Materials for cylindrical subwofers ?

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Hello,
The French did do some test with sand filled enclosures. It appears that if you want the sand to work the enclosure should not be to thick so it will vibrate BUT then this vibration will be stopped by the sand.
So if you could find two pvc tubes with different diameters so you can have like 2 or 3 centimeters of sand in between that could work perfectly.
The problem is probably finding these tubes!
Greetings. Ed
 
PVC.

Hi academia,

PVC pipe works great. I have made several subwoofers using PVC. Here is one that I started last year.Two LAB12s and PVC pipe build.. I recently removed this sub to go in a different direction.
Still going to use PVC pipe, but will go back to a closed box again. I should add that the 14" schedule 40 pipe that I'm using is expensive, all of the pipe was free to me from dumpster diving :D.

Regards,
Matt
 
Hello,
The French did do some test with sand filled enclosures. It appears that if you want the sand to work the enclosure should not be to thick so it will vibrate BUT then this vibration will be stopped by the sand.
So if you could find two pvc tubes with different diameters so you can have like 2 or 3 centimeters of sand in between that could work perfectly.
The problem is probably finding these tubes!
Greetings. Ed


Hello Eduard

Good solution, fill with sand between different diamentros of tubes .... but the cost goes up and the work increases.
It seems that I get 2.8 mm thick tubes here, that's very thin ......
For my 18-inch speaker the tube would be 0.60 meters in internal diameter x 1 meter in height. I think with some internal reinforcements it could work.

Something like that :
 

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Both sonotubes and sewer pipes can be used. The rolloff edges are not as sharp as a box design, probably because of wall flex along the length of the tube. They look unusual and sound good.

SonoTube and SewerPipe BP6 Subwoofer


Hello DonVK


Yes, the problem is the flexion of the walls ...

I think aluminum is rigid, but how often will it resonate?

The subwofer will be sealed .....:D
 
Hi academia,

PVC pipe works great. I have made several subwoofers using PVC. Here is one that I started last year.Two LAB12s and PVC pipe build.. I recently removed this sub to go in a different direction.
Still going to use PVC pipe, but will go back to a closed box again. I should add that the 14" schedule 40 pipe that I'm using is expensive, all of the pipe was free to me from dumpster diving :D.

Regards,
Matt
Hi Matt

Well, I wish I could have that luck :)!

That is a tube with very thick walls ! :D
 
If you have the appropriate gear, you could always record yourself striking the prospective tube & scan the audio signal with an oscilloscope & note the frequencies?



-----------------------------------------------------------------------Rick........

Yes, that is a correct technical solution.

But I do not have the instruments, and it would be impractical ....;)
 
Here is the latest PVC subwoofer. I made 2 of them using 14" couplings and 12" NVX subwoofers. The only brace needed was for the back to stiffen the MDF. Once I get the MiniDSP running I will apply an LT. I need to finish the feet then paint them. I have already started the enclosure for the LAB 12s. The new build will be only 3 feet long and have cleaner lines. Still keeping with the opposed layout for force canceling. Good luck with your project.

Regards,
Matt
 

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Here is the latest PVC subwoofer. I made 2 of them using 14" couplings and 12" NVX subwoofers. The only brace needed was for the back to stiffen the MDF. Once I get the MiniDSP running I will apply an LT. I need to finish the feet then paint them. I have already started the enclosure for the LAB 12s. The new build will be only 3 feet long and have cleaner lines. Still keeping with the opposed layout for force canceling. Good luck with your project.

Regards,
Matt

I think it will not be easy but I should find PVC pipes with wall thicknesses like the one I see in the photograph. I imagine around 12 mm ..... that will be enough for me ....
Thanks for your wishes ! :)
 
What happens with the aluminum tubes ?

Apparently they can be used without major resonance problems and can always be internally lined with bituminous membranes, and on top of this foam rubber, polyester fiber, etc ...

How to Make a DIY Cylinder Subwoofer (AKA Sonosub) | Spinditty




" The cylinder was made from aluminium ducting pipe, lined inside and out with foam, with mdf endcaps. This shows the ducting pipe, it's 18 inch in diameter. In the background is the 6 inch drainage pipe that I used for the ports and you can also see the driver."


What do you think of this project ? what are the drawbacks here? Yes, I know it's a little long pipe ....
 
I used 5mm wall thickness 10" diameter steel pipes and welded a 10mm steel backplate and 10mm steel ring to accept the driver. Of course these sounded horrible in that state and rang like a bell.

Next I lined the interior with aluminium lined automotive panel deadener and experimented quite a bit with stuffing materials, quantities and positions. This sounded much, much better, but if I gave it the knuckle test the pipe still would ring a little.

Third step was to externally brace the tube and apply pre-tension to the walls. This was extremely successful...the result is a very inert cabinet that passes a knuckle test better than an overbuilt and very inert pair of 2 way standmounts. The time of settlement also measures less but interestingly is the same as rapping a double brick wall...so the steel tubes can be very inert.
 
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