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The thing about speakers, of course, is that there’s not really any good way, that I can think of, to convey their most important functional quality online:  How do they sound?

Still, these prototypes from industrial designer Shmuel Linski look so good I couldn’t pass ‘em up. Snip:

The horn speaker technology that I used in my project, works just great with the concrete, even without the need of padding the speakers from the inside. The driver, which is located in the top part of the speaker, moves the air through a pipe (96cm long) and into a horn-shaped mouth in the bottom of the speaker. The weight (56kg) makes the speakers very solid.

Exposed, as he calls the set, was a capstone project for Linkski’s course of studies at Israel’s Shenkar College of Engineering and Design. There’s not much by way of explanation, but his press kit includes a series of photos that demonstrate the casting process, which I’ve annotated below…

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The key missing detail is the inner mold geometry that creates the horn and speaker- and panel-mounting recesses. I think it has to be a sacrificial form, of some sort, that gets chipped, dissolved, burned and/or melted out after the concrete has hardened. Polystyrene foam, maybe?

linski design

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.


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Comments

  1. David says:

    it looks like he’s molding both sides separately and then bonding them together after they dry.

    1. Sean Ragan says:

      I thought so too, at first, but I if you look closely at the cast speakers there’s no mold line at all, that I can see. Maybe it’s easier to hide the joint than I imagine.

  2. Dave Bell says:

    “… then why the rubber gloves?”
    Haven’t worked with concrete much, have you?

    1. Sean Ragan says:

      Who cares? If you have something helpful to add, please feel free. But why spend the time and energy commenting if you’re just going to be snide?

  3. David says:

    I think you’re right about it not being a two-piece, the photos showing the wiring panel and central rub definitely don’t have mould lines. It could be a sacrificial plug, but possibly not something burned out, since you probably don’t want to put the concrete into a oven and risk the moisture loss causing cracking, plus there don’t seem to be any signs of residue (although that could just be through cleaning). I’m thinking more a two piece flexible plug, the lower part forms the inside of the lower horn and pipe, the upper plug part forms the inside of the upper horn. Then you can drag them out once the concrete is cured. I actually like your idea of a dissolving plug, that seems like a great idea and well suited to this kind of form. Any chance you can contact the maker and ask him?

  4. Perhaps it’s not sacrificial at all? Maybe there’s two cones attached to a central pipe. The cones are removed to leave the concrete cone and the central pipe stays.

    1. miroslava von schlochbaum says:

      That’s so ingenious it should’ve been obvious (but wasn’t to me). …and the cone ends twist into the pipe to keep it in the middle of the mold. (now watch, if we ever hear back, that’ll be not how it’s actually done)