Sally Army was 30 years ago, and the gear was old then. I liked their spending priorities, even then! Speaker cloth - 'how hard is it to blow through' is one way to look at it, as legitimated by Delany and Bazley's dodgy old curve fits:
https://www.math2market.com/Publicat...any-Bazley.pdf
But these days I can't be a***d - I'll hang nanna's curtains over a speaker and see what it sounds like!