EF184 Röhre = 6EJ7 Pentode Noval B9A Uf 6,3V
€5.90
Delivery time: ca. 1 - 5 days
For RF, IF, video and wideband amplifier stages in equipment
Suited to TV service, test gear, audio and spare inventory
Socket Noval B9A, 9-pin, frame-grid pentode
EF184 / 6EJ7 for active-screen audio stages
The EF184 is a high-transconductance frame-grid pentode providing 15 mA/V at a typical anode current of 10 mA. These characteristics make it attractive for wideband line amplifiers, preamplifiers and current-capable audio drivers.
The BestPentode principle published by Frank Blöhbaum may provide design inspiration. The EF184 application described here is an independent engineering idea; no type-specific circuit, test, approval or cooperation is claimed. A universal noise or distortion advantage is not guaranteed.
Suitable applications
- Actively controlled screen-grid and pentode stages
- Wideband line and studio amplifiers
- Driver stages for audio output valves
- Stereo and differential circuits using selected valves
Technical specifications
- Valve type
- Sharp-cutoff frame-grid pentode
- Equivalent designation
- 6EJ7
- Base
- Noval B9A, 9-pin
- Heater
- 6.3 V at 300 mA
- Typical operating condition
- Va 200 V, Vg2 200 V, Vg1 −2.5 V, Ia 10 mA and Ig2 4.1 mA
- Transconductance
- 15 mA/V
- Internal resistance
- Approximately 380 kΩ
- Screen-to-control-grid amplification factor
- µg2/g1 60
- Maximum anode voltage
- 250 V
- Maximum anode dissipation
- 2.5 W
- Maximum screen-grid dissipation
- 0.9 W
- Maximum cathode current
- 25 mA
- Dimensions
- Maximum diameter 22.2 mm and maximum overall height approximately 61.1 mm
- Selection option
- Optional matched/balanced selection on the BTB product page
B9A connections – bottom view
- Pins 1 and 3
- Cathode
- Pin 2
- Control grid g1
- Pins 4 and 5
- Heater
- Pin 6
- Internal shield
- Pin 7
- Anode
- Pin 8
- Screen grid g2
- Pin 9
- Suppressor grid g3
Active-pentode design notes
An active screen-grid circuit must be designed around the EF184 operating point, required signal swing and maximum screen-grid dissipation. Noise and distortion performance should be verified in the completed circuit.
High transconductance calls for short grid wiring, effective supply decoupling and suitable control-grid or screen-grid stopper resistors. The EF184 is an original design option rather than a plug-in replacement for an ECC83 or 6SN7.
Safety notice: Active pentode circuits combine valve high voltage with semiconductor or feedback stages and require correctly insulated, touch-safe construction.
Questions about EF184 audio applications
Is the EF184 suitable for a BestPentode-inspired preamplifier?
Yes, its high transconductance, typical 10 mA anode current and separately accessible screen grid provide an interesting basis for active screen control. The final EF184 circuit must be calculated and measured independently; no type-specific approval by the author of the published principle is claimed.
Can the EF184 operate as a line stage or output-valve driver?
Yes, its 15 mA/V transconductance and typical 10 mA anode current support substantial voltage gain with useful current reserve. The load, screen supply, feedback and required output swing must suit the following stage.
Is matched/balanced EF184 selection useful for stereo?
Yes, electrically similar valves can support closer channel tracking in stereo, differential or balanced circuits. Final channel balance also depends on component tolerances, operating points and the complete circuit.
Note: All brand names mentioned, such as Marshall, Fender, etc., are registered trademarks of their respective owners and are used here for descriptive and compatibility purposes only.
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The EU Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (2011/65/EU = "RoHS 2") aims to exclude certain hazardous substances from electrical and electronic equipment or to restrict the use of certain substances in electrical and electronic equipment. These include substances such as lead, mercury, cadmium, and chromium, as well as certain brominated flame retardants and plasticizers. These substances may only be used in electrical and electronic equipment up to a maximum concentration limit, unless exemptions in the annexes to the directive permit their use under certain conditions. This can reduce and eliminate harmful substances and improve the recycling of waste electrical and electronic equipment. To find out whether the component you purchased from us is permitted in your device, please refer to the current directive or the current law applicable to your country. If you are a manufacturer, please feel free to contact us to find out whether the component you require can be tested and approved according to the current directives. We would be happy to assist you.
Fact sheet on EU Directive 2011/65/EURestriction of the use of hazardous substances in electrical and electronic equipment (PDF, not accessible, 2 MB)
Source: IHK Mittelfranken
Tariff Number: 85408100900
Country of Origin: DE