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.
I read some more on these tubes, they claim to be exact Telefunken replicas. It seems the consensus that Ei's have a quality sound but, suffer from erratic microphonics and out-of-the-box failure, but if you get a good one they seem to last.
I went ahead and ordered a tested pair for $29.90 + 14.00 for overnight, why not. I will give my impressions if you want?
Thanks again for the input.
An approach I was able to take successfully on a few occassions - but which may not be practical or available to everyone - was to get 10-20 of these tubes from a local guitar or repair shop that stocked these tubes, and where I could find a guy working there who was understanding of my requirements and would cut me some slack. What I'd request was to be able to take the tubes home for a few hours, and test them all by simply inserting them into the input stage of the phono preamplifier I was using at the time. I would cull the good tubes (for noise and microphonics only), separating them into those that would work in the phonostage, those that would work in less critical stages (amplifier input stage, guitar amps), and those that were rejects. Then as per my prior agreement with the shop guy, I'd take back the rejects in the afternoon for a full refund. This way I was able to be happy without paying a pretesting premium, which I have unfortunately found to be no guarantee of acceptable performance, and even though pretested tubes that don't stack up can be exchanged, you often wind up paying too much in redundant shipping charges on top of the higher initial cost.
P.S. - Trelja, not only haven't I tried the Svet's, I also haven't tried the LPS Sovteks, which I believe Albert Porter prefers among the current crop (though I think he's OK with the EI's as well). So I should really just say that I prefer the EI's to the Teslas, regular Sovteks, and Chinese 12AX7's (and also latter-day Sylvanias), but not imply that I have gathered all the evidence to say the case is totally closed in my mind.
Ei 12ax7ln's sound pretty good. I havent put that many hours of listening in yet, but so far I am impressed. They may be a little dry sounding. However, listening to more material is in order before a final opinion. I am impressed with the seperation. Details seem to abound without any harshness or over exaggeration of the highs. A relatively wide and deep soundstage is present as well.
These particular tubes are the Low Noise model. I can say without reservation that there is almost no "hiss" or any other audible tube noise.
Just a note, Distortion: As far as I know, all the EI 12AX7's will be the same "model" as one another. The 'Low Noise' designation will simply mean that the particular ones you bought have been pretested and culled by the reseller to represent something like the best 10% or 5% of the tube crop tested (along with being priced higher), while the remainder are sold for less without the 'LN' tag.
Zaikesman, hello. Have you had the opportunity to give the Ei KT90s a listen in your amplifier? If you, we are curious to your impressions. Take care, Joe
Joe, this unfortunately didn't work out from a technical standpoint. I'll be updating the original thread.
OK, we'll all be waiting to hear about it, Zaikesman.
Since some of you may still be using this tube, I'll mention that Ram Labs carries them, the pre-war Yugos and as usual very well tested for noise, section matches, etc. I use them in my Music Reference RM10 without a glitch, in that application I just use the standard grade, quiet enough in an amp driver stage, but he also has them suitable for phonostages.