[jimstewart]

So I mentioned to a few people about this subwoofer project. 2 48" x 22" sealed tempest x sonotube.


One guy I talked to that years ago built and sold speaker commercially said "sonotube's leak bass badly, you need to wrap that in lamanite like fermical to strengthen the paper. Better than that use a medium size drain tile (concrete or something pipe) and a 3/4 inch layer of shower board (concrete with fiberglass scrim) between 2 layer of plywood (he may have said BB) on either end to seal it up.


This made me question the whole unbraced paper tube 3/10 of inch thick. I was already planning to put some internal radial braces in.


Any other ideas?

 

[Willd]

This is unnecessary. The tubes are designed to handle enormous pressure/weight from concrete. They don't have inherent problems with leaking. As long as one uses proper endcaps and ensures they fit well and if necessary, seals them with caulk/liquid nails, there will be no problems with leaking.

 

[MKtheater]

I agree, the sonotubes are incredible, they suprise me everytime I fire them up. Very strong and no need to add anything to them, except endcaps.

 

[jimstewart]



Quote:
Originally Posted by Willd /forum/post/14180196


This is unnecessary. The tubes are designed to handle enormous pressure/weight from concrete. They don't have inherent problems with leaking. As long as one uses proper end caps and ensures they fit well and if necessary, seals them with caulk/liquid nails, there will be no problems with leaking.

You have got to be the 5th person to tell me this. And I have looked at a lot of the other sonotubes on this forum built with no internal bracing. But I can wrap my arms around a sonotube and crush it with my own strength (I did it to an 18" tube after someone kept telling me how strong they were). I have heard that the tubes are so strong bla bla bla if I thought that was the case I wouldn't be asking for way to reinforce them.

The side walls of a sonotube are meant to hold up against pressure from concrete there not meant to withstand vibration. If you think that there is no energy storage inherent in a sonotube, knock one down and watch it bounce all over the place.

I have also seen a few sonotube subs built with an inner and and outer tube with the gap between filled with sand. 100's of lbs of sand. If this didn't do anything why would someone go to all the trouble........

So again any idea's on reinforcing sonotubes?

 

[malovich]

Sonosub tubes are weak when squeezed by your arms because you create inherent pressure points. As an example, a pop can can support anywhere from 30-50psi internally but when empty, a toddler can badly deform them. Sonosubs work great because of their round nature and the pressure inside them is evenly distributed and the cardboard is subjected to a purely tensile force. See the wiki page on Pressure Vessels for more information.

 

[penngray]



Quote:
You have got to be the 5th person to tell me this........So again any idea's on reinforcing sonotubes?

Why can you not just trust those 5 people? Will, MK and all those who have built Sonotubes have never used bracing so just trust that as fact and complete the build.


I have no idea how you brace something round because even if you brace a "section" you can squeeze above and below that section and still damage the tube.


Btw, how thick is your sonotube wall??

 

[OvalNut]

The crushing pressure described by hugging it would be applied from the outside pressing inward. This is not how the pressure is applied to the wall of the enclosure of a sub. With a sub, the pressure is applied from the inside pressing outward. It is an even pressure, and the wall has nowhere to flex. This is the same concept as is applied with highly pressurized aerosol and gas containers. And, this is why the sonotube is effective for containing the weight of concrete pours. It retains it's shape when the pressure is exerted evenly to the whole inside wall and pressing outward. It's just physics.


I do know that some people will want to reinforce the area around the driver so that it's mounting is secured and immobile, but the upper walls of the sonotube really do not require bracing.



Tim

 

[ransac]

Seems you are being a little stubborn on this point. Besides all the DIY sonotubes people have built without bracing, some posting here, HSU used to and SVS does build commercial cylinder subs without internal bracing, except for the end caps. SVS has even cut out part of the sidewall and mounted an amp. One guy, used to, several years ago, says sonotubes leak bass. With a proper seal at the top and bottom, just how would bass leak out?

 

[MKtheater]

All I know is that I have owned many well known and excellent subs and my leaky, unbraced sonotubes sound better, more powerful, and more viceral. You can try to brace them all you want, it is up to you.

