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Vacuum Tube Sockets: Valve Bases

Vacuum Tube Sockets: Valve Bases

Over the years there have been very many different bases or sockets used for thermionic valves / vacuum tubes.

These sockets enable the tubes to be inserted and removed very easily - very useful for times when the valves fail. It also provides a convenient method of connecting them in circuit. The sockets can be soldered rather than soldering the tubes and risking damage to them.

B4 Valve Socket
Standard nameA4A
Alternative namesBritish 4-pin, European 4 pin
Pins in base4
Pin layout16.25 mm kite
Pin diameter3.2mm
Usage dates1915 - to early 1930s
B5 Valve Socket
Standard nameO5A
Alternative namesBritish 5-pin, European 5 pin
Pins in base
Pin layout16.25mm kite; it can be explained as a B4 valve socket with a central 5th pin added
Pin diameter3.2mm
Usage dates1927 - to early 1930s
B7 Valve Socket
Standard nameM7A
Alternative namesBritish 7 pin
Pins in base7
Pin layoutOval
Pin diameter3.2mm
Usage dates1930s, but fell into disuse when Octal valve socket / base was introduced
B7G Valve Socket
Standard nameB7G
Alternative namesMiniature, button, Mi-7
Pins in base7
Pin layout9.5 mm (3/8 inch) circle. 45° between pins progressing from 1 to 7; 45° between 1 and 7.
Pin diameter1.02mm
Usage dates1939 onwards
B9A Valve Socket
Standard nameB9A
Alternative namesNoval, miniature 9-pin, Button 9 pin
Pins in base9
Pin layout11.9mm (15/32 inch) circle; 36° between pins progressing from 1 to 9; 72° between 1 and 9
Pin diameter1.02mm
Usage dates1948 onwards
Octal Valve Socket
Standard nameK8A
Alternative namesInternational Octal, A08
Pins in base8
Pin layout17.5 mm (11/16 inch) circle spaced 45°. Central spigot diameter 7.8 mm with locating profile
Pin diameter2.36 mm
Usage dates1935 onwards



Watch the video: How to Breadboard a Vacuum Tube Preamp 6SN7 - Part 1 (November 2021).