Germans build concrete cast 5.1 speaker set

Nordic · 24th January 2007, 05:42 AM

Thought you may enjoy this one...

Concrete and wax molds used to make small speakers and sub... Good training wheels for bigger projects.

http://propirate.net/betonboxen/

Spasticteapot · 24th January 2007, 05:58 AM

Very nice!

I was thinking of making a transmission-line speaker, and while ridiculously heavy, concrete does have the definite advantage of being non-resonant.

weissi · 24th January 2007, 06:06 AM

Not Germans - Tyroleans

Although some of them were born Germans....

Spasticteapot · 24th January 2007, 06:18 AM

This could be done much, much more easily with "blucor" insulation foam and a hot-wire cutter. Just melt it out with acetone or gasoline, and you're done.

I wonder what the density of concrete is?

Nordic · 24th January 2007, 09:10 AM

They are designed to hit you like a brick...

You got to love them for thinking the whole project through, getting all the materials BEFORE THE TIME, giving it a professional finish etc... I guess a melted layer of wax works good as dampening material...

Hezz · 24th January 2007, 03:44 PM

A good way to build some high end cabinets. However, concrete is weak in tensile strength so the walls if that thin should be reinforced with something. Maybe random glass fibers in the mix. IF you drop it it's history.

EDIT: After looking at the pictures again I see that there is a reinforcing mesh around the slug.

Using this technique and some synthetic castable marble would yield really good results. You could also sandwich a brace in between the wax slugs and wrap it in fiberglass to make some reinforcing. The wax can be recycled by pouring it into a retangular mold.

This gives me an idea for the head unit of some three ways that I am going to build. Maybe I will go all out and make a Wilson quality top cabinet.

The unfortunate thing about concrete is that it takes 30 - 90 days for the concrete to reach full strength. But at least you would be knowing that the sound quality would increase for for a period of time.

It would be interesting to see some TL build this way. You coud use thin plastic scraps from the sign shops that are usually sold for 1 dollar a pound for the mold cavity. Then tape them together and brace them and leave one side open. Installing bolt ancors in the cement. Then you have a very good cabinet and one side removable to adjust internal dampening. Which in a TL is very important to get just right.

Cal Weldon · 24th January 2007, 04:09 PM

Quote:

Originally posted by Spasticteapot
I wonder what the density of concrete is?

Post Haste?

Quote:

Originally posted by Hezz
it takes 30 - 90 days for the concrete to reach full strength

28 days at 20C and standard inside humidity will get you there.

LaMa · 24th January 2007, 07:14 PM

The density of concrete depends on the mix, but normally it will be similar to aluminium (yes you read it correctly) about 2200 - 2600 kg/m3 for concrete, while aluminium is about 2700-2900 kg/m3

Curing of concrete never stops, at least for the first couple of years, therefore a standard measure in time, 28 days, is taken at which the prescribed strength has to be yielded.

roger_lew · 24th January 2007, 07:20 PM

That is 150 lb / cubic foot for those of us who are use to thinking in SI

http://www.google.com/search?q=2400+...to+lb%2Fft%5E3

24th January 2007, 05:42 AM	#1
Nordic diyAudio Member Join Date: Sep 2005	Germans build concrete cast 5.1 speaker set Thought you may enjoy this one... Concrete and wax molds used to make small speakers and sub... Good training wheels for bigger projects. http://propirate.net/betonboxen/

24th January 2007, 06:06 AM	#3
weissi diyAudio Member Join Date: Sep 2002 Location: Austria	Not Germans - Tyroleans Although some of them were born Germans.... __________________ regards / servus

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24th January 2007, 05:58 AM	#2
Spasticteapot diyAudio Member Join Date: Jan 2006 Location: Wisconsin....what did you expect?	Very nice! I was thinking of making a transmission-line speaker, and while ridiculously heavy, concrete does have the definite advantage of being non-resonant.

24th January 2007, 06:18 AM	#4
Spasticteapot diyAudio Member Join Date: Jan 2006 Location: Wisconsin....what did you expect?	This could be done much, much more easily with "blucor" insulation foam and a hot-wire cutter. Just melt it out with acetone or gasoline, and you're done. I wonder what the density of concrete is?

24th January 2007, 09:10 AM	#5
Nordic diyAudio Member Join Date: Sep 2005	They are designed to hit you like a brick... You got to love them for thinking the whole project through, getting all the materials BEFORE THE TIME, giving it a professional finish etc... I guess a melted layer of wax works good as dampening material...

24th January 2007, 03:44 PM	#6
Hezz diyAudio Member Join Date: Dec 2002 Location: Utah	A good way to build some high end cabinets. However, concrete is weak in tensile strength so the walls if that thin should be reinforced with something. Maybe random glass fibers in the mix. IF you drop it it's history. EDIT: After looking at the pictures again I see that there is a reinforcing mesh around the slug. Using this technique and some synthetic castable marble would yield really good results. You could also sandwich a brace in between the wax slugs and wrap it in fiberglass to make some reinforcing. The wax can be recycled by pouring it into a retangular mold. This gives me an idea for the head unit of some three ways that I am going to build. Maybe I will go all out and make a Wilson quality top cabinet. The unfortunate thing about concrete is that it takes 30 - 90 days for the concrete to reach full strength. But at least you would be knowing that the sound quality would increase for for a period of time. It would be interesting to see some TL build this way. You coud use thin plastic scraps from the sign shops that are usually sold for 1 dollar a pound for the mold cavity. Then tape them together and brace them and leave one side open. Installing bolt ancors in the cement. Then you have a very good cabinet and one side removable to adjust internal dampening. Which in a TL is very important to get just right.

24th January 2007, 07:14 PM	#8
LaMa diyAudio Member Join Date: Sep 2002 Location: NL	The density of concrete depends on the mix, but normally it will be similar to aluminium (yes you read it correctly) about 2200 - 2600 kg/m3 for concrete, while aluminium is about 2700-2900 kg/m3 Curing of concrete never stops, at least for the first couple of years, therefore a standard measure in time, 28 days, is taken at which the prescribed strength has to be yielded.

24th January 2007, 07:20 PM	#9
roger_lew diyAudio Member Join Date: Nov 2005 Location: Moscow, ID	That is 150 lb / cubic foot for those of us who are use to thinking in SI http://www.google.com/search?q=2400+...to+lb%2Fft%5E3

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