12AX7
164 Tubes in archive
BrandBrimar
ClassTwin Triode
BaseNoval (B9A)
Filament12.6V @ 150mA
Construction
Primary TypeDual triode
EnvelopeT6-1/2
Base MaterialGlass
Sections2
Filament / Heater
Heater NotesSeries or Parallel connection via heater centre tap (Pin 9)
Absolute Maximum Ratings
Plate Voltage300 V
Plate Dissipation1 W
Grid 1 Voltage-50 V
Cathode Current8 mA
H-C Voltage250 V
Audio Performance
Key Features
- Indirectly heated
- Separate triode structures
- Common heater connections with center tap
- Suitable for AC or AC/DC equipment
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Class A1 Amplifier (Condition 1) | 100V | 1250 | 80000 | 100 | 0.5mA |
| Class A1 Amplifier (Condition 2) | 250V | 1600 | 62500 | 100 | 1.2mA |
Application Notes
The valve is very suitable for use as a resistance coupled amplifier, paraphase amplifier, and cascade amplifier. Separate bias resistors are essential in cascade to avoid instability.
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