(!!!!) (Best Overall Single) ECC33 Mullard gray plates "D" getter halo NOS 1961 (9/9ma) 1-2% section balance

1 low noise tube) ECC33 Mullard (Blackburn UK factory) oval gray plates "D" getter halo NOS 1961 very good printing 1 section) 9ma Gm=4200 1 section) 9ma Gm=4300   Good mA range = 7-10mA Good Gm = 3200-3600   - Sonic Comments: "the ECC33s sound great - big, expansive and very clean and open" - Best sub for 6SN7GTB   Vfil=6.3V @ 400ma Maximum ratings: Vplate=300V, Vfil-cathode=100V Typical operation: Vplate=250V Vgrid = -4V Iplate=9ma Gm=3600 Mu=35 Rplate=9.7Kohms Rk=450 ohms   Recommended for:  - Bada PH-12 headphone amp - Eddie Current Balancing Act - deHavilland Ultraverve