Both the high and low pass filters are set at about 325hz.
The crossover point is at F6. Meaning the high pass and low pass filters must both be at -6dB at the desired crossover frequency.
That's 6 decibels below the flat part of the curve outside the filter band. If they cross at -6dB (in phase) then they will sum together with flat frequency response. So you need to make both filters' -6dB point be at whatever crossover frequency you want.
Example: if the flat part of the voxative FR curve is at 65dB, then the -6dB point will be at 59dB. So you adjust the the high pass cross point adjustment until the 59dB part of the voxative curve is at the crossover frequency you desire.
The crossover frequency does NOT start where the curve starts to roll off. It is where the cirve is already rolling off by 6 decibels. +6 decibels is twice as loud and -6dB is twice as soft. So when they add together they will be the same volume as each of the drivers playin alone in their own spaces above and below the XO. Through the crossover one is getting louder while the other is getting softer, but at all frequencies in the XO band they must sum to make a flat FR, @ same SPL as outside the XO band.
