When upgrading to or matching other non-JBL drivers/cabinets with JBL drivers, remember that JBL has used a negative polarity convention. A positve connection to the positive (red) speaker terminal produces cone travel that moves inward (backwrad) first. You must reverse the connection of the lead wires to the speaker(s) in order for them to be phased properly with other manufacturer's drivers. JBL is finally changing this, but only on new model introductions.