I got a YBA-4 a while back that could use some refinement. It's already been recapped and tuned up, but I think the speaker in it leaves quite a bit to be desired. Long story short, I'd appreciate some suggestions for a 15" replacement speaker that could work well in the amp for guitar, but also for bass duties. The amp gets used in my studio, more for bass than guitar at the moment, but that could always change. Is there something that would work well in both capacities? The speaker in there now just sounds sad with bass and feels like it's going to come apart at any second. Any ideas greatly appreciated!