EBC91 Röhre = 6AV6 Duodiode-Triode B7G

EBC91 / 6AV6 budget triode with ECC83-style characteristics

The EBC91 combines two signal diodes and one high-gain triode on a compact B7G base. Its triode section has an amplification factor of 100, transconductance of 1.6 mA/V and plate resistance of approximately 62.5 kΩ, closely matching the usual characteristics of one ECC83 or 12AX7 section.

This makes the EBC91 attractive for value-focused preamps, guitar amplifiers, line stages and experimental audio circuits. Its additional diodes may remain unused or be incorporated into detector, level-sensing and control circuits.

Suitable applications

• Affordable audio and guitar-amplifier preamps
• High-gain stages with ECC83-style characteristics
• Line, detector and level-control circuits
• Stereo projects using optionally selected valves

Technical specifications

Valve construction

Two diodes and one high-gain triode with a common cathode

Equivalent designations

6AV6, 6BC32 and CV2526

Base

Miniature B7G, 7-pin

Heater

6.3 V at 300 mA

Typical triode condition

Va 250 V, Vg −2 V and Ia 1.2 mA

Amplification factor

µ 100

Transconductance

1.6 mA/V

Plate resistance

Approximately 62.5 kΩ

Dimensions

Approximately 18 mm in diameter and 48 mm body height excluding pins

B7G connections – bottom view

Pin 1

Triode control grid

Pin 2

Common cathode

Pins 3 and 4

Heater

Pin 5

Second diode anode

Pin 6

First diode anode

Pin 7

Triode anode

Audio design notes

One ECC83 gain-stage circuit can provide a useful starting point, but the EBC91 requires its own B7G socket, heater provision and diode-pin treatment. Two EBC91 valves draw 600 mA at 6.3 V, twice the heater current of one ECC83 operated at 6.3 V.

Safety notice: Tube preamplifiers may contain lethal anode voltages and should only be constructed and tested by suitably skilled users.

Questions about selection and audio use

Is the EBC91 a useful low-cost substitute for half an ECC83?

Yes, its triode section provides µ 100, 1.6 mA/V transconductance and approximately 62.5 kΩ plate resistance. It is an attractive alternative in a new DIY design, although it needs a B7G socket and a separately planned heater supply.

Can the EBC91 be used in a guitar or hi-fi preamplifier?

Yes, it is suitable for voltage gain, input stages and gain-shaping guitar-amplifier circuits. The plate resistor, cathode bias and coupling network may be developed from familiar ECC83 practice and adjusted for the chosen operating point.

Can the EBC91 diodes provide useful functions in an audio project?

Yes, they can be used for signal detection, rectification, level indication or simple limiting and control circuits. When they are not required, their unused connections should still be handled deliberately in the circuit layout.