Bookshelf speaker series wharfedale diamond 200 power rating 75 watt system 2 way system principle passive frequency response 68 20000 hz impedance 8 ohm crossover frequency 2300 hz recommended amplifier power 15 75 capacity 32 litres power supply passive colour brown front colour black cabinet surface walnut speaker enclosure bass reflex treble chassis 25 mm bass chassis 100 mm speaker terminals screw terminal width 143 mm height 2