI, Theatre, or Pro Audio, so “the rules” of best practice in those industries look different than mine. Yours may also be unique!.

Then there’s that pesky thing called a budget that gets in the way :).

I don’t have the mathematics or engineering background represented in this community, but I’ve tried a lot of things until I was happy! I hope that helps.
 
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Elonmuss

Member
2022-08-02 9:07 pm
The client certainly suggested it would adequaetly do the low note on the organ, 16 Hz. If he only has the 4 large woofers it may not be able to play really really loud.

I pinged the designer. Hopefully he has some answers for you.

dave
so sorry but due to the translation you don't understand much. so are you telling me that with the organ pipe we got to 16 hz, but with the speakers the 4 woofers are not enough to get to infrasound?
 

Elonmuss

Member
2022-08-02 9:07 pm
Generating sound at 20Hz or below is possible with any speaker.
Generating SPL (sound pressure level) capable of being heard by ear, or felt in your body is a different prospect.
The SPL to detect VFL (very low frequencies) varies by individual, and the SPL of the VLF may vary radically around a room.
Around 80dB SPL at 20 Hz will be detected by most people, while at 10Hz, the SPL may need to be 100dB, 20dB (100 times) the power.

A description of what you plan to use the speaker for, size restraints, room dimensions and construction would help inform what SPL and frequency range is required, and the most cost-effective route to accomplish that.

Art
then on the web, a long time ago I saw a very large loudspeaker we are talking about a height greater than 2 meters with a weight greater than 1 ton and that could reach about 5 hz, so I believe that loudspeakers to generate infrasound, are inconvenient from the point from a logistic point of view
 

Elonmuss

Member
2022-08-02 9:07 pm
incredible dante you gave a very complete answer ache do not know the formulas well but in math I am fine. however ip I would like to reach 10 hz, furthermore the use I would like to make of it is both in a very small room (10m ^ 2) and outdoors, but the most important thing is that the infrasound generator can be very close to me about 1 meter away, so it is easier to build it, so summing up the generator (pipe or speaker) must not be far from me, but close to 1 meter away, unfortunately the construction of the speakers with subwoofers is inconvenient for me also because I would like it to be a minimum transportable, and therefore I believe that the tube is the best choice. so knowing my needs and that the generator must be 1 meter away from me, which choice is the best? i am more for the tube
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
@Elonmuss , please check your translator software settings.

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