The Rhombus sub

This project is pretty straightforward except for the enclosure shape. It is a passive 4 cubic foot sealed enclosure loaded with a down firing Dayton Ultimax 15. Power is provided by a bridged Crown XLS1002. I've built many subs over the years and listened to far more and am very pleased with the Ultimax 15 for both music and home theater. My main speakers (Campbell/Holtz Bourdeaux kit) are capable of excellent bass themselves and after much tweaking I settled on a low pass to this sub of 50 hz with a 12 dB slope.

I originally settled on the shape as a joke to myself in that my carpentry skills are unable to produce anything with square joints :p At the same time I believed the shape would provide visual interest. The enclosure is of 3/4" MDF and sits on furniture legs sourced from Amazon and bolted to the recessed downward facing baffle.

I realized as I began construction that due to the shape of the enclosure and the viewing angle from the listening position it would appear visually smaller than it actually is. This illusion is due to the fact that the front face of the enclosure is not orthogonal to the line of sight from the listening position; it's receding plane fooling the eye.

Test fit of driver. Baffle will face the floor when installed with furniture legs bolting into the corners of the recessed baffle. Two horizontal window braces already installed and additional vertical bracing is being added between the baffle, window braces and top.
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Another interior view before all sides are attached. Short vertical braces installed at each of the woofer screw hole locations reinforce the baffle by spreading loads into the window braces and cabinet sides. Inside of cabinet top (bottom in this view) will have an X shaped brace installed for reinforcement.
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Initial "does it work" test. I ended up shortening the legs considerably as I found these too tall. Spring type binding posts can be seen as well.
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Enclosure is veneered with paper backed mahogany using contact cement; my preferred method.
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Experimented with a somewhat distressed finished on this project. I liked it.
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The forced perspective in photographs usually disguises how slanted the front and back sides really are. This view shows true shape to good effect.
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Final placement in the living room/theater/listening room.
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