Description
The PX4 is a super-power output valve for powerful receivers, capable of driving moving coil and large speakers at full volume.
Type PX4 is a directly heated power triode for the output stage of receivers and amplifiers where a considerable undistorted power output is required with an anode voltage up to 300. For this purpose the PX4 valve has exceptionally good characteristics and is particularly suitable for operating moving coil speakers at large volume without distortion.
The filament of the PX4 is of the robust oxide coated type and may be heated from A.C. through a suitable step-down transformer
Filament Voltage 4
Filament Current 1.0 amp
Anode Voltage 300
Grid Voltage -42
Anode Current Average 50mA
AudioMagical tries to cover all PX4 type made from the beginning of 1929 up to the 1960s.
Holy Grail of audio valves! The early Osram PX4 balloon shaped with slanted plate at 45 is among the best valve ever made by the Marconi Osram works.
Here we have a pair early 1930s balloon shaped.
Blue and black on glass.
Excellent sounding valves with full cup getter.
Both Osram PX4 balloon have been tested with AVO 163 at:
Osram PX4 balloon {1}: 52mA 100% emission
Osram PX4 balloon {2}: 53mA 100% emission
Supplied with provisional boxes.
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