Series
A method of connecting multiple electrical components such that there is the same current through each. In loudspeakers, connecting woofers in series is accomplished by connecting the woofers "positive to negative." Putting two woofers in series will double the system impedance and system radiating area. The net result of using two woofers in series is no gain in efficiency. However, the increase in surface area will reduce the amount of excursion required to produce a given SPL, and a higher overall SPL can be produced.