The Definitive Concrete Speakers Thread. - diyAudio
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Old 26th January 2007, 07:00 AM   #1
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Location: Wisconsin....what did you expect?
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Default The Definitive Concrete Speakers Thread.

Well, I think I found a solution to my lack of woodworking ability.

http://www.io.com/~dylan/speakers/

Germans build concrete cast 5.1 speaker set

I'm working on some 2-ways based around some cheap Peerless India drivers I bought off eBay. While I've found some local audio boffins who can help me with design, I think this is a solution to building multiple pairs of speakers quickly and easily - I'm already pretty good at lost-wax casting with metal, and this is not all that different.

There are, however, a few issues with concrete, it appears.

1. Reflections. Concrete reflects really, really well. Even the tweeter vent can reflect a bit, or so I've heard.

2. Actual construction. I have'nt done much with concrete before.

3. Weight and strength. 150 lbs. is the maximum I can possibly carry, and is hence the maximum weight I can allow for these speakers.

To solve the problem of reflections, I'm thinking of rounding the back of the speaker in a similar fashion to the Insignia B-2111s. The mould would be a bit tricky to make, but the reduction in resonance ( almost no parallel surfaces) would be worth it.

Alternately, I could go with deflex panel and flat backs. This would make construction much easier. However, I don't know anything at all about deflex, so you'll have to enlighten me.

Any thoughts?
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Old 26th January 2007, 09:57 AM   #2
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Join Date: May 2004
Location: Hertfordshire
An old project using concrete pipe might get used again here:
http://www.hifiloudspeakers.info/spe...8492f64b4e9315
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Old 26th January 2007, 12:06 PM   #3
AMV8 is offline AMV8  United Kingdom
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Join Date: Jan 2005
Location: near london
Hi

I have also made concrete speakers.

I made a mid and tweeter box that fitted on top of a base unit. The mid treble box was a pyramid with the top of the pyramid leaning forward to keep the speaker faces in the right plane. The base unit was a rectangle with the base being deeper from the front to back than the top. I made both as sealed boxes.

The mid range is a directly connected to the amplifier with a single phase filter on each of the treble and base units.

I also used a plastiser in the concrete. However you do need to add sufficient cement and water to achieve a chemical mix. If you skimp on the cement or water you will have a brittle mix regardless of adding plastiser. I used steel mesh reinforcement espescially in the mid / treble box to aviod resonance in the mid range - where I find it most critical.

This is the second time that I have built concrete speakers and I have enjoyed both lots. ( The last ones were so heavy that I sold them with my last house! )

Don
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