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2359glenn | studio

Discussion in 'Headphone Amps (full-size)' started by silent one, Mar 9, 2012.
  1. L0rdGwyn
    So he includes coaxial SPDIF and AES/EBU XLR inputs by default, his SPDIF to USB converter with the tube master clock is an add-on, an additional board inside the chassis, which I am including.
    leftside likes this.
  2. leftside
    Well those date codes have me stumped. "Z" would imply 1969, but I'm pretty sure they didn't make those tubes that late. Perhaps @gibosi knows. I'm not sure what those numbers represent. Perhaps yours are prior to 1945, and no one seems to properly understand the date codes used back then.

    I also have the Bendix, but haven't pulled those out with the new amp yet. Saving them for the "heavy hitter" bake off sometime next week against the WE 421 and GEC 6AS7G. Been more than happy with the TungSol 7236 the last couple of nights.
    chrisdrop likes this.
  3. gibosi
    The "Z" to the right of the arrow indicates the M-O Valve factory at Hammersmith. I believe that "ZA 4138" is a British inventory number, but I don't have access to to my references at this moment, so can't be sure....
    rnros likes this.
  4. Monsterzero
    I realize that tube recs are hard,with various combos and the amp itself playing a huge part in how a tube may sound. That being said,theyre are universal great tubes that most can agree upon.

    So,does anyone in here have recs on good sounding 12ax7s that do not cost an arm and leg? Im trying to compliment my Telefunken 12au7,which sits in the "driver" seat. According to Rogue Audio the spot where the Tele sits has the most impact on the sound,with an arbitrary 60% figure.

    My initial thought for a pair of 12ax7s was either some clear top RCAs,or Mullards,but im not sure that warm is the way to go. I certainly do not want more Telefunkens in there as that might be too bright. so perhaps something in the middle,with a little sparkle up top,good separation and nice mids.

    Any suggestions? I need a pair.
  5. 2359glenn
    The input is SPDIF and he has a tube USB to SPDIF converter. The newer DAC can be bought with that built in.
    The older one sounds pretty good to me but has the separate USB to SPDIF converter and is only 230 volt.
    leftside likes this.
  6. leftside
    The best Mullards cost an arm and a leg. The RCA are great though. See if you can find the late 40's with D getter and long black plates. These should compliment the Tele's quite nicely. The RCA are definitely on the warmer side. I consider 1960's Mullards also to be on the warmer side. The mid-1950's (the "arm and a leg ones") I find more neutral/revealing with only a hint of warmth. Early Valvo and Amperex are also meant to be very good, but again earliest = "arm and a leg". Brent Jessee gives a great description of these tubes and variations on his site.

    I have some RCA 5751 triple mica, long black plate arriving next week. 5 pack NOS/NIB with RCA 5 pack holder from another guy in Canada. From Brent's site:
    "5751: This version was usually the one made for the US military. These have a lower gain than the 12AX7, but are otherwise totally compatible. Great hi-fi tubes, as the lower gain reduces noise and microphonics. These are all ruggedized and most can withstand a drop on the floor. The internal triode elements are matched as well. The early versions are more sought after as they usually have extra support rods and an extra mica spacer on top of the plate structure ("Triple Mica"), as well as blackplates, all said to contribute to low microphonics. Don't overlook the greyplate versions, they are also excellent tubes, and many of these have the triple mica as well. The GE non-military version is usually the "five star" series, intended for broadcast use. The RCA broadcast type is the "Command" series. Both the RCA and GE broadcast types are scarce, as are any of the triple mica types."

    I also run the Raytheon 5751 windmill getter in the line stage of my preamp, which I like a lot. Not exactly "cheap", but about half the price of some of the other so called "top tier" European tubes.

    I run 1960's Telefunken 12ax7 in the phono stage.

    As you can see from above, the 12ax7 tube rabbit hole is about the deepest tube rabbit hole out there :)
    Last edited: Nov 23, 2019
    Monsterzero likes this.
  7. dminches
    I would get a pair of Mullard CV4004s. They sound great and aren't too warm. Another option would be a pair of 5751s. They have a lower mu so I would make sure they are ok. Here is a nice pair. https://www.ebay.com/itm/2-nos-rayt...777302?hash=item23c65c0f16:g:ng8AAOSwEMxdhc1Q
    Monsterzero likes this.
  8. gibosi
    Checked my references, and yes, "ZA4138" was the old British Government Stores number for the 6J5G / CV1932.

    whirlwind, chrisdrop and leftside like this.
  9. rnros
    Yes, ZA XXXX is the British “Old Store Reference Number” used by the Army prior to the 1944 CV Standard.
    The same tube may have the RAF 10E/XXX number, or both will be used along with the civilian designation.
    In addition to these old store numbers each military branch had their own separate classification number.


    Edit: Hi G, missed your last post, I’ll check your link, thanks.
    Last edited: Nov 23, 2019
    chrisdrop likes this.
  10. mordy
    Hi chrisdrop,
    Did you look carefully on those GEC L63 tubes for other markings? Maybe the boxes have information (if available)?

    Re low priced recommendations for 6080 tubes: RCA 6080 and Sylvania 6080 are inexpensive and good sounding. Re the Bendix graphite plates you can sometimes found graphite plate 6080WB tubes rebranded or made by Raytheon for much less.
    It is easy to spot the graphite plates. I believe that most graphite plate 6080 tubes come with the WB (and perhaps some with the WC) designation.
    Here is a Raytheon graphite slotted plate that sold a couple of weeks ago for $39 (it looks like a Bendix):

    If you look at the pictures the gray graphite plates and ceramic mica spacers and thick metal brackets holding them are very distinctive, but there are regular plate 6080WB tubes that have such type metal brackets as well, so look carefully. The graphite plates come is several different varieties as well. The slotted ones are supposedly the best, but I don't have personal experience with them.
    chrisdrop and leftside like this.
  11. attmci
    Roon, TIDAL, I2s................
  12. leftside
    Looks like @chrisdrop has got himself some very rare pre 1945 GEC L63 tubes. Nice :)
  13. chrisdrop
    I have always said that hard work, diligence, and commitment are critically important ...
    ... and that most often when good things happen to me - it is luck :darthsmile: - which I will gladly take when I can get it!

    @gibosi I hadn't seen that page on pocnet, tx.

    Been listening in the pre-dawn hours already and the present setup is still lovely. Today I will not be rolling. I will however finish soldering some mini-xlr connectors onto my next headphone cable...
  14. whirlwind

    I have tried a few of these rebranded and loved them all. I only use two tube power set-ups and these tubes deliver with authority
    I basically only run two tube set-ups on my GOTL and these are some of my favorite tubes and built to take a licking and keep on ticking.

    I did get a set from @rosgr63 that has pretty much stayed in my GOTL for a long time now....love them with ECC31/32/ Atticus
    These are my favorite 6080 tubes



    Last edited: Nov 24, 2019
    leftside, L0rdGwyn and chrisdrop like this.
  15. Monsterzero
    Anyone have an idea as to who made these?


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