Not being sure what specific info you'd like, here are random thoughts fm using such configs, commercial and diy**
Generally speaking: F-Response and energy and power response are better than their fully passive counterparts (OK, design permitting of course).
*1st: as you note, I too refer to BASS frequencies -- not low/sub bass -- see below, "caution".
*Having variable phase control is a useful feature.
*No issue "marrying" the top & bottom amps' amplitude or coexistence;
Caution: There IS an issue marrying sensitivity b/ween the two parts and more importantly, linearising the spl downward (in frequency) -- which in turn means yr woofs' excursion can hit the roof (or the opposite wall as it were). Say you cross @~80-90 Hz (a nice setting) you'll be hitting overwhelming energy at xover and whispering two octaves later. Woofs with high nominal sensitivity )at least) are necessary; OTOH, will you critically damp or underdamp?? to get those 20Hz at say -6dB...etc. I'm sure yuo know this better than me.
However this is tricky and none of the commercial spkrs I've used are very easy to dial in (example, Gen uses servo).
Apart from the above little detail one has to address & the fact that you have to dial in an extra active channel per side when gauging the distance between the two speakers in room placement (the midbass -- i.e. the crossing b/ween top & bottom part -- is difficult to get right so as to achieve the stereo image AND energy), things are OK.
Is there s/thing else you might be interested in (& I might know:))?
**I have used Genesis models (particularly the Vs & 301) and A-P Medea (the model with Manger drivers). The AP had an integrated amp on each side while the Gens had it separate. The Gen Vs' woofs are in same polarity front & back. The others had side firing woofs (same polarity).
I have also lived with diy, Lowther top & separately amplified bass (2-way) where, again, the FR units were sitting on top of the bass.
Generally speaking: F-Response and energy and power response are better than their fully passive counterparts (OK, design permitting of course).
*1st: as you note, I too refer to BASS frequencies -- not low/sub bass -- see below, "caution".
*Having variable phase control is a useful feature.
*No issue "marrying" the top & bottom amps' amplitude or coexistence;
Caution: There IS an issue marrying sensitivity b/ween the two parts and more importantly, linearising the spl downward (in frequency) -- which in turn means yr woofs' excursion can hit the roof (or the opposite wall as it were). Say you cross @~80-90 Hz (a nice setting) you'll be hitting overwhelming energy at xover and whispering two octaves later. Woofs with high nominal sensitivity )at least) are necessary; OTOH, will you critically damp or underdamp?? to get those 20Hz at say -6dB...etc. I'm sure yuo know this better than me.
However this is tricky and none of the commercial spkrs I've used are very easy to dial in (example, Gen uses servo).
Apart from the above little detail one has to address & the fact that you have to dial in an extra active channel per side when gauging the distance between the two speakers in room placement (the midbass -- i.e. the crossing b/ween top & bottom part -- is difficult to get right so as to achieve the stereo image AND energy), things are OK.
Is there s/thing else you might be interested in (& I might know:))?
**I have used Genesis models (particularly the Vs & 301) and A-P Medea (the model with Manger drivers). The AP had an integrated amp on each side while the Gens had it separate. The Gen Vs' woofs are in same polarity front & back. The others had side firing woofs (same polarity).
I have also lived with diy, Lowther top & separately amplified bass (2-way) where, again, the FR units were sitting on top of the bass.