hi neil,
i' sure brian could explain it better than me, but i imagine it's not a simple straight crossover. probably, differing slopes on the hi-pass & low pass, & different frequencies where they kick in...
for example, a crossovers' super-tweeter high pass may be a straight 24db/octave, cross, at, say 10khz. the tweeters' low pass may be 6db/octave at, say, 8khz, then 24db/octave at 9.5khz.
it's unlikely the vmps' crossovers are anything like the above examples, but it's something like that, not just a simple 24db/octavre cross, at, for example, 200hz, as brian suggests, forbas/midrange cross...
hth,
doug s.