Tube ---- Ei 12ax7

I use and find the recent production EI's to be excellent in all but two respects - they are not overly warm but they produce a very clean clear sound. They are not etched or cold sounding. The currect EI's are having quite a bit of quality control issues (best to buy more than you need, some will certainly fail). Older production grey plates are quite good, and usually fairly quiet. I have not enjoyed the EH's as much - reminds me of the sound from Sovtek 6922's, cold and uninvolving so to speak. Have not heard the RCA's or the GE's.

Thanks Newbee =)

I should have gone on to mention that the particular Ei's are actually ECC83 Low Noise, I believe there is some differentiation from the regular Ei's. (tube designation 12ax7ln)

I have heard that Ei has had some problems with QC as well as microphonics.

To me the EI 12AX7 is the best production tube of this type (less colored, more defined and extended, cleaner), though I've never tried the new Svetlana's. I have found the newer shiny-plate ones to be as good as the older gray-plate ones. For high-gain stages, like a phono input amplifier, you'll have to go through several of these tubes to find one or two having acceptably low noise and microphonics. But for less critical stages, which is what I'll assume you're dealing with here since you've substituted NOS 5751's, the rejection rate should be within reason. (BTW, the ECC83 is the same tube for these purposes, but the 5751 is not quite - it has less gain, for one thing.)

These came with my Jadis integrated, and I have always found that amp to offer excellent tone. Like Newbee pointed out, not warm, but not cold or sterile either. I find them to offer a nice balance.

It's nice to hear Zaikesman say they're the best of the current production, that will save me money down the road. Maybe when it comes time to replace them, I'll go for NOS Mullard or Telefunken, but we'll see.

I can also say that their power tubes are pretty bulletproof. 4.5 years and still going strong, on an amp that's on again off again on again all the time by several family members. Of course, NATO bombing the plant probably is the reason for the QA problems of late.