Curious if ≈ 50 Hz would be too high for the Sub frequency given that the Carbon 7’s are 3db down at 38Hz
Would too high of a sub crossover interfere constructively with the mains and all of a sudden it’s way too bassy?
the spec is +/- 3db so you can count on the bass cutoff to be -6 db from the level of bulk of the low treble and midrange ... thus start at 50 hz for the xo and adjust... the speaker is probably down 3 db closer to 50 hz -- incidentally, the good thing about rel subs as that both the xo frequency as well as level dials have detents, so you can track where you are in its range and adjust by small step
fritz is on this board frequently he may also chime in