The original
XP-66 was introduced late in the 1968 model year and continued through 1969. Significantly heavier than later versions, much of the weight difference was in the driver magnets (5 lb woofer/2 lb mid). The woofers used butyl-impregnated half-roll surrounds. Advertised specs: 30 to 19,000 Hz.; 8 ohms; 14" x 24½" x 12" deep; 40 lbs. The grill appears to be cloth.
The
XP-66B came out in 1970 and ran through the 1971 model year. Its MSRP was $109.95 with the standard cloth grill. It was also available with a fretwork lattice grill as model
XP-66K. The magnets were much lighter than on its predecessor (2 lb woofer/1½ lb mid). Advertised specs: 32-20,000 Hz; 8 ohms; 13 ⁹⁄₁₆" x 24½" x 12" deep; 33 lbs.
The
XP-66C debuted in 1972 and ran at least through 1973, perhaps longer. Its MSRP was $129.95 and was only available with the latticework grill. Weighing the same as the "B" version, the "C", nevertheless, had magnets almost as beefy as the original (4½ lb woofer/1½ lb mid). Its advertised specs were: 32-20,000 Hz; 8 ohms; 13 ⁹⁄₁₆ x 24 ¹⁄₈" x 12" deep; 33 lbs.
I have even seen a few adds from late 1976 (prob. model year 1977) for Fisher
XP-66KC speakers. These had "distinctive" lattice fretwork grills but only 10" woofers. Almost certainly Sanyo-era, they would probably not be fighting in the same weight class as the former XP-series.
(Having compiled a fairly complete chronology of Fisher's speaker offerings 1960-1973 including spec sheets, price listings, photos and illustrations; I wonder if there is enough interest in to warrant a dedicated Fisher Speakers thread. What say you?)
***I don't believe it is widely known that, prior to the Emerson buy-out, Fisher subcontracted its component speaker production to United Speaker Systems, Inc. of East Orange, NJ. United's founder, Bill Hecht (who very recently passed away -
http://www.stereophile.com/content/loudspeaker-pioneer-bill-hecht-passes-89), went on to become a huge OEM supplier for many well-known audio companies. More recently he founded Phase Technology Corp. with his son, Ken. I had a brief email correspondence with Ken about United. He agreed to ask his father about the early days with Avery Fisher. Unfortunately, I never heard back from him.***
I think Fisher's XP series speakers - most of which were really produced by United Speaker Systems, Inc. - would be much more sought after if collectors knew the history behind them:
http://www.unitedspeaker.com/