Are you kidding me!? Really!?

[MWJB]

"I can hardly hear the difference between a 9W amp and a 12W one (30% difference)" I'm sure that you are just saying that for effect, there are more factors that affect a tube's sound than it's wattage rating. Most people can hear the difference between tubes of similar wattage ratings, even between different tubes of the same brand, and show their preference accordingly.

[JoeM]

Is there really a need for a lower diss EL84? I would think a more durable version, both mechanically and electrically would be higher in demand. I just dont think "headroom" and "EL84" in the same sentence. Looks to me like Eurotubes is trying to market a crappier tube.

[J M Fahey]

"I can hardly hear the difference between a 9W amp and a 12W one (30% difference)" I'm sure that you are just saying that for effect,

No, I'm saying it literally.
Do you want to make the experiment yourself ?
Use a tapped power transformer, which can supply, say 300VDC or 250V DC at the flick of a switch, whatever's necessary to make the amp clip at either 9 or 12W RMS.
You leave the room, someone else flicks the switch at either position, you enter the room, play whatever you like, and say "this amp has "X" watts", which is duly noted.
Leave the room, wait 5 minutes, come back and repeat the experiment.
Repeat at least 10 times, preferably 20, and check your opinion against hard fact.
Everything else is kept the same, speaker, guitar, etc.
You should mark a circle in the floor so you stand always in the same place.

[MWJB]

I have done experiments many times myself, as have many others, using tubes of similar rated wattage...they sound different - so I don't doubt that if JJ have a new tube, different to the regular EL84, that sounds different.

Why would you switch B+ in your experiment, why wait 5 minutes & leave the room? That's not a comparison, if you have trouble retaining a sound in your memory use a control & a test amp, as identical as possible, & switch between the 2. Your methodology is flawed. A 50v change in B+ will be obvious to hear, you dont say how you compensate for the change in idle current.

[mooreamps]

For the record...the screen voltage controls where those curves are anyway so why not just lower the voltage to the screens like lots do with power scaling?

Because with a Plate Rail regulator ; the waste heat dissipation is too high.

-g

[Wilder Amplification]

Because with a Plate Rail regulator ; the waste heat dissipation is too high.

-g

Why would you need to scale the plate rail for scaling screens?

[Alex/Tubewonder]

How well a tube measures vs. the specs is what makes a an El84 or whatever you want to call it. Not what the anode is made of. Material wise the cathode coating material and its activation process during manufacture accounts for much more.
Regarding the new JJ offering a study of available data sheets and comparison to EL83 - which eurotubes claim the EL844 is not - I'm leaning towards agreeing that it's not EL83. But nobody said anywhere that EL844 isn't a repackaged, to make it pin compatible with EL84, russian 6P15P. Circumstantial evidence and paper trail make a strong case: 6P15P data sheet.
JJ typical parameters differ from those in 6P15P data because they are quoted at different operating conditions. Nice one JJ ;-)

[MWJB]

Alex, are you aware of any other tubes that JJ offer that are re-pinned, repackaged Russian tubes?

Perhaps someone really has the inside line on the EL844, rather than speculation/conspiracy theories?

[Alex/Tubewonder]

Alex, are you aware of any other tubes that JJ offer that are re-pinned, repackaged Russian tubes?

Perhaps someone really has the inside line on the EL844, rather than speculation/conspiracy theories?

No, I am not aware of any de facto re-branding of russian tubes by JJ. As you say, it's a speculation based on data sheets analysis. Since JJ came to be as result of management buy-out from old Tesla I would imagine they got not only production lines but also all technological documentation. In the old days of cold war - there was a lot of coop between East European tube manufacturers so it is not impossible that Tesla would be manufacturing for the sovjets etc. If so then it should not be a too difficult task for them to do a reissue and pin it to be compatible with EL84. The problem, from marketing point of view, is that NOS 6P15P can be had for around €1.5 so you need an angle to justify the €11 price, hence EL844. On the other hand, if you want to achieve similar effect to what EL844 claims get a 6P1P, all you need to do is rewire the sockets but the tube is spec-wise close to a 6V6 in a noval 9-pin bottle. You won't even need to re-bias a fixed bias amp as you will need to do with EL844. There are lots of cool east european (soviet) tubes outside of the top 10 list that make for very advantageous economical alternatives for the D.I.Y. community. Just study the data sheets.

[Jazz P Bass]

My earlier post stated that at a fixed temperature the cathode can & will supply "X" amount of electrons.
No more. No less.
The plate voltage will attract them.
The grid voltage will allow them through.

I never got the plate material jist of this thread.

[Alex/Tubewonder]

When I mentioned plate material I was alluding to a statement on eurotubes site where they assure us that EL844 is not an EL83 because plate structure has different shape. Which is even more ridiculous than claiming different grade of steel used for plates. I should have been clear on this point in my earlier post.