12AX7 and 12AX7A Whats the difference

Discussion in 'The Workbench' started by Paramedic006, Mar 28, 2010.

  1. Paramedic006

    Paramedic006 New Member

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    What is the A for in the suffix. Can I run both these in my 2204
     
  2. MartyStrat54

    MartyStrat54 Well-Known Member

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    12AX7: the original version of this tube, released in 1947. This can only be used in parallel filament circuits. This is not a big deal as virtually all audio equipment is of a parallel filament design. In other words, these will work fine in a Marshall.

    12AX7A: This version can be used in series or parallel filament circuits. These usually date to the 1960s and have gray or black plates. Vintage versions of these are about the most sought after tubes of any type today. Sometimes, 12AX7A tubes made for the US Military are labeled 12AX7WA. DO NOT confuse these with current production Sovtek or Chinese crap with the suffix WX, WB, or WC! These are not military tubes and are not NOS tubes at all.

    Also, as tube manufacturing became refined, the 12AX7A became much quieter. So much in fact that a lot of 12AX7A's were labeled 7025's (a very quiet version of the 12AX7).

    So the bottom line is that you can use either of these tubes in your Marshall amp. It's just that an NOS 12AX7A tube is considered to be premium over the 12AX7.
     
  3. MajorNut1967

    MajorNut1967 New Member

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    Oh the "A" in 12AX7A stands for Alpha, because the barium they use on the getters is from Alpha Centauri. And it make the tube have a better magnetic flux.


    :wtf::lol::lol::naughty::hmm::confused:
     
  4. Wilder Amplification

    Wilder Amplification New Member

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    When dealing with current production valves, the suffixes in valve numbers don't mean shit. Valve makers/dealers try to use them to denote some difference in gain factor, vacuum hardness, etc etc. Problem is that every company uses them differently and there's no "standard" as to how they're used.
     
  5. MajorNut1967

    MajorNut1967 New Member

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    So you would plug a 6L6GT into an amp the requires a 6L6GC? Because "The suffixes in valve numbers nowadays don't mean shit." What's the plate & screen spec for a 6L6GC & 6L6GT are they the same? I think you better retract your statement!
     
  6. Wilder Amplification

    Wilder Amplification New Member

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    Show me datasheets for a current production "GC" and "GT". Not original data sheets from back in the day for valves that aren't being made anymore...datasheets for CURRENT PRODUCTION valves.

    Now seeing as how this thread is regarding 12AX7s, my statement is correct. Moreover, the OP is referring to current production stuff.

    Now since you're talking NOS 6L6GT (seeing as how no one even makes a current production 6L6GT) you would be correct...the ratings for a 6L6GC are drastically different than an NOS 6L6GT so as such you would not want to plug a 6L6GT into an amp that runs over 330VDC on the plates...but when you deal with NOS stuff you have to know your prefixes simply because the suffixes actually did denote different valve ratings/specs during the golden age of valves. But for current production stuff, the suffixes are all used differently and they're typically used to denote a tonal difference, different gain factor, vacuum hardness, etc etc.

    One must keep in mind though that not everyone uses NOS valves. Matter of fact, a very small percentage of people do simply due to the cost factor. This doesn't mean that people feel that CP is better than NOS...this simply means that only a small percentage of guitarists can afford to use NOS. And let's face it....once the supply of NOS runs out, it's over/done/gone and you're stuck with CP valves.
     
  7. MajorNut1967

    MajorNut1967 New Member

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    After all that you still haven't answered my question! Whats that tell us?
     
  8. Wilder Amplification

    Wilder Amplification New Member

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    Actually....read it again. I DID answer your question...did you not see where I stated -

    "Now since you're talking NOS 6L6GT (seeing as how no one even makes a current production 6L6GT) you would be correct...the ratings for a 6L6GC are drastically different than an NOS 6L6GT so as such you would not want to plug a 6L6GT into an amp that runs over 330VDC on the plates...but when you deal with NOS stuff you have to know your prefixes simply because the suffixes actually did denote different valve ratings/specs during the golden age of valves. But for current production stuff, the suffixes are all used differently and they're typically used to denote a tonal difference, different gain factor, vacuum hardness, etc etc."

    However...I've just corrected my semantical errors in my original posts so this should be a non-issue.
     
  9. TwinACStacks

    TwinACStacks New Member

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    :) Jeez and here all this time I thought GT meant Groove Tubes and GC meant Guitar Center....


    Here check this out: http://frank.pocnet.net/

    :p:p TWIN
     
  10. Wilder Amplification

    Wilder Amplification New Member

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    If the GT is a PRE-fix it is. ;)
     
  11. TwinACStacks

    TwinACStacks New Member

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    :) Did You check out that Tube Data Sheet Jon? It's pretty handy for reference.

    :):) TWIN
     
  12. Adwex

    Adwex New Member

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    I'm not sure.
    How 'bout a friendly discussion, instead of a fight.
    No need for hostility.
     
  13. core

    core New Member

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    Not sure what the GT is but I do know original 6L6 valves had metal canisters and were developed by RCA. When they went to glass tubes instead they added the G to the end of the model number. From what I read on them it seems it's part of a series G, GA, GB, 5881, 5932, 7027, and the final version 6L6GC.
     
  14. MajorNut1967

    MajorNut1967 New Member

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    LOL great one Twin! Frank's site is one of the best tube data sites there is, nice call.
     
  15. MajorNut1967

    MajorNut1967 New Member

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    Core in the final version (6L6GC) was there quite an increase in Plate & Screen voltage specs? I don't really know the chronology of the 6L6 well. Thanks! I personally think the GT suffix is a more recent marketing of the tube.
     
  16. Paramedic006

    Paramedic006 New Member

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    I have a chance to buy 2 12AX7A USA NOS for about 40 bucks, hence my question. Can I run a standard 12AX7 with these 2 other tubes or would it be better to find a 3rd 12AX7A tube. If so, can someone hook me up, RE Martystrat.
     
  17. Paramedic006

    Paramedic006 New Member

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    Are 2 of these 12AX7A USA tubes worth 35 shipped.
     
  18. Wilder Amplification

    Wilder Amplification New Member

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    Yes, and yes. And if you want a 3rd to go with it, Marty can definitely hook you up.
     
  19. Paramedic006

    Paramedic006 New Member

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    Thanks Jon. I have no knowledge of NOS tubes and I didn't wanna get them in an uninformed way. I read so much on here about NOS vs CP and I'm gonna start small to see if I can tell the difference.
     
  20. MartyStrat54

    MartyStrat54 Well-Known Member

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    If you are buying two 12AX7A's, they will work no problem with a 12AX7.

    What brand are they? Do they come with any test results? What brand of tester?

    $35 for two isn't bad as that would be in the same price range as two current production Tung-Sol's.

    Shoot me a little more info and I can help you out.
     

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