Radiotechnique 12AU7/ECC82/6189 Sonics

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( http://www.tubeworld.com/12au7.htm ).

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.