12AX7 Tube Substitutions

Discussion in 'Glowing Bottle Tube Amp Forum' started by Torren61, Aug 3, 2021.

  1. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    Here are some tubes that you can sub for 12AX7 tubes. Some of these can be found at a much cheaper NOS price than 12AX7s and are better. So don't get suicidal about the world running out of tubes just yet.

    12AX7A
    ECC803S, E83CC, E803CC, 6L13
    B759
    12DF7
    7025
    12AD7
    12DT7
    12BZ7
    7729
    6681
    7058
     
  2. Mongo Park

    Mongo Park Tele-Afflicted

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    Thanks for doing the legwork. I like trying new alternate tubes to get off the beaten path on the edge of the weeds.
     
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  3. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    I was surprised to find how cheap some of these NOS tubes are even compared to new JJs. You realize I just screwed myself over by telling you folks about these? lol
     
  4. SnidelyWhiplash

    SnidelyWhiplash Friend of Leo's

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    I have a pair of 6681 that I've had for years. Bought them from a Ebay vendor. Never have used them as of yet. There are tube subtitutions for power tubes, as well. 6v6=7408, 5992.
     
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  5. MickM

    MickM Poster Extraordinaire Platinum Supporter

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    Not to worry, the cat's been out of this bag since the discovery of dirt. Every tube website will list replacements.
     
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  6. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    Well, I never knew it until recently and I may not be the only one. :)
     
  7. Cam-eleon76

    Cam-eleon76 TDPRI Member

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    Another to add to the list:
    Russian 6N2P’s.
    The heater wires are wired a tiny bit differently, but other than that these tubes are virtually identical to 12ax7’s.
     
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  8. pinchegil

    pinchegil Tele-Holic Platinum Supporter

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    So 12 months ago we had no toilet paper, now we have no tubes, I don't believe there is a shortage, Its supply and demand, more people are getting back into Analog, tube stereo amps, vinyl, etc. Heck in the last two years Monoprice had come out with a whole slew of tube headphone amps, stereo amps, guitar amps. This has caused a temporary shortage in new Tubes. NOS tubes might dry up but new tubes won't. From a shooting reference its the same reason we currently have no primers, or .22LR a few years back. Supplies will return, lets not panic buy, leave some for others as well
     
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  9. Engine Swap

    Engine Swap Tele-Afflicted

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    Not worried at all...

    [​IMG]
     
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  10. Mongo Park

    Mongo Park Tele-Afflicted

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    6N2P are about as cheap as it gets, shipping is more than the tubes. I have some but have not gotten around to trying them out. Always good to have a stash for when the mood strikes.
     
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  11. Mongo Park

    Mongo Park Tele-Afflicted

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    I also find tubes themselves fascinating so finding out about a new tube to me is always an enjoyable trip down a rabbit hole of learning. Old tech rocks.
     
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  12. Chipss36

    Chipss36 Tele-Holic

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    Attached Files:

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  13. SnidelyWhiplash

    SnidelyWhiplash Friend of Leo's

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    Damn, that's quite a stash. :)
     
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  14. mrriggs

    mrriggs Tele-Meister

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    You can drop a 6N2P into a circuit designed for a 12AX7 [after switching heater wires] and it'll perform about the same. However, the 6N2P has lower capacitance and lower internal plate resistance than 12AX7 so you can actually get more gain out of it than a 12AX7 if you design the circuit for it. A 6N2P with 270k plate resistor has the same output impedance as a 12AX7 with 100k plate resistor.

    I use them in all my new builds. Bought one hundred 6N2Ps for a little over $100. That was a decade ago and I've barely dented it. Should be set for life.
     
  15. uriah1

    uriah1 Telefied Gold Supporter

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    Avoid the 12AV...even some 12AU...
    Never sounding great..some won't even develop
    enough power to move your speaker...imho
    I prefer military versions...some black plates, some long plates
    triple mica short plates,..
    and definitely the 5751 and 12AY
     
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  16. ChicknPickn

    ChicknPickn Tele-Afflicted

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    I just like lookin' at the picture.
     
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  17. Greggorios

    Greggorios Friend of Leo's Silver Supporter

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  18. jimgchord

    jimgchord Tele-Afflicted

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    5751, 12ay7 sound better in some amps
     
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  19. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    I didn’t include the AU, AT, AV or AY tubes because I was listing tubes that were a direct replacement for 12AX7s meaning you get the same gain. Some of those are lower noise and medical, military or industrial grade. So even if you pay more for them, they should last longer or be quieter.
     
  20. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    The tube list I gave is best used to find American and European NOS 12AX7s for cheaper. Now, it’s true that some of those tubes are going to be REALLY expensive but some can be found for $20 to $40 each. Those will probably outlast and sound better than any current production tube.
     
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