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(!!!!!) (Best Pair) JAN-5691 Philips by Sylvania black plates NOS 1984-1985 (2.0/2.2mA and 2.1/2.4mA) (Best 6SL7GT sub) (same internals as 5691 red base) 1-3% matched
(!!!!!) (Best Value Single) JAN-5691 Philips by Sylvania black plates NOS 1985 (2.4/2.6ma) (Best 6SL7GT sub)
(!!!!!) (Best Value Single) JAN-5691 Sylvania black plates NOS 1979 (2.1/2.1ma) (Best 6SL7GT sub)
(!!!) (Recommended Single) 5691 RCA Red Base black plates used/good 1959 (2.3/2.0ma)
5691 RCA Red Base Black Plates used 1948 (2.2/2.4ma) (Gm=62% and 75%)
