I was told that birch/maple ply (used by FMIC) is only available in Australia by import, so I used some marine grade 12-ply (practically no 'knots or fills') from my local timber yard. I had only intended to make one cab, but a sheet of ply (2400x1200mm) was big enough to make two. Baffles and backs are the same material.
The frames are just pine.
Whilst my cabs are closed-backed (and the speakers front-mounted), the speaker in my amp sounds punchier atm despite being in an open-backed cabinet. I did see a video on YouTube which suggested new speakers need to be broken in, so that might explain it. But I do love the sound and rumble of all three speakers played together (at 4Ohms) and, being as I love the sound for which Sunns have most recently been famous, I am pretty close to the sound I was looking for.
