(!!!!) (Single) 5691 RCA branded GE red base black plates NOS 1960's a few vertical scratches on base (2.1ma/2.3ma)1 low noise tube) 5691 RCA branded GE red base black plates NOS 1960's a few vertical scratches on base smeared printing on glass 1 section) 2. 1ma Gm=1500 1 section) 2. 3ma Gm=1600 best 6SL7GT sub very smooth sound low noise good midrange detail NOS Ma Range = 2 3ma NOS Gm = 1500 1600 Recommended for Ampeg Heritage B 15 Alessandro Itallian Greyhound jazz amp Alessandro Black and Tan 2005 Almarro A318B Eddie Current