 

[Bob7145]

If you are really concerned about strength you might try using schedule 40 or 80 PVC water pipe. Available in 24" and 30" diameters.

 

[mynym]

Question for you cardboard tube owners. When the bass hits can you feel a form of vibration on the outside of the tube? If so, your enclosure is not as efficient as it could be.


There is a reason the car audio DB Drag guys fill their door panels with concrete. They are all about efficiency of the enclosure, making it as stiff as possible.


From a physics point of view given equal SUBSTAINED pressure to all sidewalls in a cylinder shape the enclosure will yield formidable results. Using it to retain concrete, compressed gas/liquid is a good example of substained equal pressure.


However given the use case we have for adapting it to UNSUBSTAINED sound pressure for use of subwoofers which dynamically produce unequal amounts of sound pressure my hypothesis is that this may truly not be the optimal enclosure as the pressure inside the cavern varies. Also given the size of these enclosures even with minimal vibration from the cabinet flexing this reduces the efficiency of the cabinet. This alters the characteristics of the enclosure creating a less than ideal efficient cabinet housing the driver.


A real world example of this concept: If you look at submersive deep sea vehicles they are typically round or oval shaped. Given pressure equalization this oval/round hull can handle amazing amounts of pressure. However if a submarine dives to quickly and the pressure is unable to equalize it is unable to adapt to SUSTAINABLE pressure. The integrity of the cylindrical exoskeleton is compromised. I am sure we all remember the U-571 movie scene where the sub was diving to quickly and the pressure inside wasn't equalized fast enough.


If however the rigidity of the cylinder is increases by thickness and/or internal spoke like bracing is added, pulling in the enclosure equally to add strength, I would agree a cylinder is a perfect choice for a subwoofer enclosure.


With that said, there are obviously some pretty large benefits to SonoTubes: light weight, ease of construction, price, less standing waves.


Just my 2 cents.

 

[MKtheater]

Again, if it is not the best enclosure for bass or if it leaks bass, you cares, the bass I am getting from mine is reference quality and much better than mutiple svs box subs I have used as well as Klipsch thx ultra 2 subs. Nothing is perfect and if you can find me a better box sub or whatever for $1400 that will compete with my sub system than I will try it out. The cylinder does not need bracing, the guys that argue that it does have you ever heard a sonotube with a good driver? I hit 126 db's on multiple scenes on multiple movies and I have them turned down. I have put a SVSpb12/plus sub in the same position and it would take 8 of them to achieve that. The SVS does not vibrate. Just because the Svs does not vibrate does not mean that it will sound better, it is not even close. If you want to brace it go ahead, it is your time and money, but not needed.

 

[ransac]

In this application, we aren't talking about 100 PSI, but very small pressure levels. All sonotubes I have seen are also ported, so you can't build internal pressure. What pressure is built up is done evenly inside the enclosure. The material used doesn't stretch making this shape almost ideal, sonically more than aesthetically.

 

[jimstewart]

I understand that many have built unbraced sonotubes.........


I'm sure they sound fine......


The paper on my 22" tube is 3/10s of an inch thick.


The pressure vessel effect is note worthy and the shape is the only reason one could actually use a material that is so thin.


The 5 people that told me the tube was fine A have never built a sonotube sub before. And B haven't done any testing to support there assumptions.


The idea that the structure bore vibration of a particular material are not an issue because of its shape is TOTALLY ridiculous.


The walls of the sonotube will be exposed to pressure vessel like effects but they will also vibrate. This vibration will manifest itself in one very important way OUTPUT. The re radiation of old acoustic information. This information is undesirable, unpredictable and unwanted.


I'm sure as I have said that most sound fine. Back in my teens when I helped friends with car and home audio projects I found all kinds of interesting things. Like 12" sub woofers in boxes made from 1/2 mdf ........that sounded fine. Does that mean it was the best construction method CERTAINLY not.


I have been to SVS and had a factory tour, they make a nice product for an awesome price. The tube they use is smaller in every way from what I'm using except for its wall thickness which I be leave was a little thicker. So the comparison is oranges to grapefruits.



