Ok, after spending the last 3-4 days playing around with triodes, I am taking a break from them for a little bit, and letting my amp also take a break from burn-ins.
The CV5311 after 17-18h of burn-in (couldn't force myself to go any further...) showed some very nice characteristics, with some of the best upper end detail I've ever had, only bested in that regard by the Sylvania 8532W, cristal clear highs at any rate. The CV5311 were the least "dry" and "thin" of the triodes I tested, but still ultimately lacked those magical echo-like effects and the liquidity that make "tube realism" what it is and music magical and musical -like with the 6485 or the best pentodes. I am going to choose to just not grade the triodes like all the other tubes I tested, since I -and that's saying a lot- can't truly compare them to pentodes as they just sound so different, and almost feel like they were made for other purposes like monitoring instead of pleasure listening (i.e. extra-detailed and revealing and not necessarily musical). But they do work very well on some music genres and movies, since they make dialogues and sound effects very clear.
On a more general note, all the triodes I tested had some specific traits in common, which is weird, since they were from different countries, brands and types: slightly thin and dry as I've mentioned (mostly "un-wet" not always thin or fleshed-out), treble-oriented -or at least a bit mid-recessed since some had good bass- and quite forward (sounds that were meant to be in the background or just heard as random echoes kind of leap at you from the sidelines almost as loud as the singer or guitars, at first it sounds like extra detail but it just doesn't feel natural because it's all you notice).
So, although I really want to go back to the TS 6485 for few days, I still tested the different heptodes I got in the meantime. No 20 hour burn-in this time, as I don't believe it dramatically changes the sound or the nature of the tube, but merely lets it mature and improve, often massively (after 2-3h, I can virtually always tell if I, both, like a tube's signature, and whether or not it's worth my time, after 20-30h, I can be sure and also see if it's evolved a lot or not), and I just can't add 100s of hours of use on my amp just for the sake of burn-in...
Telefunken 5915/EH900S (6BY6), most likely Sylvania 5915 (think Sylvania JAN 5915) made for the German military -I hadn't paid attention to obvious mil tags on the boxes and eagle symbol on the tubes- and boxed by Telefunken, very nice tubes, open and forward sound, slightly mid-oriented (not treble-oriented at any rate) that somewhat reminds me of the 6GX6/6GY6. Ultimately, I find these to have the same "bring stuff from the background and throw it at your face as loud as the singer" effect that I just don't like that much as it makes music unnatural. If you love the 6GX6, you'd absolutely love those, as they sound similar but much better and less coarse. Less loud by a small margin than my typical tubes and comparable to a 6GX6 in that regard.
Brimar CV4012/5750/6BE6 (yes all three are written on the tube), different and more balanced the Tele/vanias above, less forward but still not as well voiced as my best pentodes. Nice large and deep soundstage, thick and heavy Brimar bass but much better that the other Brimar pentodes I'd tested when back when -would most likely improve quite a bit after burn-in. If you like cavernous, balanced and good separation that sounds natural but still close to you (though not forward like some of the previous tubes), you'd like those. Again, these have a little bit of that 6GX6 flavor that's so difficult to describe. Not sterile sounding at any rate, but more "analog" like I'd described the 6GX6. These are possibly the best of the recent batch, including the triodes, even though (or perhaps because) they don't have the most detail and sound the most "normal".
I actually have two pairs of the last tube type, if anyone's interested, as the Mullard 6BE6W I ordered turned out to be "Mullard" named but Brimar-made CV4012/6BE6W dual labeled. Actually, if anyone's interested in any of the tubes I've recently reviewed and don't seem to be actively using, don't hesitate to PM me, I have tons, and often more than one pair.
Next -and last for now- are my Pinnacle 6AV6/EBC91 that look like no tubes on google, but that can't be that old since their side-getter is an O-getter.
