I am always interested in the oddball/fringe makers and those who are experimenting outside the norm. I happened on a Greek site which sells instruments made by Australian luthier named Richard Morgan who lives in Tasmania.
I think that this link leads to his blog.Radial Braced Pretensioned Soundboard
The uniquely designed soundboard is radial braced, with each of the divergent pieces under tension to form an S curve. If the tension was removed the pieces would return to being straight. The tension or torsion is what “enlivens” most soundboards and this is a different way of achieving it.
Some unusual features like adjustable neck and (I think) radial-braced multi-pieced top and back. The bridges look really clunky on these but the sound doesn't sound all that bad. I guess these are technically flattops.
Some videos:
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