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Fetish grade 5751 preamp tubes (12AX7 substitute).

Discussion in 'For Sale: Parts, Strings, and Accessories' started by kurosawa, Nov 1, 2013.

  1. Every scrap of bass equipment I own is up for grabs to pay for a divorce lawyer. The kids told me all at once in a jumble in the car on April 18, 2011, that they wanted to stay with me and not her (they'd never spoken of it with each other--all three were thinking the same thing) and ever since, I've had only one goal, to make their simple wish a reality.

    The latest installment in this ongoing sale is, very simply, my sound, contained in two obscure perfect tubes, although they've been parked awaiting finalization of a rig that's never going to happen. There were a few other decent tubes that turned up in my quest, of which three remain. They are also up for grabs.

    I'll post pics of the tubes in reply to this first post, but for now, I'll just post an article I wrote at least 10, maybe 15 years ago summarizing the quest that turned up these tubes. It was published a now-defunct publication (it seems the publishing company is no more, at least not on the Web). A post that served as the draft remains on the Tube Asylum.

    These tubes are only for the obsessive who have every part of their rig already figured out except the tubes. They don't fix flaws in a rig; far from it--they'll show them up in excruciating detail. And they're gonna cost. Anyway, I've had far too little sleep, so I must crash before work. I have time now only to post my article.

    Attached Files:


    The perfect Sylvania JHS-5751 tubes (listed as item 1 in the test). I have one box missing a flap that came with one, showing a packing date of December 1959. Here are phone photos taken without and with flash to help you make out the gold imprints, much faded from swapping them hot in and out of the Grand Prix during A/B testing. These tested 1500/1500 and 1500/1500 micromhos on my B+K 650 tube tester, a perfect match. 5751 tubes test new at 1200. These almost have the transconductance of 12AX7 tubes, which test new at 1600.

    Attached Files:

  3. Here, left to right, is:

    1. A pair of GE triple-mica black plate 5751 tubes (listed as item #2 in the test). They tested 1400/1100 and 1400/1100 micromhos (identically unbalanced). The code 188-5 is the Owensboro KY plant that GE bought from Kentucky Radio; 58-17 would be the 17th week of 1958. I don't know what 57-42 means unless it's another date code.

    2. Another Sylvania JHS-5751 testing at 1050/1300 micromhos.

    If you know what the stages of your tubes do, you'll know if these will work well for you. These all sounded great to my ear in the single-tube test preamp.

    12AX7 types are twin triodes, that is, two tubes in one envelope. If each stage is used to perform a different task, it little matters if they're balanced. I would think that any of these three tubes would work great in a single-tube preamp.

    Balanced stages can be critical in a 12AT7 used as a phase inverter (I have some Hungarian Tungsram 12AT7 tubes listed, too).

    I'd guess balance between left-right stages across the pair is important to stereo hi-fi hobbyists. Maybe between stages within the tube, too, depending.

    Attached Files:

  4. RHFusillo

    RHFusillo Supporting Member

    Mar 20, 2000
    Phoenix, AZ
    I read your article, and started using 5751's instead of 12AX7's as a result.

    Can you post prices, please?

    Best wishes for your legal fight.
  5. Thanks for forcing me to get off my butt and figure out pricing!

    $75 each for the two best. I've seen cosmetically perfect ones that are 5% matched with standard Gm go for 300/pr. so in keeping with my other tube pricing, half that is good.

    The GE and the average Sylvania will be $30 each. The prices are all over the place but I think again that's roughly half of an average.

    If you were to buy all 3 Sylvanias, you might want to keep the perfect pair for recording and use the one you have and this average one for live work.

    I had a mint triple-mica gray plate Gold Brand with gold pins and it wasn't nearly as good as the black plates.

    If the black plate triple-mica Sylvania is your sound, why mess with the rest?

    My PayPal is kkurosawa@gmail.com

    Shipping is $5.90 for Priority Mail, let me know if you want insurance, but that hasn't proved necessary for preamp tubes in the small flat rate box so far.
  6. esoxhntr

    esoxhntr Supporting Member

    Jun 21, 2007
    Markham, Ontario
    These would be awesome for a Genz STL 900. Just sayin'...
  7. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

    Nov 23, 2011
    Denver, Colorado
    I'll take one of those black plates. Sending $ now.
  8. Got it, thanks!
  9. To repeat some info I sent in PM yesterday:

    Q: Which tube is still available, and your recommendation, if any?

    A: One of the perfect ones is sold, one is left. You know that's my personal pick over any other. There's an "average" Sylvania left, and the difference between it and the perfect one probably can't be heard in live playing.

    Now if you're a flatwound player, you may have preferred the Hungarian Tungsram ECC83. I had 4 and sold them cheap ($20 each, they go for $60). That is a brash tube, nowhere near the clarity of the great Sylvania 5751, but an aggressive rockin' tube.

    I have a theory the GE tubes are perfect for slapping, but I'm not a slapper.

    ...and later, I added my advice to go to eBay for NOS Tunsgram; that Eastern European eBay vendors have been good to me, but avoid all shipped from Asia (I don't know for sure but like, I noticed that all of a sudden a zillion Chinese in Hong Kong are offering rare NOS tubes of the same type, like they found a hidden stash, NO WAY).

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