Hi:
Took this out of the Apogee users web site. http://www.apogeespeakers.totalserve.co.uk/. Hope it helps. "Apogee also manufactured a large “LCR” monitor speakers for use as Left, Center, and Right channel speakers in a home theater system. A well built, large 40 pound monitor speakers, the Apogee LCR’s contained two 6½ inch dynamic woofers in a D'Appolito configuration around a 4 inch ribbon which was “rotatable” for use in either vertical (center) or horizontal (left or right) placement. In 1998 the speaker was re-designated Perseus.
Another home theater speaker was the Apogee Ribbon Monitor. This was a essentially an LCR without one of the 6½ inch dynamic woofers in a proportionally smaller enclosure, I believe the Hi-Fi journalist Ken Kessler uses 2 pairs of these in his home theatre setup.
The 1998 Cassiopeia speaker was essentially a re-styled Ribbon Monitor, designed to match the Cepheus series with a slanted outside edge, available in wood veneer finishes. To allow "bookshelf" use the bass port was relocated to the front of the enclosure."