Need some recommendations for a replacement for the 15" speaker in my Ampeg 1540. Always loved the tone of the thing, but when I push it hard, it pops like Rerun from the tv show What's Happenin' Now? I need something that'll for sure work well with the cabinet (half the Ampeg fridge ported). I'll be driving it with a Fender 400ps which will put 145 tube watts into it so it must be 4ohms. It'll be run alongside the stock 4x10 in the top of the cab aswell. Thanks all.