EF814

Small Signal Pentode — Noval

Telefunken

Known Equivalents & Substitutes

EF1846EJ7CV2195

Similar Tubes (Not Drop-In Compatible)

Same Noval base and similar characteristics — the EF814 is a special quality variant of the EF91 family per Brans Vademecum

Z77

British designation for the EF91 family — same Noval base and characteristics as EF814

Electrical Specifications

Section 1 — Pentode

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)250V

Screen Voltage (max)Screen Voltage (max)250V

Anode Dissipation (max)Anode Dissipation (max)2.5W

Screen Dissipation (max)Screen Dissipation (max)0.9W

Cathode Current (max)Cathode Current (max)

Section 2 — Triode Strapped

Absolute Maximum

Anode Dissipation (max)Anode Dissipation (max)2.5W

Typical Operating

Anode Voltage (typical)Anode Voltage200V

Grid 1 Bias VoltageGrid 1 Bias Voltage-2.5V

Anode CurrentAnode Current14.1mA

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.3A

Notes

The EF814 is a Telefunken designation closely related to the EF184. No standalone EF814 datasheet has been found in major tube data repositories; specifications are derived from the EF184 Philips datasheet (January 1970) and cross-referenced with TDSL data.
The EF814K variant was specially selected by David Bock for use in high-end condenser microphones, chosen for characteristics similar to the VF14.
Cathode bias resistor operation is recommended. The tube should not be used in circuits with automatic gain control to ensure good performance with respect to cross-modulation and microphony.
Pin 6 is an internal shield connected to cathode; pin 9 is the metallic envelope coating, also connected internally to cathode.

Pin Layout — Noval

1Suppressor Grid (g3,internally connected to cathode)

2Control Grid (g1)

3

References