Elrog 300B vs Takatsuki 300B tubes

I don't mean sonically. Although mismatch can lead to severe sonic compromise or high hum level with sensitive speakers or something else.

Elrog is NOT a drop in replacement. Its specs are NOT compliant with WE's specs, like its plate resistance as one example. What's more important is that there is a proven case which I reported where Elrogs did not work, precisely due the fact that they are not drop-in replacement. For example, they might NOT work with 2 of my 3 300B amplifiers with my sensitive speakers.
Now I know they will work in Frankenstein MK2 but this is 33% success rate in my case. For some people with one amplifier it'll be 100%, for some 0%. Takatsuki to my knowledge has had no such problems so far. They might, but so far I don't know of any such cases.
That's the difference between them.

Online research will lead anyone interested to datasheets of Elrog, original WE's, Takatsuki. Also, there are discussions regarding how some 300B tubes should not be even called 300B tubes. This is all theoretical until it actually does cause problems. All I did is reported a case where it did in practice. And it's very relevant to me and owners of 300B amps.
I can't say yet what it is that causes this amp-tube mismatch. I know of other so called 300B tubes that occasionally have mismatch problems so this is not unique. What I do know now is that Elrog is among them. This is the reason I interfered in this thread. It could be helpful for some.

Dmarkov, I think you do us all a service by issuing a word of caution. Not everyone has the luxury of running expensive experiments. For those who are not in a position to roll the dice on a pair of 1K tubes, it may be well to carefully consider your words. For those that are in such a position, I say go for it.

Optimizing anything related to top tier audio is far from simple. If it were simple, we would all be doing the same thing. Consideration of the physics is alway a great place to start. But it is just a start.

I rolled the dice on the Elrogs pairing with my Frankensteins. It was a risk for sure, given Charles previous experience with, and praise for, the Franks driven by both the Taks and the EMLs. Had the experiment not gone well, I would have kicked myself for not going the safe route, which would have been acting on Charles previous experience and just ordering a pair of Taks. As it turned out, I was intrigued by the novel approach of Elrog, acted on that interest, and was pretty much blown away with the Elrogs right out of the box. I have been far more effusive than is normal in my recommendation of the Elrog 300Bs. For reference, see my caution regarding the Psvane 101D replicas vs the Psvane HiFi series.

Charles had the good fortune to audition a pair of Elrog 845s in a friends system, and based on that, he rolled the dice on the Elrog 300Bs as well.

If you have followed Rebbi's threads regarding driving his Ref 3A deCapos with a low power SET, you have seen caution issued by one of this forums most technically astute contributors, Almarg, with this pairing. After Rebbi's "satisfaction" with said pairing, he provided another astute set of observations that provided some basis in physics for why this pairing may indeed work.

As we used to say back in the chemistry lab, sometimes you just have to stop talking and run the d@Mn experiment.

There is another aspect that impacts all of us. The big gambler was the innovator who took a huge risk both in terms of money buy also in terms of the opportunity cost, i.e. the folks at Elrog. No one is going to take the risk of underwriting the cost of R&D, not to mention product launch, if we as consumers become overly risk adverse and won't try their products. We have to take some risk as well. The NOS well is running dry. The people with actual experience from the golden age of the 50's and 60's won't be with us much longer. It behoves us all to seize the moment.

I say folks try the tubes. If you don't like them, sell them.

Brownsfan, thank you and I agree with your points and hats off to people behind Elrog and Takatsuki. Charles1dad's and your experience with Elrogs in Franks is very good news for owners of Franks, me included. They are cheaper than Takatsuki after all!
But I am making 2 points that I think are also very important/valuable in this thread and I will not allow them to be mellowed down :))
1. Elrog is not a 100% drop in replacement and is not suitable for any 300B amp. With more statistics we will know where it's working.
You are totally right. I will even add that people with means actually owe it to the bravery and risk of the people behind new Elrog to buy, try and compare to other great tubes :) But try to hear Takatsuki too if you can. It's not difficult to beat PSVANE T2 these days except it's totally amazing for its price and I often recommend it.

2. The fact that Elrogs are better in Franks (yes, a matter of sonic preference but I trust Charles' experience) does not guarantee they will be preferred in other amps over top tubes.
This is not a mere speculation. I mentioned much less successful listening experiences where other tubes were preferred to Elrog (old WE's and Takatsuki). So at this point my only take out is that they work exceptionally well in Franks, and that they are better in Franks than Takatsuki (yes, preferences may differ, let's say there is a big chance they'll be preferred), and they are cheaper!

For other amps - not at all that clear, and for some ampd - not recommended. I will keep an eye where it works and where it doesn't. It would be great to sometime do a list. If I hear anything like this about Taks, I'll report too.
I posted some photos of my system, there are some tubes there. When I test, I also try to test in several systems and with several pairs of ears to make sure it's not a one off.

I'm not a technical person and don't claim to be. Everything I've read up to this point has stated the Elrog is a direct replacement for the 300b as they matched the filament current and voltage requirements. I accepted this as fact and had no logical reason to doubt it. If there are certain amplifiers(for what ever reason) that can't use the Elrog this should be made known(thanks Dmarkov). I suspect they may be a minority. Based on a goggle search I did to read other Elrog user's experiences, it seems the vast majority have had positive outcomes.

At this point with this relatively new tube, more information will be gathered and some level of compatibility will be known over time. I would never expect that everyone will always prefer the Elrog over other worthy 300b competitors. There are simply too many different ears and amplifiers/systems for that to be the case.
Charles,

The Elrog has a different internal impedance, gain and filament type to a conventional 300B. Internal impedance (resistance) is approx 900R vs 700R, gain is higher than a standard 300B and the filament is thoriated tungsten type vs oxide type. It will give less power than a standard 300B under the same conditions.
Elrog recommends to use the tube into higher impedance output transformer loads than a conventional 300B because of the higher internal impedance.
It can have a problem in an amplifier that was designed around 300B specs as it did in the case I mentioned. Problem = mismatch and sound compromise.
Voicing/sound of the tube is different from "standard" 300B but this could be either good or bad, users can decide for themselves.
In absence of proof that it works in a particular amp, like with Franks as we have here, or when one has no possibility to just get a bunch of tubes and hear them in his own amp, it could be wise to contact the amp designer for advise. More experiences similar to the one with Franks will tell the story eventually.