Yes, it is really is pleasant to know that you can trust people's opinions here and happily make your tube shopping list based on the consensus of -always polite and respectful- opinions. That kind of pleasantness, that allows for broader opinions and creativity, doesn't just happen magically though, it's obviously because of everyone effort to keep things productive and nice (besides, a troll would be quickly disarmed by the lack of response he'd get here lol, and probably go back to more feisty thread to troll). Many similar threads are much less amusing to browse through lol...
Great, heptodes! I'd had a few written down in my notes for a while, just waiting for investigation, and I believe that Alain person (the guy who had mysteriously tried many new tubes types by himself a year ago, and never gotten ant responses) had tried one or two of them. Funny thing is that at the socket level, all those extra grids are pre-strapped together, so it makes no functional difference compared to a pentode. There are a few more compatible ones out there though, I'll look through what I'd written down.
At any rate, so 6AU6 level apparently? That would already put these at the top or second top tier, which is pretty amazing for random tubes (I don't think we've bumped in to a bad or really mediocre tube for a while now, so we must be doing something right). Look forward to your review after 15-20 burn-in! Btw, any other common brands for these (GE, TS...)?
Edit: There other 7-pin heptodes: 6CS6 and 6BY6. All three tubes families have a ton of special types too, it's always worth getting those.
This is my very first post in this forum, just to concur with Audiofanboy when he says that you can trust people's opinions here, which have been very useful to me. I am not new to high def audio, (in fact, I have a long experience) but have to confess that headphones were not exactly my priority (kind of heresy said here). I do have an excellent pair of vintage Stax electrostatics and some mid range Sennheisers, but I simply was not into it, until I saw some highly positive comments in this forum about the LD MKIII, so I decided to give it a try. Paired in stock form with my relatively modest but splendid-sounding Audio Technica ATH-M50 LE (Anniversary Edition), the result was really astounding.
Since this is a tube rolling thread, I do not want to go off-topic, so let me say that I followed the excellent guide from Dept of Alchemy and replaced the stock GE 5654 tubes with a pair of Voshkod 6J1P-EV gold/platinum grid, NOS military tube ("OTK" rhombus seal) made in the 1980´s in the Voshkod plant, Kaluga city, sent to me from an Ebay seller directly from Moscow at a cost of around $ 18 the pair (including postage). Authentic military stuff, these Russian tubes are clearly extremely well made, solid and sturdy, a little bigger than the stock ones. I wonder what its military use was in the Cold War, I suspect they were made by the thousands so there is still a big stock of NOS tubes you can get at around $ 3 each. Very interesting historical piece, it was obviously not made for commercial purposes but for reliability and ruggedness, so its original cost must have been much higher, no problem for the mighty URSS military budget.
Before I give my humble sonic impressions as a newcomer in this forum of headphone experts, I must say that I am fully aware that a closed back headphone is not the ideal tool to evaluate the LD MKIII. It really needs a good open back HP to be appreciated. I am thinking seriously in the HD 650 or Beyer 800 series. (My wife will kill me if she ever find out the price of these) I do favor a dynamic but natural sound, with precise, not overextended bass and very good soundstage. Any suggestions ?
On the other hand, a good studio monitoring HP like the ATH-M50 LE is like a microscope. Maybe not much soundstage or spatial clues, but It will reveal a lot of detail in the music and has superior bass rendition. My feeling was that the stock GE 5654 tubes are not that bad, as stated in the "rolling guide", in the sense that these tubes are rough and have bad midrange or highs. Perhaps not so delicate and yes, an "upfront" presentation, but overall a nice, balanced, dynamic sound with more than adequate bass, and they improve a lot after about 50 hs, of use. The Voshkods, however, are a different story. With no burn in at all these tubes inmediately revealed themselves as high definition ones. Suddenly, there was more music and more information: powerful and tight bass, extended highs, great midrange and a superior spatial rendition of the performance, very dynamic and revealing. However, after my initial positive impressions, and after listening to a lot of different music ( jazz, rock, classical, latin, etc.) with some VERY demanding HD recordings in both 24/96 and 24/192, going to the limit, the Voshkods showed a kind of "over the edge" quality with some HD music at perhaps the 2k to 4k range resulting in some mild "hardness" in the midrange. The highs were surely very extended, but not as sweet as I would like. I have no doubt that a good burn in will solve some of this problems. It is kind of funny that I am talking about one or two tubes here when the people in this forum have experience with hundreds of them. Well, this is the good thing, as Audiofanboy said, I will trust your advice...