Centre speaker series jbl studio system 25 way system principle passive frequency response 60 22000 hz sensitivity 88 dbmw impedance 8 ohm recommended amplifier power 20 125 power supply passive colour black front colour black speaker enclosures magnetically shielded removable speaker cover bass reflex number of tweeters 1 treble chassis 25 mm number of midbass drivers 2 bassmidtone chassis 100 mm bass reflex port position rear firing po