Joe, basically the Algonquin is an M3 modified for outdoor use, and it's often been suggested to use a bookshelf(M2,M3, even M22)as a center speaker. You didn't mention if you used it oriented vertically, which would have good dispersion to each side. If it was placed horizontally the pattern wouldn't be symmetrical.

Chess and Mo, actually it's 54.3 degrees(I used my abacus).

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Enjoy the music, not the equipment.