I've seen numerous references here to 'charged coupled' crossovers. When I first saw this, I was thinking "huh, CCD based delay lines or something?" but I've since seen a couple of schematics, indicating they are really just DC biased capacitors.
I've read various threads like... http://www.audioheritage.org/vbullet...hread.php?t=43
Frankly, with my somewhat naive understanding of analog electronics and filter networks, I don't get it, and would love to see some discussion of the theory behind why it works. URLs to reading material are fine, too.