5U4GB Tungsol used/good 1960 some white oxide flakes inside tube flaked off filament wires

51/40

60/40

Tested on TV-7D/U

Recommended for

- SET amps
- Wright Sound SET
- Audio Note P4 Balanced mono amps
- Dared MCP7 preamp with phono
- Singlepower
- Modwright Transporter
- Donald North Audio