Pa sound system principle active power 800 watt woofer size 10 inch design 2 way system construction bi amping speaker lf 1x 10 dimensions 245 x 360 x 580 mm weight 15 kg noise level 125 db impedance 8 ohm frequency response 40 20000 hz connections microphone sd card usb types of connection clamp contacts usb rcacinch stereo case material bass reflex