Modern EL34 reliability?

[Helmholtz]

Or someone made an error.

That's what I was hinting at.

[Chuck H]

Good question, provided we are speaking of the same tube.

The whole story seems obscure to me. I mean, why should a manufacturer give his tetrode the name of a classic pentode? Tetrodes and pentodes can't have exact same charts: different curvatures and screen currents.

If the EL34B actually was a tetrode and behaves like a KT77, why not call it a KT77?
(IMO, the KT77 is the more advanced design.)

Well anybody that's been doing anything with tubes for the last twenty years will attest that many of the Asian tube manufacturers are selling products that are not consistent with their designated model, but publish data regurgitated from the old RCA, Sylvania, etc. tube charts. I mean EXACTLY the same indications for voltage, current and loads that the old data sheets have. Like they just copied it regardless of what the tube they're selling does. For years the JJ 6V6 was thought to be one of their bigger bottle tubes jammed into a smaller bottle and people were punishing them with as much as 500Vp. But the early data sheets had the same old specs as the vintage RCA sheet. The Sovtek 5Y3 use to have a MUCH smaller voltage drop than any real 5Y3 but their early data sheets were also the same as the vintage sheets.

[Helmholtz]

Seems the facts speak for themselves. And facts (as opposed to internet rumours) is all I am interested in.

[Diablo]

Yeah the three grids shows the EL34B proves it’s a pentode. I got my mis information from the tube store, sorry about that.

https://blog.thetubestore.com/birth-...b-vacuum-tube/

[Chuck H]

This is interesting. Trying to look up a datasheet for the Shuguang EL34-B offers this site first above all others. This site goes into some detail, repeatedly stipulating that the Shuguang EL34-B is a tetrode. Expressly stating it is not a pentode. Even on the page that shows a diagram of the tube with three grids and no beam directing plate.

http://analogmetric.com/download/Shu...%20Limited.pdf

[Enzo]

How I read it: They say EL34B is in the tetrode group, while EL34A is a pentode. They add that the G2 and G3 are not exactly aligned. Just my opinion, but it seems that in the EL34 the g2 and g3 should be aligned, and this mis-alignment in their view means they consider it a tetrode. In other words it is a pentode that they feel must be considered as a tetrode.

Any meat on that bone?

[g1]

Agree that they are a retailer and don't seem to know what they are talking about.
My take was that they said EL34B was 30W not 25W like the EL34A so maybe they were thinking the extra watts were because it was beam rather than pentode.
Then they went on to show the power as 25W in the specs., lol.

And their 5881 they showed as 23W then said it was good for sub as 6L6GC.

So then I went looking for some actual Shuguang data and found Changsha Shuguang Audio but it turns out they are a retailer as well, even selling Sovtek. Real Shuguang is Shuguang Electron Group who's website is now defunct.

[Chuck H]

Real Shuguang is Shuguang Electron Group who's website is now defunct.

Well aw $h!t.!? Now I'll have to learn to make vacuum tubes too? Where the hell is Juan!?!

[Enzo]

My mom had a vacuum tube, she hooked it up to her Hoover.

[Diablo]

How I read it: They say EL34B is in the tetrode group, while EL34A is a pentode. They add that the G2 and G3 are not exactly aligned. Just my opinion, but it seems that in the EL34 the g2 and g3 should be aligned, and this mis-alignment in their view means they consider it a tetrode. In other words it is a pentode that they feel must be considered as a tetrode.

Any meat on that bone?

Maybe I’ve got it wrong, but the secret sauce for making a kinkless beam tetrode is careful alignment of the signal grid g1 and the screen grid g2 + the added beam plates tied to the cathode. A pentode doesn’t have g1 and g2 aligned, but does have g3 to keep electrons flying off the anode from going to the screen. The tetrode makes a virtual suppressor grid by focusing the electron beam in front of the anode. The concentration of electrons keeps anode electrons from flying backwards toward the screen grid.

https://m.youtube.com/watch?v=Zh_51RP4V6I

[Enzo]

Diablo, you are probably correct, but insofar as you quoted me, I have to point out I didn't mention g1. My surmise - and it was only that - involved g2 and g3.

[drewl]

You guys should be in charge of designing new EL34's.

[Diablo]

You guys should be in charge of designing new EL34's.

I’d rather be in charge of the Marketing dept, with a big expense account.
I’d call the new tube an ENZO34.

[Enzo]

You will need a pretty big expense account to make that float.

I never thought to find out...vacuum tube do float, don't they?

[g1]

Not on air. I tried that once & learned pretty quick.