@pete_mac
in almost all crossover-based dual speaker systems I have listened to or used, the speaker's
internal crossover is not replaced or bypassed. it is still needed because the crossover
arbitrarily sets the external cross over frequency and the high-side speaker doesn't
see frequencies above this even though it can potentially handle frequencies below
this externally-set filtered signal. similarly, the bass speaker can certainly handle the
highs but doesn't for the same reason.
HP of TAS, when he built the QRS/1D took two full-range speakers, added a crossover,
sent highs to one and the lows to the other. I do not recall whether he eliminated the
crossovers.
crossovers do not, as a rule, simply set a frequency whether they are in speakers or
as an active device. they can tailor the sound.
see the 11ohm and the 15om versions of the LS3/5a for why they are so complicated
in their crossover designs.
in the picture of the KEF 105, the internal portions of the respective crossover sections
are not bypassed, they are intact, and in place and signals are still processed by
the internal sections of the crossover.
I will admit that I did look at speakers that had the capacity for really full range
like the original Ohm F and perhaps, current designs in OB that may or may not
have crossovers.