Radiotechnique 12AU7/ECC82/6189 Sonics

Radiotechnique 12AU7/ECC82/6189... What's the sonic difference between the long and short plate versions? Is there any difference in the various years of manufacture? Which version is the "best"? Versions to avoid?

I'm exploring tubes for my DAC. So far I like the Sylvania 6189. But I'd like more warmth, without going the mushy Mullard route.
That's the branch of Philips Holland, that manufactured tubes in France. Some of the best(small plate) were made in the late 50's. They made another 12AU7WA(longer plate), around 1965, that was nice tube also. Either should prove cleaner and more open, than most Mullards(even though Philips owned them too). Philips Miniwatt or Amperex Bugle Boys(same company) might appear on your short list as well. If you still want less warmth/ more accuracy; try pre 60's, Siemens ECC82( ).
Tubes with long plates tend to be more microphonic which can be good or bad depending on personal taste.Sometimes you can "tune" them just right with O rings or Herbie's tube dampers.If you are interested in reissue tubes at all,JAN Phillips 12au7 I have found to be slightly warm with excellent highs and bass.The Gold Lions have a beautiful midrange,a full and natural bass,and very good highs after about 20 hrs. of break in.Hope this helps,best of luck as you experiment!
Thanks for the input, but a broad coharacterization and general history isn't what I'm looking for. I'm interested in the specific sonic differences between the long and short plates, between the various years of each, and between the 12AU7 and the 6189 versions.
Apparently there were some long plate versions of the made in 1958.
No one call tell you, specifically, what any tube will sound like, in your system(too many variables). Good luck, trying to find someone that has that kind of experience, with all versions of Radiotechnique's 12AU7's. Radiotechnique has never been what one would consider a, "mainstream" or "popular" NOS tube(ie: Siemens, Telefunken, Amperex, Mullard, Brimar, etc), BUT(who knows)- there may be someone out there, that loved the company's products. Happy listening!
I don't expect to find a single person with comprehensive knowledge of this tube, but surely there are a few with enough exploration of it to be able to piece together a sonic profile. Moreover, I don't believe the audio world is so utterly atomistic that nobody can sat what any tube sounds like because of the uniqueness of every circumstance. What I'm interested in, specifically, is the difference (if any) between the long and the short plates, and between the regular 12AU7 and the 6189.
Sorry for coming in on this a bit late! (New member.)

In my collection there are three plate sizes, not two. The long one is about 17mm, medium is ~14mm and the short is a folded ~11mm plate. I like them in their own way, and yes it all depends on your system, tastes, etc, but for me the medium length is the best. Here is a summary of some of my thoughts:

-short: very sparkly and present (upper mid-range hype) that appeals to a lot of people who first hear it. Nice for sure, but for me a bit too much like eating cake icing all day.

-medium: the most 'natural' of the group and with several variations (5814, 6189, various getter supports etc). My favourite. Can't go wrong with the variations. The 12AU7S can be breath-takingly clear but also the least 'warm' of the group. The regular 12AU7 (single getter support) is probably the 'warmest' with the most harmonics, but can lack some of the clarity of the others. The 12AU7WA 6189 with the double getter support is a nice balance between the two. But they are all great and this is one of my all-time favourite tubes, no matter what variant. Recommended.

-long plate: 'scooped' sound (more lows and highs, less mids). I have a soft spot for this style since it was one of the first decent tubes I ever bought. But, truth be told, it is probably the least audiophile of the three. But as I said, it all boils down to your system and your tastes.

RT was owned by Philips, but I have never heard a Dutch Philips sound like these (not even the famous 7316). The medium length is one of the most under-appreciated tubes around, with not a lot written about them that I have found, but they are getting very hard to find (at a decent price) which makes me think that people are quietly snapping them up.

Hope that helps...

Many thanks for you very informative response, very helpful!

I’ll just add on, at this point and for whatever it may be worth: the 12au7wa 6189 is a stunner tube. I have not compared it to the other RTs but to Brimar 12au7. It’s very extended both too and bottom, with higher saturation/density and color. I have 4 running in the gain of my PL Evo400 pre. I will say you can have too much of a good thing with these. Ex: I put two more in the gain section of my Evo400 amp, and it was like too much rich icing on a cake. I keep the Brimars there; quite and more formal and orderly sounding.