Rolled some 12ax7's recently...

abuck...yah..I have some of those. They get good reviews in various places on the web & they are good. Whether they are better than the others I mentioned depends on how each sounds in your system. Every setup is unique in many respects.

Ruggedized means stronger not better. All tubes should be checked for microphonics on an individual basis.
That would be like saying Queen Latifah is a better singer than Beyonce because she outways her by 100lbs.
Rugged makes a Marine not an opera singer.

Magnum, I do think stronger is better for the reasons I already detailed. I believe what you're saying is that stronger doesn't necessarily mean better SOUNDING, and except for the 3-mica 5751's near total lack of microphonics, I wouldn't argue with you.

I also mentioned (and this is admittedly my own experience) the fact that for reasons beyond my understanding, the 5751's (generally) have a smoother presentation than the 12AX7's I've heard (which in my case includes most of them.) "Smoother" being my own term for a less grainy or maybe more liquid(?) sound. YMMV
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I just spun two new records (both 180g vinyl) -- Rickie Lee Jones, Rickie Lee Jones and Pop Pop. Interesting result when I swapped out Bugle Boy and JJ 12ax7's.

Background: I recently won a Denessen Soundtracktor on ebay and decided to align my cartridge with it. I had used the Alphason protractor that came with my HRS-100, originally. I was using some new JJ 12ax7's that I got for cheap and noticed they didn't sound half-bad after breaking in. When I aligned my cartridge with the Denessen, I noticed that voices opened up, there was more air, and the soundstage generally cleaned up, but the bass was so thin that I really thought I had better start researching good sub-woofers.

Tonight when I received these two records and spun them I thought I would put the Bugle Boys back in the pre-amp. Of course I listened with the JJ's in at first.

Well, with the Bugle Boys I immediately realized that I don't need a sub-woofer in my current set-up and room. It was such an amazing contrast! Truly immediate and night-and-day. I know that JJ's are basicaly run of the mill 12ax7's, but I never would have guessed nor imagined that the difference would have been so dramatic. I am truly glad that I have 3 matched pair of the Bugle Boys! It will be a long time before I need to use the JJ's.

Besides the incredible difference in bass, I also noticed timbral, soundstage depth and width, mid-range, and high frequency improvements that were significant. On the high end, I noticed a raspiness or edge with the JJ's that disappeared with the Bugle Boys. I thought that the records, being re-mastered were perhaps badly pressed. The edge and rasp disappeared with the Bugle Boys.

My conclusion is that when I look for replacement tubes, it is worthwhile to seriously consider NOS tubes rather than current production ones. I have not listened to re-issues, that is why I say, "consider."

I am really interested to hear from anyone who has experience with re-issues compared to NOS tubes. That might be an interesting tube-roll. Certainly my conclusion so far is that NOS 12ax7's are much, much better than current production JJ 12ax7's. It's a pity to think that good current production 12ax7's are so lame -- what to do when it is time to buy new tubes? Another question I have is, is there such a dramatic difference between current El34's, or other power output tubes, and NOS El34's?

Here's the only new production 12AX7 worth thinking about, if you are able to appreciate the differences/improvements in sonics that the right NOS tubes provide(and it's obvious you do): (http://www.musicdirect.com/product/73403) With regards to EL34s: It's been quite a while since I've used that particular output tube, and had Svetlanas last(the original company was still in business). I've found the Winged 'C' 6550 to be an excellent replacement(sonics and reliability) for the NOS outputs that I used to be able to afford in my present amps. Matched octets of anything worth considering in NOS outputs are virtually impossible to find now. If Siemens made a 6550, I'd have to try them. Consider these, or the Winged 'C'(St Petersburg plant), for your EL34 needs: (http://www.upscaleaudio.com/Siemens-EL-34_p_62.html) (http://www.upscaleaudio.com/SED-Winged-C-EL-34_p_63.html)