6922EH tube E88CC EHX Röhre V1+low mic+lownoise Röhren Set

Electro-Harmonix 6922EH / E88CC – low-noise V1 set of two

This set contains two current-production Electro-Harmonix 6922EH valves. The 6922EH is an indirectly heated high-transconductance dual triode with two electrically separate systems, a nine-pin B9A Noval base and a fixed 6.3 V heater supply.

BTB selects both valves for sensitive V1, phono, line and driver positions with attention to low noise, low hum and low microphony. An optional matched / balanced grade additionally groups the valves so that all four triode systems have closely corresponding electrical values.

Suitable applications

• Phono preamplifiers whose circuits explicitly specify E88CC or 6922 valves
• DAC and CD-player output stages with a suitable operating point
• Hi-fi and studio line-level stages
• Driver, buffer and cathode-follower stages requiring relatively low plate resistance
• Differential, cascode and balanced amplifier stages
• Compatible headphone amplifiers and valve-hybrid equipment

BTB selection and options

Package contents

Two Electro-Harmonix 6922EH valves

Standard selection

Checked for low microphony, low noise and low hum in sensitive V1 and audio positions

Matched option

The two valves are grouped for closely corresponding electrical measurements

Balanced option

The two triode systems within each valve are selected for closely corresponding values

Complete selection with the option enabled

All four triode systems in the two valves are considered together

Production type

Current production, not historical NOS stock

Country of origin

Russia according to the current manufacturer information

Technical data

Valve type

Indirectly heated high-transconductance dual triode for audio-frequency voltage amplification

Type designations

6922EH and E88CC

System construction

Two electrically separate triode systems with an internal electrostatic screen

Base

Nine-pin B9A Noval

Heater voltage

6.3 V; permitted data-sheet range 6.0 to 6.6 V

Heater current

335 to 385 mA per valve

Data-sheet test point

90 V plate voltage and an 82 Ω cathode resistor with a 6.3 V heater supply

Plate current at the test point

10 to 20 mA per triode system

Transconductance at the test point

9 to 17 mA/V

Amplification factor at the test point

24 to 40

Maximum plate voltage

300 V per triode system

Maximum average cathode current

20 mA per triode system

Maximum plate dissipation

1.8 W per triode system

Maximum grid-circuit resistance

1.0 MΩ per triode system

Maximum negative grid voltage

-100 V

Maximum heater-to-cathode voltage

±150 V

Heater-to-cathode insulation-resistance test

At least 12.5 MΩ at a test voltage of ±200 V

Maximum temperature at the hottest part of the envelope

393 K, approximately 120 °C

Dimensions

Maximum approximately Ø22.5 × 56.5 mm

Pinout

Triode system on pins 1 to 3

Pin 1 plate, pin 2 control grid and pin 3 cathode

Heater connections

Pins 4 and 5; the 6922EH does not provide a 12.6 V series-heater configuration

Triode system on pins 6 to 8

Pin 6 plate, pin 7 control grid and pin 8 cathode

Pin 9

Internal electrostatic screen between the two systems

Important wiring note

Pin 9 is not a heater centre point and must not be wired like an ECC83 or ECC82

Comparison with related dual triodes

6922 and E88CC

American and European designations within the same basic quality dual-triode family

ECC88 or 6DJ8

Closely related and pin-compatible in many devices, but individual versions can have different ratings or service-life classifications

E188CC or 7308

Related quality and long-life variants with their own specifications; not automatically identical substitutes

ECC83 or 12AX7

Uses different heater wiring, substantially greater voltage gain and much lower transconductance; not a direct substitute

Sound positioning

BTB subjectively describes the 6922EH as neutral to slightly warm, with clear midrange, firm bass and fine treble. The audible result also depends on the operating point, plate load, coupling capacitors, power supply, feedback, source equipment and complete audio system.

Selection and application notes

The high transconductance makes the 6922EH sensitive to unsuitable wiring and parasitic radio-frequency oscillation. Short grid paths, suitable grid stoppers and effective power-supply decoupling are particularly important in cascode, differential and driver stages.

Pin 9 is an internal screen rather than a heater centre point. The valve must not be wired like an ECC83, ECC82 or 12AT7 with configurable 6.3 or 12.6 V heater operation.

The matched / balanced option can provide additional technical value in phono, stereo, differential and balanced driver stages. In a simple input stage, the included noise and microphony selection is often more important.

Hazardous plate voltages and stored charge may remain inside the equipment. Disconnect the mains supply, discharge the circuit properly and allow the valves to cool before replacement.

Questions about selection and use

Is the Electro-Harmonix 6922EH V1 set suitable for phono, DAC, line and driver stages?

Yes, the Electro-Harmonix 6922EH V1 set is suitable for compatible phono, DAC, line, buffer and driver stages specifying an E88CC or 6922. The heater voltage, operating point, heater-to-cathode voltage and mechanical clearance must suit the circuit.

Can the Electro-Harmonix set replace two existing E88CC, 6922 or suitable 6DJ8 valves?

Yes, the Electro-Harmonix set can replace two E88CC or 6922 valves and suitable ECC88 or 6DJ8 applications when the ratings, socket wiring and operating point match. An ECC83 or 12AX7 is not a direct substitute despite using a B9A base.

Is the matched / balanced option useful for phono, stereo and differential stages?

Yes, the matched / balanced option is useful for phono, stereo, differential and balanced driver stages because it supports closely corresponding values between both valves and across all four triode systems.