JJ EL 34 Octet Power-Tubes matched
EL 34 Octet matched power tubes JJ Electronic
You are ordering an octet of EL34 power amplifier tubes from JJ Electronic, i.e. 8 power tubes.
The JJ EL34 is a very robust and good power amplifier tube that is manufactured in Europe. It is characterized by a very balanced tone and is a perfect substitute for all common EL34 types. It is a Slovak power amplifier tube and brings powerful bass, such as punch in the middle range and clean heights with it.
Amplifier tubes are loosing the sound during the operating time. High frequencies are lost and the basses are no longer as precise. The bad sound is the problem not the volume. From time to time you should replace the power amp tubes with new ones, even if the tubes are not defective. Purely as a sound improvement measure.
In tube amplifiers, you should use only measured power tubes in principle. Matched tubes are tubes with the same values. Tubes deviate from the values much more than semiconductor components. Therefore, one should measure each individual tube and note the values. Then the tubes of the same values are combined, that is called matching. In tube amps, one tube usually reinforces the upper half-wave and the other tube the lower half-wave of the AC voltage signal. If you have an amplifier with more than 50 watts, several pairs of tubes are necessary. If you do not use matched tubes, the power tubes work unbalanced. The current of individual tubes can rise too much, so that they overheat and can go defective, the anode resistor can burn through. The output transformer can also suffer a defect... etc. So use basically measured, matched tubes.
The tubes we offer were factory-measured by JJ electronic. We check and measure them a second time again to make sure that the tubes you order are all guaranteed to work and sound very good.
Each tube has a label with the measured values, so you can buy only one individual tube more. If the power amplifier tubes have been in operation for a longer time, this will not work anymore, as the values of the tubes change their values during their live time. When new power tubes are inserted, the working point should be set new. This can be done with a bias meter. You measure the current flowing through the tube and then set the new appropriate bias current in your amp.
If you want to change the power tubes without having the possibility to measure the bias, you can also send us the old tubes and we will determine the appropriate values and then send back the corresponding replacement tubes. This can only be done if the amplifier has worked without problems before. If the power amplifier tubes were broken due to incorrect bias settings, you have to go to a specialist and have the new tubes set to the right bias. The courageous musician simply swaps the measured tubes and does not measure anything... In most cases this will work, but we cannot recommend it and cannot guarantee it.
Typical values of a JJ EL34:
Power max 25W
Heating voltage 6,3 V
Heating current 1,5 A
Anode Voltage 250 V
Grid 1 -10 to -13,5 V
Grid 2 265 V
Grid 3 0 V
Anode current 100 mA
An overview of all our power tubes EL 34 you fill find here.