FLEA 251 - Is it worth replacing the tube?

I think bowie would be the guy to ask? I’m not sure but I think the GE 5 star orange ink 6072a is the holy grail, the orange ink designating the quieter widest bandwidth operation for audio?(I could be way off or confusing this, it’s been a long time since I read about mic tubes)
That said I have 2-C12 and 2-251 clones, I have the rare orange and green ink 6072’s in them and they didn’t end up in the mics by accident and only after a whole lot of comparisons

In short imo the tube matters

I’m always a Mullard fan. Can’t remember if they call it a 6072 or 12ay7, but it was more rolled and beefier than anything else I tried.

This isn’t a Flea question. It will affect all of them the same way. A Mullard is going to add bottom, rolls top. Not nearly as bright as the GE.

Okay, at the moment with the EH 6072a, FLEA has now much bottom and rolls top compared to BSA M250.
So this is good, but I want a little more top highs (>11khz)

GE 5 star orange ink 6072a

Never heard from that, or do you mean the red painted tip ones, selected medical grade?

While the GE 6072s all sound like they're from the same family, they do vary a bit as they went through numerous changes during the 35 year production run. I'd say the GE 6072 sound is natural, smooth, and articulate, relative to other 6072s. But, there's some variations in tonal balance and the level of  focus or "cohesion" (tight and defined vs being more wide and diffuse). As far as differences with modern tubes go, since the GEs don't all sound the same, what differences you hear will vary on the version of the GE. I'm frequently told that users find the GEs to be smoother than Russian types. And, I often hear comments about them offering a greater sense of "depth" (which is usually a combination of fine detail and harmonics overtones). Some prefer the warmer/richer sound of the early production GEs. Others don't like the low-mid weight of those early types and prefer the more neutral aspects of the later production GEs. There's no scale of good/better/best. It's really down to the user as to which type they prefer and opinions vary greatly. Some prefer one type in a certain mic, and a different version in another mic.

As far as 5-Star goes, there's a lot of internet lore involved there. I used to do business with a retired GE engineer who worked in tube design and was told that there was no difference in 5-Star or non-5-Star when all else is equal. And, that it was mostly down to marketing and who they were selling them to. "Do you think we sent the noisy ones to the military?" he jokingly said. And, having tested thousands of 6072s over the years, I have not found the 5-Star labeled pieces to consistently be any different in quality or sound from those labeled without 5-Stars, if they were produced in the same way. Now, batches can vary, especially the early ones. GE labeled many of their high-spec tubes as 5-Star so consumers would know it's not a regular 12AY7, or 6AQ5, 12AT7, etc. I have no evidence that they went through a run and designated some pieces as 5-Star quality and other not. That doesn't seem to be the case at all. However, internet lore says otherwise so expect to pay much more for a 5-Star labeled piece because they are in much higher demand. I believe part of this fueled by the fact that the more common GE 6072s are the late run "JAN" types with green labeling. The quality of these is often poor and I believe people may have associated these lower quality pieces with being non-5-Star GE 6072s.

 Generally speaking, I wouldn't say any of the GE versions are necessarily more detailed than the other, but it depends where the user is listening for detail. "Detail" is one of those things that seems cut and dry, but is interpreted in many ways. Though we all sort of speak the same language on the forums, when I talk to people about what they're hearing in their gear it's amazing how differently people hear things. Even guys that work in the same studio with the same gear will often have different perceptions. Many listen for detail in the highs, so they might hear the later production tubes (be they JAN, 5-Star, etc) to be more detailed. But, those who favor warmer tones will notice that the low-mids on the early production tubes are more detailed and defined than the later GEs. 

Generalizing anything with these is tough as there's so many variations. For instance, "JAN" was used as far back as the 1960's, and there's even white-label JAN. There's also green labeled 5-Stars.