If you have built a sonotube sub woofer and totally disagree with me try this.

Play some music with a lot of nice cords down low, something with a lot of overtones so as to get a nice smattering of different frequencies. Turn it up and put you hand on the sub.......the sides will be vibrating.....keeping in mind that even the most modest sonotubes have surface areas many factors larger than the drivers in them.


A little wall movement equals a lot of acoustical energy leaking out. Its not a hole in the boat its the whole boat.


Any body got and hull strengthening idears?

 

[OvalNut]



Quote:
Any body got and hull strengthening idears?

Yep. For you Jim, I'd say build a box then.



Tim

 

[MKtheater]

I have a better idea, why don't you built one and test yourself. You are assuming with no experience. So you are saying that the vibration means that you leak bass which means you lose output. Even if this is right My one sonotube with all its leaky bass and lowered ouput will output more bass than most commercial subs in boxes. So the vibration means nothing. It cost me $1400 to build 4 18 inch driver tubes with amps and it will output more than any commercial sub(box), so again what is the problem with output?

 

[penngray]



Quote:
The paper on my 22" tube is 3/10s of an inch thick.

The wall is 3/10s of an inch? that doesnt seem right, I have some tubes on order so I can not confirm.

Quote:
If you have built a sonotube sub woofer and totally disagree with me try this.

Play some music with a lot of nice cords down low, something with a lot of overtones so as to get a nice smattering of different frequencies. Turn it up and put you hand on the sub.......the sides will be vibrating.....keeping in mind that even the most modest sonotubes have surface areas many factors larger than the drivers in them.

Honestly, Even if this had some truth NO one that owns a sonotube is going to care only because their subs kick ass in so many ways and I do believe the play music as well as HT.


Flexing walls just seems like you have the "thin" sonotube which might not be the right product.

 

[jimstewart]

hehe W/E Nascar nation doesn't surprise me that you don't understand.


The thickness of the 22 inch tube is 3/10 of an inch.....called a 300 wall in the business of concrete.


And man isnt the whole thing just tired. I already own the paper, so I obviously beleave in the concept.


I WAS SIMPLY ASKING FOR ADVICE ON TAKING IT TO THE NEXT LEVEL.


I love all this "I didn't do it so its not necessary" talk.......


I didn't ask if it was a good idea.


I asked for Ideas.........(and per usually with online forums got little 2 nothing)


Whatever I gave up on this "community" for ideas. I Decided that the concept of using laminate for the exterior of the tube, could be implemented at a later time if I felt it is necessary.


As for my tubes I put 2 radial braces in one enclosure and 4 in the other....the one with 2 got 8lbs of sound proffing compound, the one with 4 got no vibration related treatment. Both received a complete covering of R-30 insulation. The bead liner I used to paint the ends looks and worked great. After I finish them I will post my results.

 

[jimstewart]



Quote:
Originally Posted by penngray /forum/post/14186322


Honestly, Even if this had some truth NO one that owns a sonotube is going to care only because their subs kick ass in so many ways and I do believe the play music as well as HT.


Flexing walls just seems like you have the "thin" sonotube which might not be the right product.

All speaker enclosures flex. Even little bookshelf speakers with 5 inch woofers and 1.5 inch thick walls still flex. Its all a question of degree obviously. The walls of that bookshelf speakers do a very good job at keeping in that extraneous sound from getting out but there not perfect. The paper walls of a tube are also not perfect.


And again as i have previously stated, I know the sonotubes rule. But why not build the best enclosure I can? I have access to a full wood shop/welder/paint booth. SO I am ready and willing to get that last 5 or 10 % ......If other don't see a need for it fine. But God damn what up with the avalanche of don't bother...all cause I disagree with what is commonly excepted.

 

[OvalNut]

Now this is funny....


The esteemed members of this forum may well just enjoy seeing the following unsolicited Private Message sent to me less than an hour ago by the oh so sophisticated jimstewart. Here is a screen capture of his message in my Inbox here at AVS:

Nice.



Tim