Originally Posted by Acapella11
Brief update after more listening and comparing 6EW6 to CV4015:
Accuracy, transparency and neutrality: CV4015 > 6EW6.
Treble: CV4015 > 6EW6
Mids: CV4015 = 6EW6 just different with 6EW6 more seducing and CV4015 more clean
Bass: 6EW6 = CV4015, the bass is different though, CV4015 is better articulated, defined but the 6EW6 goes deeper, there is more a deep bass vibe to them. In summary, I would say they come out similar.
Noise background: CV4015 better than 6EW6. CV is military grade after all. 6EW6 background improves over the burn in process to a decent level.
Overall, the CV4015 are more audiophile, I would say, also more treble oriented and clean. The 6EW6, more on the warm, seducing side and with more bass extension. CV4015 comes out better after all but they do not compete within the same signature. 6EW6 is a like a higher gain "honey coated" CV4015, if that makes sense ;). Although the CV4015 in summary wins the competition, you would want Norah Jones rather whisper through the 6EW6 into your ears...
Power tube R suffix
This makes sense and I have observed the same with the two points you mentioned.
- Bass and treble are more extended with the 6N6P-IR compared to 6N6P-I.
- The IR's background is pitch black, so yes, micro details are better.
- However, the first thing you notice when listening to the 6N6P-IR is the larger stage, the overall greater spatial arrangement. This is - the - first big difference and immediate impression I had.
Guys, enjoy to see how deep the LD tube rabbit hole is...
Edit: Just on a side note: I am not sure how much of deal a gold grid really is. For example, I have two Voskhods, with and without gold grid - they almost sound identical. However, a third pair from 1975 is a bit better. It has more bass impact compared to either of the other two, but sounds otherwise very similar. I also heard that the 6N6P rather scale with the year of production. So, a 1970 should be way better than a 1990. Maybe gold adds some shine on it but I think year of production seems to have more impact.
I pretty much agree with what you say about the 6EW6 and the comparison with the similar sounding CV4015. A higher gain, nearly as good but with a more in your head soundstage, more punchy bass-ed CV4015. The higher gain and stronger -trade-off for articulation- bass compensate for most faults this tube has compared to the CV4015 and make it an excellent versatile tube imo. It works very well with electronic music btw. While not as black background-ed as my absolutely quiet CV4015, my military non-mil spec 6EW6 are quiet after 10h+ of burn-in, enough not to have to worry about it.
About the -R suffix-ed Russians tubes, where you notice a larger stage (I assume "wider") with the 6N6P-IR, I noticed a "deeper" and "higher" soundstage (I had the "wide" trait covered), so basically a true 3D stage compared to an excellent 2D or pseudo-3D stage I had before. Again, I assume the low noise -R suffix to play a big part in that better and more precise soundstage pattern, both in 6N6P and 6N30P types. I think "gold grids" or gold and platinum grids just kind of come with the best mil spec Russian tubes made in the best times with the best quality control, and are not, in and of themselves, a guarantee of sound quality. I keep reading about how good some 6N6P made in the 60s are supposed to sound and these never have the gold grids trait mentioned; it's the tubes from the 80s and maybe late 70s that have it. The -R suffix-ed tubes seem to naturally have those too. I know my Voskhods 6J1P-EV made 15 years apart and with and without gold grids sound quite different, especially after the loooong burn-in -one improved and the other plunged.
While I'm at it, here's my review/feedback of my GE JAN 6AU6WC, etched 6136, made in 1978, which might have been a bit late. After 15 hours of burn-in, these sound very similar to my GE 8425A, with a bit more bass -not better- and maybe a tiny bit more micro-detail and a tad less gain. BUT, they make music sound like it comes from behind a thin veil, curtain or foam (like foam used to roll-off spiky treble). It reminds me of that muting pedal on pianos that make piano notes sound muffled -keeping their harmonics and detail but muted or sounded a bit "choked" but not muddy either. In this case, you can still hear all the details, but they just don't leap out at you like the 8425A -or CV4015 and GEC CV4014 for that matter- you have to focus to actually hear everything, but it's all there. Overall, a solid A grade tube, that would work well with "Norah Jones" singer/songwriter type music, where intimacy and smoky curtains are preferred to ultra-detailed and analytical tubes -which the 8425A is not as it is just natural. Again, the details are all there, but you have to relax to hear them which I don't always have time to do/feel like doing. Last thing, bass is more muddy than the 8425A, fuller too but not articulate, and that takes the "+" off that A in my book.
Listening to the 8425As again, these are definitely less muffled, more natural, musical and fun (not V-shaped sound fun, just... well, fun). Stuff just falls into place with these, and the bass goes looow -and is articulate- which hadn't struck me the first time around. Definitely my new A+(+) tube. Acapella, if your reference is the CV4015, you would love these!
I'm starting to wonder if GE still had their Schiit together making tubes starting in the mid-70s and worse in the 80s. I had bought some GE JAN 5654W half a year ago, made in 1985 by GE for the military and they really weren't that good; I mean you could tell the quality control had gone down the drain. The construction was nothing like what I read about, not clean or best in class but kind of lackluster (the innards weren't straight and the tube base was all weird looking, even the silk writing was a little off), the tubes crackled and popped when I first tested them, and it got better and quiet after a few minutes -a far cry from what I've been used to with mil-spec tubes, including GEs- and after 25h of burn-in they just didn't make the cut; they weren't unpleasant but just not as detailed or fun or well soundstaged like my other basic 6AK5 tubes in those days. I wonder if my -still excellent- GE JAN 6AU6WC from 1978 aren't a bit like that. They look great (although the getter flash made from their halo getter doesn't actually cover the top part of the tube, but made a donut shaped flash that makes my tubes look like bald monks, I can see the filament light from a small hole above the tube; looks amusing but first signs of QC issues?), sound nice but just aren't as good as the 8425A/6AU6A from the same brand -non JAN- made in 1964, like the QC process gradually went downhill as demand for tubes did -apart from the government that bought lifetime stocks of whichever tubes they still needed, tubes that are now massively on fleebay ;) .
Oh the rabbit hole is deeeeep, and getting deeper by the second! "Off with their tubes" said the Queen... Even though I'm not done testing the 6AU6 family, I'm already on an other tube type, and I have two or three more lined up for investigation. There is no end to this, and the 8425A/6AU6A are already forcing me to revise my grading scale... Who's next?