Bluetooth speaker portable speaker series harman kardon onyx power rating 60 watt system 25 way system speaker system 20 stereo principle active frequency response 50 22000 hz noise level 80 db impedance 4 ohm amplifier type digital power supplies rechargeable battery mains operation battery life 5 h type of battery lithium ion battery capacity 2 600 mah charging port micro usb colour white housing material plastic enclosure functions str