Floor speaker series tannoy revolution power rating 100 watt effective output 400 watt system 25 way system principle passive frequency response 34 32000 hz sensitivity 91 dbmw noise level 88 db impedance 8 ohm crossover frequencies 250 1800 hz recommended amplifier power 25 200 power supply passive housing surface veneer speaker enclosures bass reflex removable speaker cover number of tweeters 1 treble chassis 25 mm number of midbass