Why it was not tied together for pin 1 & 8. Funny thing is there is music when played or is this for 6L6 tubes. This is a push pull configuration. Any advice? Thank you.
I believe pin 1 is the suppressor grid on the EL34. If you are running EL34's pin 1 should be connected to pin 8 which is the cathode. On 6L6's pin 1 was used to ground the outer metal envelope on early metal 6L6 tubes. Mickeystan 🙂
I looked up a EL34B tube and the spec sheet shows the suppressor grid as an independent connection to pin 1. The suppressor grid should be tied to the cathode and that can be done by simply soldering pin 1 to pin 8. I would not recommend running these tubes with a disconnected pin 1 even though the may play music this way (pin 1 disconnected resulting in a floating suppressor grid). Mickeystan
I have seen suggestions of an internal connection between pins 1-8 in EL34-B but I just checked my spare Shuguang EL34-B's and there is NOT continuity between 1 and 8
Now one of the tube is red plating. I measured the biasing current of the EL34 power tube is 200MA. It is too high. No matter how I adjust the bias pot to the min is not helping. What is the cause? anybody can advise. I don't have any schematic diagram.
Even I adjusted from -25V to -5V it doesn't solve the red plating. The valve is good and I swapped around.
the more it redplates..try -30 volts instead of -5.....
.what grid leak resistors are you using?
check that they have not drifted to a high value....
The PSVANE (Shuguang) EL34-B is a strange one.
Pin-8 (Cathode, k) is actually connected first to the Suppressor Grid (g3) and only then via a small wire to the Cathode (k). Pin-1 left floating connected to nothing inside.
Some say that Chinese EL34-B like this are Beam Tetrodes, WRONG, they are true Pentodes but prewired so the user can roll them straight in place of a 6L6GC without worrying about Pin1... Guitarists.
Pin-8 (Cathode, k) is actually connected first to the Suppressor Grid (g3) and only then via a small wire to the Cathode (k). Pin-1 left floating connected to nothing inside.
Some say that Chinese EL34-B like this are Beam Tetrodes, WRONG, they are true Pentodes but prewired so the user can roll them straight in place of a 6L6GC without worrying about Pin1... Guitarists.
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Check for continuity from pin 1 to pin 8 with a mulitmeter for the tube in question. No more guessing.
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