(!!!) (#1 6550 Tungsol black plate single) 6550 Tungsol black plate low hours/like new 1960 (146ma)
(!!) (#1 6550 Tungsol Pair - Best Overall) 6550 Tungsol gray plate with vent holes 1965 (132ma and 138ma)
(!!) (#2 6550 TUNGSOL PAIR) 6550 Tungsol used/good 1960's (127ma and 132ma) (matched on Amplitrex)
(!!) (#3 6550 TUNGSOL PAIR) 6550 Tungsol used/good 1965 (122ma & 120ma)
(!) (#1 6550 SYLVANIA PAIR) 6550 Sylvania welded plates used/test like new 1970's (140ma and 141ma) 1% matched (strong Ma and Gm)
(!) (#2 Best 6550 Single) 6550 Tungsol smooth gray plate like new 1961 (129ma)
(!) 6550 Sylvania used/tests like new 1970's no printing (132ma)
(!) 6550 Tungsol gray plate - vent holes - used/good around 1970 (136ma)
6550 Sylvania branded RCA used/good 1977 (122ma)
6550 Sylvania used/very good 1970's (126ma)
6550 Tungsol gray plate with vent holes used/75% 1974 (90ma)
6550A GE NOS brown bottom 1978 "stapled plates" (138ma)
6550A GE used/55% 1970's "welded plates" (82ma)
