I can remember touring the factory in the early seventies and my tour guide pointed out a pallet of Russian plywood. He said it was used on inner linings on the corner horns and the La Scala’s. It was basically 1/2 inch but twice as strong as American 3/4 inch but it was acoustically superior because the surface was more consistent!
(Thanks Jim Parker)
Oh I’m a proud owner of a pair of almost 50 year old La Scala’s !