Outdoor speaker bookshelf speaker system 2 way system speaker system 20 stereo principle active frequency response 90 20000 hz sensitivity 87 dbmw impedance 8 ohm crossover frequency 2300 hz recommended amplifier power 20 100 colour black front colour black housing surface rubber design front firing subwoofer speaker enclosure magnetically shielded number of tweeters 1 treble chassis 25 mm tweeter material tweeter cmmd lite calotte numb