51 speaker system series bose acoustimass colour black transmission mode cable number of speakers 6 components 4x satellite 1x centre 1x subwoofer 2x surround 2x front impedance 4 8 ohm front speaker build type satellite speaker front speaker type wall mountable dimensions front wxhxd 83 2 x 189 5 x 84 9 mm front weight 1 kg central speaker type wall mountable dimensions centre wxhxd 186 8 x 87 x 81 mm centre weight 1 kg surround speaker types