Bookshelf speaker series indiana line dj power rating 30 watt effective output 160 watt system 3 way system principle passive frequency response 38 22000 hz sensitivity 94 dbmw impedances 4 6 8 ohm crossover frequencies 500 4000 hz recommended amplifier power 30 160 power supply passive colour black cabinet surface ash housing surface veneer housing material mdf enclosure speaker enclosures bass reflex magnetically shielded removable s