TT 12AT7 / ECC81

Warm and balanced overall sound, paired with high resolution and brilliance, which is why the TT12AT7 achieves the best results in both instrumental and audio/high-end amplifiers.

Features:

• Warm and balanced sound
• Excellent sound resolution and brilliance
• Ideal for instrumental and audio/high-end amplifiers

Hint;
Often, 12AU7 and 12AT7 types are used instead of 12AX7 tubes in order to either reduce the overall power of the amplifier or just take back the overdrive of the preamp. Especially the 12AU7 brings a very large tonal difference compared to a 12AX7, which is usually much greater than when switching from a 12AX7 to 5751 or 12AT7.

When using a 12AU7 in a driver stage that is normally designed for 12AX7, the overall power of the power amp is usually reduced. How big this difference is depends on the amplifier or circuit. For example, a Marshall with a 12AX7 in the phase inverter stage set to volume 5 will then reach the same volume with a 12AU7 set to volume 6 (perceived volume, not measured).

Electrical Characteristics

• Heater Voltage (Uf): 6.3V or 12.6V
• Heater Current (If): 300mA at 6.3V, 150mA at 12.6V
• Anode Voltage (Ua): Maximum 300V
• Grid Voltage (Ug1): -2V (typical)
• Anode Current (Ia): 10mA (typical)
• Anode Power Dissipation: Maximum 2.5W per triode
• Anode Resistance (ra): 11kΩ
• Amplification Factor (μ): 60
• Transconductance (S): 5.5mA/V
• Input Capacitance (Cin): 1.6pF
• Output Capacitance (Cout): 1.6pF

Mechanical Characteristics

• Socket: B9A (Noval)
• Number of Pins: 9

Pin Configuration

• 1 Anode (Triode 1)
• 2 Grid (Triode 1)
• 3 Cathode (Triode 1)
• 4 Heater (f)
• 5 Heater (f)
• 6 Anode (Triode 2)
• 7 Grid (Triode 2)
• 8 Cathode (Triode 2)
• 9 Center Heater (f)

Application Notes

• Heater Operation: The tube can be operated with either 6.3V or 12.6V, depending on the circuit design.
• Grid Resistors: It is recommended to use grid resistors of at least 1MΩ to ensure stable operation.
• Coupling Capacitors: Capacitors with low capacitance (typically 0.1µF) are recommended to minimize high frequency disturbances.