Materials for cylindrical subwofers ?

[academia50]

I have not been able to get any appropriate tube yet ....

The iron cylinder is discarded, it is too heavy to manipulate and although I appreciate the opinion of weltersys, (see post 34) I have been consulting the web and I can not find definitive opinions about it.

Materials for cylindrical subwofers ?

Shielding the speaker magnet is a complication and there is no reliable information to do it correctly. And personally I'm a bit apprehensive to know that iron (highly magnetic material) is so close to the pole piece.

Cardboard tubes similar to the Sonotube of large dimensions are not manufactured here.

Large PVC pipes (for sewers) are not sold fractionally and I do not have the time to go through roadworks to see if someone discards a piece of the six meters long that the manufacturers provide.


So I have two options left. Build the box in wood in the form of an octahedron or use .......... this ! :


https://articulo.mercadolibre.com.a...ion-recommendations/element&c_element_order=1

It is a polyethylene water tank in three layers, which makes it very resistant to internal pressures, but the thickness of the wall is very thin, so it does not have the rigidity of PVC.

I thought to cover the walls with lead sheets and a reinforcement in the center of the cylinder.


https://articulo.mercadolibre.com.a...hapas-para-rayos-x-sanatorios-espesor-1mm-_JM

What do you think ? Will it have the necessary rigidity or will it still vibrate with low frequencies ?

All opinions are highly valued, as always.

 

[GM]

Re shielding: https://www.reddit.com/r/Electromag...shielding_galvanized_steel_partially_shields/

GM

 

[GM]

Cardboard tubes similar to the Sonotube of large dimensions are not manufactured here.

Really?! How do they make poured concrete columns?

GM

 

[hollowboy]

Large PVC pipes (for sewers) are not sold fractionally and I do not have the time to go through roadworks to see if someone discards a piece of the six meters long that the manufacturers provide.

You could try local trade websites and salvage yards.

So I have two options left. Build the box in wood in the form of an octahedron

I know what you mean, but the term is octagonal prism.

If I was building it, I'd decide on how many sides the prism should have (6, 8, 12 whatever...) based on the materials and tools on hand. e.g. if you already own a 22.5 degree router bit, a 16 sided prism might make more sense.

Yonico 13913q Chamfer Edge Forming Router Bit - 22.5 Degree - 1/4 Shank | eBay

or use [...] a polyethylene water tank in three layers, which makes it very resistant to internal pressures, but the thickness of the wall is very thin, so it does not have the rigidity of PVC.

I thought to cover the walls with lead sheets and a reinforcement in the center of the cylinder.

I think anything will do, if you reinforce it.

2 other options:

1) Used ~220 litre plastic drums (for shipping olives etc) go for about 1/3 that price. The drums are often ribbed, and are build for transport, so I suspect they'd be stronger than a static smooth-walled water tank.

2) DIY cylinder with bendy ply.

 

[academia50]

Really?! How do they make poured concrete columns?

GM

As far as I know, PVC pipes are used here, I do not know if it is because it better resists the internal pressure of the filling material (cement, iron rods, pebbles, etc.) than the cardboard or simply because nobody makes the latter. in large measures. When the columns are not round, wood is still used.....

 

[academia50]

Re shielding: [SHIELDING] Galvanized steel partially shields magnetic fields : Electromagnetics

GM

Thanks for the link, but I already discard the use of iron cylinders. My spine should not try so hard, it already has a few miles traveled ...:RE

 

[academia50]

I know what you mean, but the term is octagonal prism.

I really meant orthopedic, sorry.
I have a router and the different types of cutting pieces, but it is very complicated, thanks anyway. (I'm a bit (too much?) lazy, I know ...


The orthohedron: Surface area and volume - Geometry

2 other options:

1) Used ~220 litre plastic drums (for shipping olives etc) go for about 1/3 that price. The drums are often ribbed, and are build for transport, so I suspect they'd be stronger than a static smooth-walled water tank.

2) DIY cylinder with bendy ply.

1) I will explore that option, also if I decide for the water tank I will build internal reinforcements


2) I have seen that construction, I think it would be a great job, and perhaps the best option for a DIY cylinder!
And the best looking (although that goes in tastes ...)


Thanks again for all, friend !