ECC81JJ 12AT7 JJ tubes V1+low mic+lownoise Röhren Set
Two V1 valves selected for low noise, low hum and low microphony use
For driver, phase-inverter, reverb and audio preamplifier stages
Optional matched/balanced grading suits stereo and balanced stages
JJ ECC81 / 12AT7 – low-noise and low-microphony V1 set of two
This set contains two current-production JJ ECC81 valves. The ECC81 or 12AT7 is an indirectly heated medium-mu dual triode with comparatively high transconductance and a nine-pin B9A Noval base.
BTB selects both valves for sensitive V1, driver and phase-inverter positions with attention to low noise, low hum and low microphony. An optional matched / balanced selection of all four triode systems is available.
Suitable applications
- Driver stages in valve amplifiers
- Phase-inverter and long-tail-pair circuits
- Compatible reverb drivers and oscillator stages
- Hi-fi, line-level and studio preamplifiers
- Stereo circuits using one ECC81 per channel
- Equipment explicitly specifying ECC81, 12AT7 or 6201
BTB selection and options
- Package contents
- Two JJ ECC81 / 12AT7 valves
- Standard selection
- Checked for low microphony, low noise and low hum
- Matched option
- The two valves are grouped for closely corresponding electrical measurements
- Balanced option
- The two systems within each dual triode are selected for closely corresponding values
- Country of origin
- Slovakia according to the current BTB product information
Technical data
- Valve type
- Indirectly heated medium-mu dual triode
- Type designations
- ECC81, 12AT7 and 6201
- Base
- Nine-pin B9A Noval
- Heater voltage
- 6.3 V in parallel or 12.6 V in series
- Heater current
- 300 mA at 6.3 V or 150 mA at 12.6 V
- Typical operating point per system
- 250 V plate voltage, -2 V control-grid voltage and 10 mA plate current
- Amplification factor
- Approximately 60
- Transconductance
- Approximately 5.5 mA/V
- Plate resistance
- Approximately 11 kΩ
- Maximum plate voltage
- 300 V per system
- Maximum plate dissipation
- 2.5 W per system
- Maximum cathode current
- 15 mA per system
- Maximum heater-to-cathode voltage
- 90 V
- Dimensions
- Maximum diameter approximately 22 mm; overall height approximately 54 to 56 mm depending on production
Pinout and heater wiring
- Pins 1 to 3
- Plate, control grid and cathode of triode system 1
- Pins 6 to 8
- Plate, control grid and cathode of triode system 2
- Pins 4, 5 and 9
- Connections of the split heater
- 6.3 V heater connection
- Join pins 4 and 5 and apply the supply between this connection and pin 9
- 12.6 V heater connection
- Apply the supply between pins 4 and 5; pin 9 remains unused
Comparison with ECC83 and ECC82
- ECC81 or 12AT7
- Amplification factor around 60, high transconductance and normally greater plate current
- ECC83 or 12AX7
- Greater amplification factor around 100 and substantially higher plate resistance
- ECC82 or 12AU7
- Lower amplification factor and a different optimum operating point
Selection and application notes
The ECC81 is not electrically identical to an ECC83 or ECC82 despite the related B9A pin arrangement. Gain, operating point, plate current and heater-to-cathode limit must suit the circuit.
The high transconductance can encourage parasitic radio-frequency oscillation with long wiring or missing grid stoppers. Short wiring and effective decoupling are important.
The matched / balanced option can provide additional value in phase-inverter, differential and stereo circuits. In a simple driver or V1 stage, acoustic selection is often more important.
Disconnect and discharge the equipment and allow the valve to cool before replacement.
Questions about selection and use
Is the JJ ECC81 / 12AT7 V1 set suitable for driver and phase-inverter stages?
Yes, the JJ ECC81 / 12AT7 V1 set is suitable for compatible driver, reverb, differential and phase-inverter stages specifying an ECC81 or 12AT7. The operating point, heater wiring and heater-to-cathode voltage must match.
Can the JJ set replace two existing ECC81, 12AT7 or 6201 valves?
Yes, the JJ set can replace two compatible ECC81, 12AT7 or 6201 valves when the limits and circuit function agree. An ECC83 or ECC82 is not an identical substitute despite the related base arrangement.
Is the matched / balanced option useful for stereo and phase-inverter stages?
Yes, the matched / balanced option is useful for stereo, differential and phase-inverter stages because it supports closely corresponding values between both valves and across all four triode systems.
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.
JJ-Electronic s.r.o.
SK-02201 Cadca
Email: info@jj-electronic.com
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: 85408100
Country of Origin: SK