50 Radiotron UX250 National Union CX350 Cunningham CX350 DeForest Audion 50 matched quartet balloon audio valves

Description

The type 50 valve is a power amplifier valve designed for use primarily in the output stage of audio frequency amplifier employing transformer coupling.

It is capable of delivering large undistorted power.

Filament voltage 7.5

Filament current 1.25

Plate voltage 400

Grid Voltage -70

Transconductance 2100

Matched quartet of balloon type UX50 CX350 balloon valves.

The Holy Grail of audio valves

Radiotron UX250 tested 50mA 100%

National Union CX350 tested 51mA 100%

Cunningham CX350 tested 51mA 100%

DeForest Audion 50 tested 52mA 100%