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On the highest resonance/weight saving front, I am making all the main (external) panels on my PM90s using a honeycomb core. 4mm birch ply either side of 16mm Nidaplast - considerably stiffer, lighter, and better damped than 15mm solid but considerably more expensive and time-consuming. I will stick with solid ply for the central enclosure for simplicity of manufacture. It's a nice engineering project though...The braces (possibly also of sandwich construction) and central enclosure pieces will be rebated right through the inner skin and core to the inside of the outer skin, making a usefully stiffer connection than a shallow rebate in a solid panel. Further, it's overall reduced mass results in lower stored energy; a good thing. It makes the overall dimensions slightly larger, but allows for a nicely radiused or moulded front edge to the enclosure. .
On the highest resonance/weight saving front, I am making all the main (external) panels on my PM90s using a honeycomb core. 4mm birch ply either side of 16mm Nidaplast - considerably stiffer, lighter, and better damped than 15mm solid but considerably more expensive and time-consuming. I will stick with solid ply for the central enclosure for simplicity of manufacture. It's a nice engineering project though...
The braces (possibly also of sandwich construction) and central enclosure pieces will be rebated right through the inner skin and core to the inside of the outer skin, making a usefully stiffer connection than a shallow rebate in a solid panel. Further, it's overall reduced mass results in lower stored energy; a good thing. It makes the overall dimensions slightly larger, but allows for a nicely radiused or moulded front edge to the enclosure. .
