PX4 Marconi balloon made in 1930s HOLY GRAIL! slanted 45 degrees plate AC044 PP3/250 equivalent

1930s Magic Marconi balloon PX4 purple logo £ 2500 quartet


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!

This time we have a magic quartet of PX4 Marconi early type balloon shaped!

The PX4 balloon shaped with slanted plate are among the best valve ever made by the Marconi Osram works.

Here we have a matched quartet balloon shaped.

Purple Marconi decal on glass.

Excellent sounding valves with full cup getter.

All four Marconi purple logo PX4 balloon have been tested with AVO 163 at:

PX4  balloon {1}: 51mA 100% emission

PX4 balloon {2}: 49mA 100% emission

PX4  balloon {3}: 53mA 100% emission

PX4 balloon {4}: 50mA 100% emission

Supplied with provisional boxes.


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