Bulletproof current production 12AY7's?

Discussion in 'Shock Brother's DIY Amps' started by 11 Gauge, Feb 11, 2009.

  1. 11 Gauge

    11 Gauge Doctor of Teleocity

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    Hey all -

    Just got a '79 DR that's been properly BF'ed, and the tweaker went the extra step to drop a 12AY7 into V2's slot, which really added some extra cleanliness to the Vibrato channel.

    Problem is the tube is pretty dang sensitive to that 12" right behind it that's rattling the living bejeezus out of it. It was so bad that the previous owner thought it was voice coil rub. I don't want to go to an ext. cab in this case, and all of my other AX7ish bottles have way too much gain, and give the typical somewhat loose and farty feel of a DR (forgive me - I'm used to the bigger BF/SF amps).

    I say current production 12AY7's, but obviously UOS could be considered as well. I'm not really happy with any of the preamp tubes in the amp and will replace them eventually, but I really want the magic back of that 12AY7.
     
  2. ThermionicScott

    ThermionicScott Poster Extraordinaire

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    Does anybody make one besides Electro-Harmonix? That said, EH 12AY7's come stock in the English Muff'n pedal, and I haven't had any trouble with them...

    - Scott
     
  3. sjhusting

    sjhusting Tele-Afflicted

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    Reflektor (EH, Sovtek, TungSol, Mullard ...) is the only current production 12AY7 I know of.

    I've had about a 50% fallout rate on NOS 12AY7/6072s buying from random sellers on eBay (so I don't do it anymore). It's like all the good ones are squirrelled away.

    steven
     
  4. Natstrat79

    Natstrat79 Tele-Meister

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    +1, It's getting harder and harder to find good NOS 12ay7's and Reflektor is the only current production 12ay7.
     
  5. marshman

    marshman Friend of Leo's

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    Wow, I thought it was just me, but I noticed a dearth of NOS 12AY7s, too. Angela wants about $60 for 80's production, I am afraid to ask what they'd want for nice 50's-60's RCAs...

    But I want 'em.

    I think AES has NOS for @ $25 (80's era, I think) or so, at least that's what my last one cost me. I occasionally cruise the hamfests, I'll keep my eyes peeled.
     
  6. Tim Swartz

    Tim Swartz Friend of Leo's

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    Consider a JAN 5751.
     
  7. aunchaki

    aunchaki Friend of Leo's

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    +1
     
  8. EdMax

    EdMax Tele-Meister

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    The most recent batch of EH12AY7's I bought were garbage.
    Something has most certainly gone wrong in production of these tubes.

    12 Pcs, 9 have the same symptom.

    Right out of the box they hum badly, and if you touch one during use it hums even louder! The shields have no effect on the hum.
    They are also extremely microphonic for some odd reason. This is happening in multiple amps.
    The 3 good ones are awesome, but that sure makes them cost a lot.

    I have not been really happy with the NOS purchases either, seems like the GE 6072A/12AY7 is a pretty fussy tube as well.
     
  9. sjhusting

    sjhusting Tele-Afflicted

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    I've solved the problem by buying TAD 12AY7s. They are nothing else than rebranded EHs, but there is at least a selection involved and a guarantee. Unfortunately they cost three times as much as the EH; but I haven't had any problems with them yet.

    I have one good GE 6072 left.

    steven
     
  10. celeste

    celeste Friend of Leo's

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    Since this is A DIY forum, may I suggest that if it is a gain around 40 that you are looking for a 12AV7 or one of it's variants. It is going to want to draw some current, so your are likely going to need to adjust some resistor values to get to it's sweet spot, but it is very available, inexpensive and with a Ra 1/4 of a 12AU7, it sure can drive a tone stack. Try it as a PI, you may never want to use anything else.
     
  11. EdMax

    EdMax Tele-Meister

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    I have a couple dozen NOS 12AV7 & 5965's, various brands, various internal construction types. Box Plates, Wrapped plates Longs & shorts ect

    As far as using them in a V1 position in most amps, these might very well be the WORST tubes I have ever seen for microphonic problems.
    In my 5E3, 29 out of 30 squeel like a pig.

    Though they have similar specs, they were never really intended for audio applications.
    http://tubedata.milbert.com/sheets/127/1/12AV7.pdf

    Millions of these are floating around for 2-3 bucks a piece for a reason, they most commonly used in computers because they held up for extended periods in cut-off mode.
    The gain factor is really not the only thing that matters.
     
  12. FiddlinJim

    FiddlinJim Tele-Holic

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    Well, that's a drag about the EH ones going downhill. I've usually found them to be way quieter than the JAN 12AY7 and 5751's I've had in the same amps.
     
  13. EdMax

    EdMax Tele-Meister

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    I agree,

    Hopeully this is just an isolated problem, up until this last dozen I bought, they have been very good.

    I read someplace there was a shortage of this particular tube and guys were complaining about back orders, I ordered mine 3 weeks ago and ended up sending most of them back. I am still waiting for replacements.

    BTW, returning these is a royal pita, you are almost better off connecting them to an arc welder prior to returning them.

    In a common tester, they show no faults. But if you put them in an amp, the problem is very obvious.
     
  14. Ben Harmless

    Ben Harmless Friend of Leo's

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    I wonder if this is where some of the complaints of noisy operation in the EH tube preamp are originating.

    A shame indeed. I'm frankly a little surprised that JJ doesn't make an AY7.
     
  15. FiddlinJim

    FiddlinJim Tele-Holic

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    I talked with Bob (meester Eurotubes) at the Seattle Vintage Guitar Show a couple of years and I think he said he was trying to make this happen. Not yet, I guess.
     
  16. twangcaster1

    twangcaster1 Friend of Leo's

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    Well, go for it.
     
  17. <jbc>

    <jbc> Tele-Holic

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    In the dark recesses of my mind, the thought occurs that its probably possible to create an AY from an AX given the 'correct' type of abuse.
     
    Last edited: Feb 13, 2009
  18. Mr. Sparkle

    Mr. Sparkle Tele-Afflicted

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    I thought a 5751 was = 12AX7?
     
  19. sjhusting

    sjhusting Tele-Afflicted

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    No. A 7025 is (more or less) the equivalent of a 12ax7. The 5751 has a lower mu (70 instead of 100) and there are a few other differences.

    steven
     
  20. 11 Gauge

    11 Gauge Doctor of Teleocity

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    Having access to all 3 (5751, 7025, 12AY7), spec sheets aside, there is an audible difference.
     
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