I bought another pair of pre-owned SDAs today. The owner's manual that originally came with the speakers indicated they were SDA-2A speakers, but the picture on the manual doesn't look exactly like the speakers below. The SDA driver is an MW6511, built in October 1987, the "regular" mid-driver is an MW6503 built in October 1988 and stamped "Engineered for CRS" on the back. The owner thought they were SDA-2As and sold them as such but they seem to be SDA-2Bs. So, what are these really?
The speakers had been sitting unused for a few years, but I got them cleaned up pretty well I think. And, no the cleaning did not involve the use of Armor All. ;)