I had goodluck with GE triple mica blackplates 5751's.
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I've tried a few of the popular old and new 12ax7/5751 tubes in my JD100, and in the long run, I stuck with the new Sovtek 12ax7lps. Maybe not the best overall tone, but the dynamics are much closer to "lifelike", over anything I've tried. And, they're very quiet.
Some people claim the earlier production ones are better then the newer ones. Mine are year 2000.
An old tube equipment builder/tech suggested to me to try some 12BZ7's, for some real dynamics, but I'm not sure how the JD100 would react to the additional draw, and since they are taller, I don't think they would clear the top cover.
I tried the Sylvania 5751 triple mica black plate and loved the richness, but not the heavy bottom end. Went back to the Svetlana 12ax7's until someone posted something about the Chinese Full Music 12ax7's. I bought a pair for around 70 dollars, and found they were very comparable to the Sylvanias, but balanced across the board in my system. Sold the Sylvanias, love the Full Music!
I googled 12BH7s and found interesting info about them. They have equal gain (mu) to 12AX7 but draw twice plate current and give off a lot of heat.
People who have used them in Jolida amps say they increase the soundstage and are more dynamic.
Also, Cary six-pac owners use them because they increase watt output and decrease distortion.
Like you I don't think I would use them because I'm not sure how the circuitry would respond to extra heat current.
Also because of their size they are microphonic, but that can be tamed by using a Herbie's Halo.
I think you'll like these. The Svetlanas I was using lacked good bottom end, so I put down some serious money for the Sylvanias, which really improved pretty much everything. But they brought along some serious bottom end, a little too much for my liking, so I went back to the Svetlanas. I read a post here on A'gon about the TJ Full Musics, and did what you did. I feel they are just as good as the Sylvanias, if not better. They are balanced from top to bottom and sound great! If I remember correctly, they didn't take a real long time to break in. Keep us posted.
I recently bought a pair of the TJ Full Music 12ax7's for my McIntosh C220 preamp. A significant improvement over the stock tubes. I have about 50 hours on them and they are not coming out of my preamp any time soon. I had tried a pair of Telefunkens and I prefer the TJ Full Music tubes. Very smooth, full-bodied and balanced across the audio spectrum. I have no affiliation with the company and I don't know how they will sound on other equipment but on my McIntosh they sound great.