JJ 5751

2 tubes, matched as pair

Mullard reincarnated. With the EL34EH, Marshall amp owners can recreate the balanced tone, deep, tight bass, sweet mids, and well-defined highs of the original equipment Mullards. Innovative design and precision construction give the EL34EH exceptionally smooth and an ideal balance of pleasing even-order harmonics while virtually eliminating undesirable odd-order harmonics.

Files:

• Datasheet

Electro-Harmonix has released a low noise, low microphonic version of the 12AX7 that meets all specifications required for the tube to be designated 7025. The original 7025 tube was a 12AX7 that was tested and selected for the lowest noise and microphonics for use in the critical first preamp stages of amplifiers where noise and microphonics could be an issue. In order to ensure that the 7025 specification is consistently met, Electro-Harmonix has redesigned the structure of the 12AX7 and has implemented construction techniques to ensure the absolute lowest noise and microphonics possible. In all samples tested, noise and microphonics could not be detected.

The Electro-Harmonix 7025EH has a mid-range that gives clarity and definition to the sound and a smooth top end for warmth and balance. With these characteristics, along with the exceptionally low noise and low microphonics, the Electro-Harmonix 7025EH will work equally well in vintage and modern high-gain guitar amplifiers, as well as sensitive phono preamps.

• Fender#: 002-8421-000
• Hum Control Potentiometer
• Without nut and washer.

JJ's version of the ECC81/12AT7 tube type with a warm and soft sound. Often used for phase inverters or reverb drivers.

Files:

• Datasheet

Very linear working 12AX7 / ECC83 with long anode plates and spiral heating, which makes the tube less sensitive to interference from AC heating.
We recommend this tube for audio and high-end amps as well as for "modern" Fender amps with more overdrive, but also as an input tube in old Marshall JCM800s.

Note: Tubes equipped with long plates are commonly associated with a "warmer" or "richer" sound, whereas those with shorter plates tend to deliver a "tighter sound". However, tubes featuring long plates exhibit increased sensitivity to vibrations and mechanical disturbances, rendering them less ideal for critical applications.

Files

• Datasheet

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.

Metallized Polypropylene capacitor

• Voltage Rating: 630 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 40°C / + 85°C
• radial
• self-healing
• non inductive

Metallized Polypropylene capacitor

• Voltage Rating: 630 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 40°C / + 85°C
• radial
• self-healing
• non inductive

Metallized Polypropylene capacitor

• Voltage Rating: 630 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 40°C / + 85°C
• radial
• self-healing
• non inductive

Resistor Metaloxide 2 Watts

• +/- 5% tolerance
• -55° C to 240° C operating range
• Max 500 V
• Excellent flame retardant coating
• Different manufacturers

Please note:
These resistors have a very small form factor:
red: l = 10 mm, d = 3.9 mm
green: l = 11.5 mm, d = 4.5 mm

Metallized Polypropylene capacitor

• Voltage Rating: 630 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 40°C / + 85°C
• radial
• self-healing
• non inductive

Polyester Film Capacitors

• Voltage Rating: 630 V
• Tolerance: +/- 10%
• Operating Temperature Range:c- 55°C / + 125 °C
• Termination Style: radial

Polyester Film Capacitors

• Voltage Rating: 630 V
• Tolerance: +/- 10%
• Operating Temperature Range:c- 55°C / + 125 °C
• Termination Style: radial