I have got this huge, heavy, Frudua bass guitar speaker to fix. A friend of my son almost threw it away, right before I salvaged it. The passive circuit was ok, all drivers as well, all it took was some re-shaping of the internal wiring. Not really sure it works on a stage, will need some testing in real conditions. It’s a Frudua Stage 312 Sub-Fi, very aged but very solid. Serious work that you won’t find in current models.

Frudua Stage 312 Sub-Fi