dbane883

It's 6000lb concrete. For 1" thickness for these dimensions, its more than plenty with the aggregate I used. Polyfibres are useful if the spans are greater than say 18" at 1" thick. The enclosures are not load bearing anyways like a countertop might be

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Aside from watches, my other hobbies include working with various concrete mixtures to make countertops, furniture, etc as well as hifi audio. So last summer I embarked on a project that combined both of these interests and built prototype speakers with enclosures made entirely out of concrete. The problem with many traditional speaker cabinets made out of wood/mdf is "resonance". Could be good if controlled,, could be terrible if its not. Eliminating resonance is one way to get a purer sound from the drivers. I decided on a closed cabinet design using an economical tweeter/driver set from Dayton Audio. The excercise was more to see if a completely closed design could be built. The crossovers would have to fit through the woofer hole. Here is the final product: I started by drafting the cabinet form on paper, and cut out pieces of acrylic/plywood for the drivers: The form itself was made out of melamine, which is slick enough that once the concrete is set, it's easily removed: Because the final product has to be hollow, i created the hollow forms using syrofoam: I also embedded aluminum rods beside the driver knockouts. These will later be used as to secure the screws for the drivers themselves: Driver knockouts in place: Followed by the styrofoam (the rods will create the channel for the binding posts): The pour was a near disaster. Apparently securing the styrofoam with two sided tape was not ideal, since styrofoam floats!!.. I had to litterally push it down while i as pouring the concrete until it was semi-set: Once the forms are released, it's not a pretty sight: Slowly chipping away at the styrofoam interior: Test fitting the drivers..perfect: Drilled the screw holes into the aforementioned aluminum rods: http://i123.photobucket.com/albums/o309/darthbane883/Concrete%20Speakers/IMG_0157_zpsbe94834b.jpg Now the grinding/polishing: After several hours of wet polishing using diamond resin pads: Tapping and final assembly: Prototypes complete: Despite a few hiccups along the way, overall, I think the process was a success. The speakers sound incredible and on par with speakers that cost $3k-5k easily. While the process might seem a bit crude, you gotta remember, I didn't have a guide to work with. I've never really seen this done before and there is definitely room for improvement. But this was just a prototype which I'm currently using in my home office. My project this summer will be to build the ultimate home monitors using some high end Danish Scan Speak tweeters/woofers using custom-made cross overs. I think i will be using a ported design this time. Stay tuned.

ok.. just checking... congrats on fixing it. Better than a 2+ month wait for a very simple fix.

Did you place the friction washer above or below the click spring?

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