Concrete is great if you feel like making something heavy on the cheap. [Marek Unger] decided to have a go, using the material to cast speaker cabinets for a home hi-fi rig (Youtube link, embedded below).
Initial attempts involved creating a laser-cut MDF outer mold, with a styrofoam core inside to be removed later. This was unsuccessful, and [Marek] developed the design further. The second revision used an inner core also made from lasercut MDF, designed to be left inside after casting. This inner mold already includes the mounting holes for the speaker drivers, making assembly easier too.
Once cast, the enclosures were fitted with Tang-Band W4-1320SIF drivers. These are a full-range driver, meaning they can be used without needing crossovers or other speakers to fill in the frequency range. Each cabinet weighs just over 10kg, and they’re ported for extra response in the lower frequency bands. Sound tests are impressive, and the rough-finished aesthetic of the final product looks great in [Marek]’s living room.