12AX7 question...

Discussion in 'Amp Central Station' started by Jakedog, May 17, 2020.

  1. muchxs

    muchxs Doctor of Teleocity

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    Hah! No "expensive" NOS?

    "Late breakup"?

    In what amp?

    Try a JAN / Sylvania or JAN / GE 5751. You get "late breakup" and it will outlast any "GT, EHX, JJ, etc." You may only need to buy one. It will effectively last forever.

    I got a MST of 'em from an ex- Air force avionics technician.


    The only reason "reissue" 12AX7s are "crazy gainy" is they're crazy inconsistent.
     
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  2. DavidP

    DavidP Friend of Leo's

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    ...oops, you mentioned 'dark sounding' -- in that case, order a JJ ecc83 and might as well throw in a JJ 5751.
    Too bad we are at different ends on the continent (and different countries) -- I'd let you audition some of my 'private stock' NODS 5751s!
     
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  3. 63 vibroverb

    63 vibroverb Tele-Afflicted

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    You may want to consider a 12AT7 in the phase inverter if you have a 12ax7 in there - it will push the power tubes less and clean up a bit. Especially if your amp doesn’t have a master volume.
     
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  4. uriah1

    uriah1 Telefied Gold Supporter

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    I have had tungsols gas out on me and elh bent rods.
    Wimpy rods on a lot.
    I think some of the sovtek probably.
    Military 12ax7wa
    imho
     
  5. Henry Mars

    Henry Mars Tele-Afflicted

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    Most new production tubes are sub par but I find that Tung Sol and JJ's are decent new production tubes for the 12Ax7 types. I find myself replacing new production tubes once a year in the amps that I use a lot. If you pockets are deep go for the NOS tubes like RCA or Sylvania or such.
    These tube issues are likely to drive me back to SS amps assuming I'm sill on this side of the dirt.
     
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  6. muchxs

    muchxs Doctor of Teleocity

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    I often do my research before I post. In this case I looked up good tested 5751 tubes on eBay. And the number is... $30 for a good sections matched JAN 5751, less if it's mismatched. Audiophiles are all goofy about matched sections. It doesn't matter for guitar amps. Mismatched sections can actually be useful. Lookin' for "late breakup"? Use a low buck tube with mismatched sections. Spend less, get what you want.

    Then I took a quick look at JJ prices. Looks like around $15 each, maybe a little less in bulk. Hassle with JJs, they may make it the year you should expect with new production or they may die from the JJ specific crack at the base.

    If you buy two JJs to get one good one you could have bought NOS.


    Lotta musicians are BS'ed by new production. It's pretty much mandatory to re- tube once a year if you use new production and you rely on your gear for your paycheck. Lotta musicians weren't around when you could buy NOS in every little town. There was a time when you could buy tubes almost anywhere. There was always a guy with a big plastic lit up Magnavox or Zenith sign. Walk through his showroom full of Jersey Rococo giant console TVs to the counter in the back. You could buy anything you wanted for tubes, even real Mullards or Telefunkens if you knew enough to ask.

    Lotta musicians are swapping NOS as if the tubes have the pitifully short life expectancy of new production. NOS lasts a lot, lot longer. If I had to choose between good used and new production I'll go for good used. With new production expect to get a year out of 'em or compromise reliability beyond that. I expect high testing used 12AX7s to last decades.

    As always it's prudent to have a few spare tubes and it certainly helps to know when to change 'em.
     
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  7. jman72

    jman72 Tele-Afflicted

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    An old 5751, all the way. I lucked out a few years back and grabbed a big box of NOS tubes that were getting thrown away at a local business. Most of them are totally useless for guitar amps (cool to look at, though), but it had a bunch of Sylvania and GE 5751s in it. Those Sylvania Gold Brand 5751s are amazing- they're all I use in V2 of my 5e3 and my 5f1. The lower gain means I never have early (or hardly ANY) breakup, even in my tweed amps. My buddy built a 5e3 with the exact same specs as mine (transformers, coupling caps, etc.), except he used 12ax7's and his was a growling beast! He couldn't get a clean tone at all. It showed me why some people say a 5e3 isn't very versatile- it isn't with a 12ax7.
     
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  8. PhredE

    PhredE Tele-Holic

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    Consider a NoS military grade (JAN) 12AU7 series tube?
     
  9. gitold

    gitold Poster Extraordinaire

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    Sounds like you may need a 50 watt Origin......: )
     
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  10. DavidP

    DavidP Friend of Leo's

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    ... so I'm sitting here thinking about overhauling my Mission 5E3 that I built back in 2003... Thanks to a good cup of coffee, I recall some people using 5965s and 12AV7s in the first preamp tube socket as good 12AY7 alternative.

    There's a minimal difference in gain factor between the two tube types, and NOS are dirt cheap when you can find them. The story/legend is 5965s were used in a computer environment when tubes were still used, and often in an on/off switching role...

    I did get a couple 5965s but they were microphonic, and the adventure ended there for me. I should probably keep an eye out for some 12AV7s to try again.
     
  11. uriah1

    uriah1 Telefied Gold Supporter

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    I tried a lot of 12AV7 years ago. They do not come close to a 12ay7.
    Just did not sound good , sputtered, or could not even get a signal sometimes.

    Perhaps you could use as rev return or PI in some cases, but, not as V1.
     
  12. ScottJPatrick

    ScottJPatrick Friend of Leo's

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    Definitely a 5751, use them all the time in V1 on my amps, totally confirm what all the other guys have said about them.
     
  13. Bergy

    Bergy Tele-Holic

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  14. Squawker

    Squawker Tele-Meister

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    NOS GE 5751s are not particularly expensive and are great V1 tubes if a regular 12AX7 is too hairy.
     
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  15. uriah1

    uriah1 Telefied Gold Supporter

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    I use blackplate triple mica 5751 in some amps..I got when
    they were not pricey and everyone was looking
    for Long plate 12ax7 mullards and telefunkens.
     
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