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Favorite NOS 12AU7?

Discussion in 'Amps and Cabs' started by dorfmeister, Feb 9, 2008.

  1. dorfmeister

    dorfmeister Member

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    Which ones do you like best?

    Any significant sound differences between American, British, and German NOS 12au7's?
     
  2. Blue Strat

    Blue Strat Member

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    Just curious, what amp are these for?
     
  3. The Keester

    The Keester Member

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    i really like my Mullard NOS 12au7 in my Superbaby
     
  4. GrecoVee

    GrecoVee Member

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    I got a NOS Mullard 12Au7 from Mike and it kicks A$$!!!
     
  5. Sean French

    Sean French Supporting Member

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    I've got a stash of NOS Mullard' that I like.
    I only use them as a reverb driver.They soften the reverb up.
    However,at the moment non of my amps have reverb.
     
  6. Red Planet

    Red Planet Member

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    I use these in V1 of most any Amp, really keep te Amp Cranked and smash it with a Pedal for Distorion.

    I like the Raytheon 5814A's.
     
  7. dorfmeister

    dorfmeister Member

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    Thanks for your responses.

    I plan to get the tubes to put into a Coopersonic Tube Overdrive. It can handle 12ax7, 12at7, or 12au7 tubes. What would you recommend for a tube pedal like this?

    http://www.coopersonic.com/

    [​IMG]
     
  8. Red Planet

    Red Planet Member

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    We it depends on what kind of Gain you like. I'm not familliar with that Pedal so I have no idea how much Gain it has on tap.

    If your going for maximum gain use 12AX7 and then there are steps down from there. I forget which order. I think it goes 12AX7, 5751, 12AT7, 12AY7, then 12AU7 but I might not have that zactly right.

    The thing I like about the 12AU7's is for some reason with my Amp just totally Dimed I get a rich fullness that I just cant seem to get out of a 12AX7 and the volume turned down some (go figure). Then I just step on a pedal and get all the gain and saturation I need.
     
  9. Blue Strat

    Blue Strat Member

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    What have you tried so far? How many tubes does it use? What would you change sonically if you could?
     
  10. Shnook

    Shnook Supporting Member

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    I've got a NOS Mullard 12AU7 in my Gibson Goldtone GA15 RV and it sounds so clean and smooth. Great tube for cleaning up an amp.
     
  11. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Yes there are differences. There are many, many options with 12AU7. Once you've figured out what kind of sonic direction you'd like to head in, please post that more specific question.

    I will give you a tip: if you understand the character of classic 12AX7 tubes, you can roughly translate that character to 12AU7 of similar design/era from the same manufacturer. For instance, long black-plate Raytheon 12AX7A and 12AU7 are similar, sonically, for their gain class. Same goes for long-plate Mullard, Telefunken, Sylvania, etc. This doesn't always hold true, but it is a good guide.

    - Thom
     
  12. dorfmeister

    dorfmeister Member

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    The pedal originally had 6N2PEV tubes in it. It has a switch to be able to use 12ax7's. The previous owner had placed a Groove Tubes 12ax7 and an unlabeled tube which I am guesssing must be another 12ax7 in it.

    The pedal has a very large amount of gain and has some rawness to the tone. I'd like to tame the gain and rawness some but hopefully the pedal won't lose it's character completely. It sounds a bit like a JTM 45 with fuzz kicking in as you raise the gain. I'd like to push it towards more clarity and less gain.

    I am new to switching out tubes and I am wondering if all 12at7's or 12au7's are all pretty much the same size because it seems like a bit of a tight fit for one of the tubes and if I had a bigger tube it might be too large.

    Do I need matched pairs or could I mix and match as long as they tubes are of the same type? Any benefit to that?

    Thanks,

    Bryan
     
  13. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Bryan -

    Sounds as if you're not sure the 12AU7 would be right for your use. It is a drastic drop in gain, and you might rather consider a less drastic drop. First step down from a 12AX7 would be a 5751. It will give you more clarity/less gain. If that is not enough of a drop, I'd try a 12AY7 next. If that is not enough of a gain drop, then I'd go to 12AU7. All these tubes are almost exactly the same physical size.

    Once you've dialed in the type of tube you prefer (5751, or 12AY7, or 12AU7), then you can finesse the tone by choosing one brand over the other.

    Oh, yeah - mixing brands is great fun. No matching is needed. I select by position, and choose, one at a time, the tube that best works for my taste. I always have a mixture of preamp tubes in my amps.

    - thom
     
  14. blackba

    blackba Supporting Member

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    I am going to be in the market for a 12AU7 for a Vox AC50 in a few weeks when the amp comes in.

    I was just going to go with my old standby of RCA or GE as I like their 12AX7's, but now I am thinking a mullard might be better.
     
  15. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Personally, I'd recommend RCA cleartops over Mullard 12AU7. There are lots of Mullard makes, and earlier long-plate versions would be my preference. But they're so very expensive, and are prone to microphonics. The cleartops are more plentiful, and do the job very well.

    - Thom
     
  16. Blue Strat

    Blue Strat Member

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    If the unit has 2 12aX7s in it now, you might want to consider using a mixture of tube types (say, one 12AU7 and one 12AX7) including 5751s, 12AY7s, 12AT7s and 12AU7s.

    Going directly from 2 12AX7s to 12AU7s is going to give you a MAJOR drop in gain which might be too much.

    I suspect that the selection of the right tube types is going to make much more of a difference than particular brands of 12AU7s.

    The bottom line is that you're going to have to try several options. No one here is going to be able to nail it for you on the first shot unless they just get lucky.
     
  17. dorfmeister

    dorfmeister Member

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    Thanks for all the responses. This is giving me quite a bit to think about.

    Martin from Coopersonic says that the tube nearest the input is the first gain stage so it will be most important to the sound.

    If a pedal has two gain stages (2 tubes) what principles might you follow in determining what tube to place in first or second gain stage position? Would you generally want a stronger or weaker tube than the other in the first gain stage? Or would some other principle be at work?
     
  18. Blue Strat

    Blue Strat Member

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    It's really impossible to know this without doing some trials. We can only speculate. Get at least 2 different types (12AY7 and 12AU7 are what I recommended in my PM to you) and try each, one at a time, in each socket.

    This is going to take experimentation, no getting around it.
     
  19. blackba

    blackba Supporting Member

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    Thanks for the recommendation, I will check those out, I think I remember seeing them on KCA's site....:)
     
  20. Ed DeGenaro

    Ed DeGenaro Supporting Member

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    The only AU I love is a GE5814. But that's in a Uni or BiValve so in an OD pedal YMMV.
     

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