I have a pair of PA speaker cabs with no speakers. They require 18" speakers, but I have a pair of 15" Eminence speakers handy. My question is, if I were to mod the cabs to hold a 15" speaker, would the sound be changed in a drastic manner? The cabs may have been built to make the 18"s sound good, would that design alter the sound of my 15"s to a point where it's not worth the trouble of the mod? I'm hoping to sell the Pas, so I want the sound to be the best possible. Thanks guys, rock on.

Current Gear:
Gibson Boneyard with Bigsby
Gibson 93' Explorer W/Nailbombs
G&L 93' Legacy W/Noiseless
Gibson 95' Doublecut W/Angus Bridge

Mesa Stiletto Trident
Bogner Shiva
Mesa 2x12 & 4x12 Cabs