Looks like some sort of ports. No foam, but they said it is supposed to stop a standing-wave and have it so that the high, low and mid frequencies hit you at the same time rather than the highs hitting you first. Whether that’s true or not I don’t know, but it sounds great and unique. Very punchy, clear, detailed and hi-fi. With my other cabs also you can hear and feel the vibrations of the sides and back, like maybe there’s some sound leakage there, while this one seems to have none of that, giving this denser quality to the notes just all being pushed forward. It’s shorter and less wide, but deeper in dimensions. The maker is Smith Audio (his name is John Smith lol). I hope his stuff can actually make it into production. I’m glad to at least have mine
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