I recently picked up a PH412 (from anither TB'er as it so happens) and i am curious about how the crossover works on these cabs. does the switch on the back (3k, 4k, 5k) determine at which point the signal is split off to the tweeter? and if so why dont i hear a difference with the tweeter at min? i would expect that the tone coming from the speakers would also change depending on where the switch is set. for example crossover at 5k would result in more highs coming through the speakers than when it is set at 3k.