JJ 12AX7 / ECC83S

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

All JJ preamp tubes are selected within a close tolerance and handtested for best sound and quality. Furthermore all pins are gold plated to achieve best electrical contact.
What about the sound? It is still the famous and well known JJ brownsound - warm and smooth.

Files:

• Datasheet

Bias probe for indirect measurement of quiescent bias current of a tube. The adapter is inserted between the tube and the socket and gets connected to a standard voltmeter (not included). Pay attention to the quality of the measuring device and sufficiently charged batteries!

The quiescent current is measured indirectly via a precision resistor integrated in the adapter. The advantages of this measuring method are harmless voltages at the measuring plugs, which are in the mV range, as well as short ways for the current, since it does not need to be fed through the measuring device (common practice with many measuring adapters of Far Eastern production). As a result, there is no risk of oscillations of the amplifier which can lead to possible damage of the tubes or the amplifier itself.

Note: This adapter cannot be used when additional tube brackets are installed. These must be removed before using the measurement adapter and reattached after the measurement is complete.

Procedure for the measurement

Determine the resistance of the adapter, including the measuring leads. To do this, connect the adapter to the meter, but do not plug it between the tubes and the amplifier, yet. Select the measuring range “Ohm” on the meter and note the measured value, e.g. 1,1 ohms.

For the final measurement insert the adapter between the tube and the currentless amplifier and connect it to the meter, select the measuring range mV and switch on the amplifier. When the amplifier has reached a stable operating condition, read the value in mV from the meter and calculate the quiescent current based on Ohm's law.

Example:
measured voltage = 47 mV, resistance of the adapter = 1,1 ohms.
Formula (I = U / R) or in this case:
bias current (in A) = measured value (voltage in V) / measured value (resistance in ohm)
0.047V / 1.1 ohms = 0.042A or 42mA respectively

For the calculation of the correct bias current as well as further information on the bias measurement, please refer to further documents or the bias setting instructions in the info area, as well as the manual of the amplifier itself.

This measuring adapter is suitable for all EL34, 6L6, 6550, KT88, 6V6, 6CA7 and other tubes with the same pin layout.

Attention high Voltage! Measurements and work on tube amplifiers should only be carried out by qualified persons.

JJ 6L6 - #17 - HOT GRADE

• Hot Grade, works perfect with most 6L6 amps
• Recommended for Peaveay 5150 and similar
• Price for one tube.

FAQ: If I order two or more of these tubes, are they all "matched"?
Yes, the tubes are all "matched" and selected for the above amplifiers.

FAQ: Can I change the tubes myself or does anything need to be adjusted?
Adjustment work is not possible on the above amplifiers (unless a bias adjustment has been retrofitted). The exchange can therefore be done without any adjustment or measurement work.

Files:

• Datasheet

Carbon Composition Resistors

• Specification: ½ Watt, axial
• Temperature Range: -55°C to +125°C
• Tolerance: 10%
• Max. Operating Voltage: 350 V
• Size: l=9.5 mm, d=3.6 mm

Carbon Composition Resistors

• Specification: ½ Watt, axial
• Temperature Range: -55°C to +125°C
• Tolerance: 10%
• Max. Operating Voltage: 350 V
• Size: l=9.5 mm, d=3.6 mm

Mica Capacitors

• Voltage Rating:    500 V
• Tolerance: 5%
• Operating Temperature Range: - 50°C / + 150°C
• Termination Style: radial

Vishay ORANGE DROP® 225P

• Type:  Polyester Film Capacitors
• Voltage Rating: 100 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 55°C / + 85 °C
• Termination Style: radial

Vishay ORANGE DROP® 225P

• Type:  Polyester Film Capacitors
• Voltage Rating: 100 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 55°C / + 85 °C
• Termination Style: radial

Vishay ORANGE DROP® 225P

• Type:  Polyester Film Capacitors
• Voltage Rating: 100 V
• Tolerance: - 10 % / +10 %
• Operating Temperature Range: - 55°C / + 85 °C
• Termination Style: radial

• Potentiometer used in many Peavey amp and mixer models like Classic 30.
• Shaft diameter Ø: 4.6 mm
• Screw and washer not included
   

Mica Capacitors

• Voltage Rating:    500 V
• Tolerance: 5%
• Operating Temperature Range: - 50°C / + 150°C
• Termination Style: radial