1 pair) 5998A Sylvania JAN NOS 1980 (5998A=7236) from factory case of 100

1 tube) 118/131mA Gm=15,900/16,800

1 tube) 121/130mA Gm=15,800/16,200

MATCHED ON AMPLITREX

Good mA = 100mA 

BEST FOR:
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Peter Millett headphone amp
Woo Audio 2
Woo Audio 3
Woo Audio WA3+
Darkvoice 336i
Darkvoice 336SE
Fi 421A
Singepower Extreme

(5998 is an uprated 6AS7G and has a 13 watt plate dissipation rating)
(the 5998 sounds very clear and has superb overall sonics, the 421A Western Electric sounds even better; slightly more magical sound)
(5998 Mu = 5.4, Gm = 15500, Rplate = 350 ohms, Vplate max = 250 volts and Vplate max 5998A = 275V)
(7236 Mu = 4.8, Gm = 12500, Rplate = 350 ohms, Vplate max = 300 volts)
(7236 is a computer rated 5998A, 7236 and 5998A are uprated from 5998)
(6AS7G Mu = 2, Gm = 7000, Rplate = 280 ohms)
(6080 Mu = 2, Gm = 6500-7000, Rplate = 280-300 ohms)

5998 substitute = 7236
7236 is a computer rated 5998A

5998 RATINGS:
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Filament Voltage 6.3 V
Filament Current 2.4 A
Plate Voltage (max) 250 V
Plate Current (max) 125 mA
Plate Dissipation (max) per section 13 W