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Custom Concrete Speaker Cabinets
Custom Concrete Speaker Cabinets
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Old 17th June 2017, 07:30 PM   #21
CharlieLaub is online now CharlieLaub  United States
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Custom Concrete Speaker Cabinets
Quote:
Originally Posted by HeyBill View Post
A pure open baffle to start might prime the pump.
I don't think it would be practical to domestically ship a large enough slab to be useful as an OB. You are more or less local, Bill, so you could have something made on a custom basis and pick it up in person.

I think we are either doing a small-ish general-purpose 4-or-5-sided box that people can use in a speaker build or doing a much more ambitious project that would be designed for a specific set of drivers only, like a speaker kit.

It might be possible to make a 2-box set with one box nesting inside the other. The smaller box would be used for the midrange and tweeter, and the larger for a woofer, of a 3-way system.

Keep the suggestions coming!
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Old 18th June 2017, 05:19 AM   #22
whgeiger is offline whgeiger  United States
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Make slabs from lightweight concrete for the boxes. Pearlite is a possible filler candidate.
These may be joined to form an air tight seal using current adhesive and cast in-place pocket screw insert technologies. Celebrate the joints with kerfs.
For egg-shapes, of course, cast as one piece.
Dip concrete in polyurethane bath to finish to a hard, impermeable surface.
Note: Tarrasa must be ground to a finished surface before dipping/coating/sealing.
For the baffle panel(s), form from a reinforced thermo-plastic that may be CNC to specification for driver mounting. Press in flange nuts after machining.

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WHG
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Old 18th June 2017, 05:39 AM   #23
picowallspeaker is offline picowallspeaker  Italy
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This is the wrong forum. It should be moved in Design & Build section.
There is no useful piece of information about speaker systems...actually there are some obscure points like: concrete box and wooden baffle ?! And....A box in a box !?!
Are these guidelines or...?
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Old 18th June 2017, 05:39 AM   #24
Jerms is offline Jerms  United Kingdom
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An example on youtube, (bendy concrete coffee table).
https://www.youtube.com/watch?v=5HbsmFgdz0g

Making a U shape by laying up a laminate of materials and then forming should be possible. My main thought for this is to allow surface detail to be laid out sparsely, first, then fibre reinforced concrete poured... Alternatively, thin concrete or cement, then impress the stones, then add fibre concrete, then form. Would required aggressive polishing to to reveal the finish.
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Old 18th June 2017, 08:16 AM   #25
Boden is offline Boden  Netherlands
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These guys are producing Terazzo loudspeaker enclosures for some 30 years now.

https://www.taf-oss.nl

As I understand it, the internal cavities are made by polystyrene fillers/cut-to-shape- blocks, that are melted away once the walls have hardened.

It should not to be too hard to do it yourself.

Transportation costs for make on demand will be a deal breaker, I suppose.

Good luck,

Eelco
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Old 18th June 2017, 03:09 PM   #26
CharlieLaub is online now CharlieLaub  United States
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Custom Concrete Speaker Cabinets
Thanks guys, but I am NOT looking for info on HOW to make the concrete enclosures, tips about mold making, or what material to use. There is already an expert terrazzo concrete guy who will handle that. I also know that we are not the first people on the planet to use this material for speakers...

I AM simply looking for input on the SHAPE and SIZE of whatever is made.

Should it be a small, conventional general-purpose BOX with removable front and possibly rear baffles that the user would then supply when they build it up for their own project?

-or-

Should it be something that is not easy to make by the DIYer like a spherical enclosure for a midrange and tweeter that would sit on top of another cabinet, possibly part of a kit (driver choices fixed and crossover already developed)?

-or-

Some other shape or sized enclosure like an open baffle, U-/M-frame, and that kind of thing?
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Old 18th June 2017, 05:24 PM   #27
Boden is offline Boden  Netherlands
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Spherical with waveguide for the tweeter, e.g. prepared for an XT 25 without faceplate.
The design should be nightmare to make for the average diy-loudspeaker guy. Otherwise the added value is virtually zero.
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Old 18th June 2017, 05:46 PM   #28
diyaudnut is offline diyaudnut  United States
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I agree, low diffraction enclosures for upper mids, tweeter, MT coax, enclosures with tweeter waveguides. Special Horns. These are hard to DIY without molding,casting etc.

Woofer enclosures are relatively doable.
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Old 18th June 2017, 05:51 PM   #29
myhrrhleine is offline myhrrhleine  Belize
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a major consideration is the wall thickness. This will be significant for shipping and wait considerations. What is needed for wall thickness vs performance.
Also, if it is just for MR and tweeter, is concrete really needed?
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Old 18th June 2017, 06:34 PM   #30
CharlieLaub is online now CharlieLaub  United States
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Custom Concrete Speaker Cabinets
Quote:
Originally Posted by Boden View Post
Spherical with waveguide for the tweeter, e.g. prepared for an XT 25 without faceplate.
The design should be nightmare to make for the average diy-loudspeaker guy. Otherwise the added value is virtually zero.
I can envision a spherical midwoofer+tweeter enclosure. I would probably go with a 5" or 6" midwoofer and the standard 4" diameter tweeter flange, placed as close together as possible. In that way it can be used with a wide variety of MW and T drivers, including some waveguided tweeters. The idea of casting in a small waveguide is a good one, too.

To accommodate the larger sphere size, it could be supplied as two halves that are then joined together or can be assembled/disassembled repeatedly. If the two haves are nested, it would reduce the shipping size to just over half the size of the sphere.

I think that a sphere would have some nice acoustic properties (smooth baffle step transition). How to integrate that with a bass unit would take some thinking. I did have the idea that a sphere could be put above a large rectangular pedestal/box with a large (e.g. 15" or 18") driver firing upwards and the sphere almost nestled into it. If you keep below the frequency where you start to get interference between driver and sphere this might work well. Thoughts?
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