Adrian,
The B&C DCX354 spec sheet lists the FB354 passive crossover as "also available", so it probably will be soon ;^).
As Peter mentioned in post #878, the high output of the horn loaded 2x12" and the low crossover of around 700/650Hz for the PM90/60 with a relatively small HF horn with limited low frequency loading demands a lot from the mid driver.
Although the DCX354 has "nearly the same output" in the upper range as the DCX464, there is no replacement for displacement, smaller diaphragms simply can't put out as much SPL before running out of excursion at the lower end of their pass bands. The DCX464 is rated for another 1/3 octave lower output than the DCX354.
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The reduction in diaphragm area between the 100mm of the DCX464 vs the DCX354 76mm voice coil is apparent in the above comparison.
Art
