do you
really want an 18" for bass guitar? those days are kinda over (unless you're doing it right, with a crossed-over rig using 10s or 6s or whatever for mids and highs).
anyway, an eminence sigma pro18a makes for a strong, efficient and not too pricey speaker for vented boxes, assuming the specs are right. (+1 to getting the box specs and seeing what actually works there)
frankly, a blown 18" bass guitar cab is worth basically nothing; hell, i'd pay
you $10 to haul one off of my porch
