Sub Enclosure made out of concrete

[Rafal]

Hi All,

I'm planning to build a HIFI sub (still not sure which design to go with (Maybe Rythmic or PE Dayton Titanic 10"))
I have an idea of making the enclousure out of poured fiber concrete. This would make it easier to make curved walls and the box would be very solid and "dead" sounding (I hope). has anyone done something like this? Are there any resources you can point me to or comment on the idea in general?

Thanks,

Rafal

[Peter Daniel]

How about using bricks and concrete?
http://www.royaldevice.com/customita...20sala%20audio

[Ed LaFontaine]

I've worked in construction for 28 years. Placed many, many cubic yards of concrete. Your intro leaves much to speculation. Please describe the enclosure you have in mind and we'll go from there.

We can discuss the merits of "fiber" reinforcement if your wish. Concrete alone has a tensile strength of 5-600 psi (or more). Fibers (steel or poly) add little to this unless used in ridiculously high doses.

You will need a model of your driver (at least the opening) to cast into the mold.

Normal concrete weighs ~150 pounds/ cubic foot. It will be heavy!

The mold will need to be constructed with a removable interior. Wood forms can be frustrating for the novice. And you have to be able to think in reverse. Foam may be a better option. A combination of foam and wood could be made to work. A "staged" construction may be necessary to stabilize the interior form. That is, place up to the lower third of the mold, let it set, then place the remainder. Care will be required to ensure a bond at the construction joint.

We are talking monolythic here. An option would be to pre-cast the sides with provisions for joining them together as cast-in details.

Be careful with the assumption of "dead" sounding. A section of concrete pipe, when struck with a hammer, rings like a bell.

Care to go on? I'll entertain the notion.

PS: I never, ever thought I'd get to talk about concrete on THIS forum

[BassAwdyO]

How about building a small box inside of a larger box and pouring concrete in between them? Ties could be used to equally space the gap which the concrete is supposed to fill just like the ties used in concrete forms for basement walls. The smaller box would not have to be removed.

On the other hand... If you are looking for a solid enclosure, concrete is not the way to go. Bracing could do a much more effective job. If you want a super heavy enclosure or some crazy round edges maybe concrete would be worth considering

[Rafal]

Thanks everyone for your replies.

Peter, That floor horn sub is crazy. I'd like to hear that.

bg40403, Thanks for all your valuable input. you shed a lot of light on the concrete topic. This idea is still very much in conceptual stage. If I go for it, I would love to pick your brain further.

Does anyone have other ideas for non conventional enclosure building materials?

[Ninfendo]

Here are some links you might find interesting:

This is a very interesting speaker made out of concrete, although this one is a fullrange you can probably use of the ideas
http://www.speakerbuilding.com/content/1019/
http://www.speakerbuilding.com/content/1019/ferdig.jpg

A subwoofer I can recommend Stig Erik Tangens Almighty subs:
http://member.newsguy.com/~stigerik/almighty/index.html

[hilbren]

This topic has some usefull pictures: http://www.hear.nl/forums/index.php?showtopic=4813

[maiky76]

Hi!

Sorry, it's in French but it is a very interesting "how to" for concrete enclosures:
http://arolio.free.fr/albedo-beton/albb1.html
Just clic on "suite" do see the next slide.

@+
Maiky

[Music Machine]

Concrete enclosure

[Music Machine]

On the left in this picture is the mold that was designed to be destroyed to remove the concrete enclosure.

This is a 12 litre enclosure with 1 1/4" wall thickness and it weighs about 35lb. Concrete rings. As it cures (which takes years) it becomes harder and harder. The resonant frequency gets higher and higher. They are no longer in use.

Concrete might be okay for a sub, but with a larger volume and thicker walls it will be heavy. I'd stick with mdf. It's a lot more practicle, and the results aren't bad either.

Regards,
Music Machine