Bluetooth speaker portable speaker power rating 20 watt effective output 20 watt system 2 way system speaker system 20 stereo principle active amplifier type digital power supplies rechargeable battery mains operation colour brown controllable via remote control control feature bluetooth pairing speaker enclosure bass reflex number of tweeters 1 treble chassis 20 mm tweeter material tweeter tissue tweeter type tweeter calotte number of midbass dr