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12at7 labeled as 12ax7

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  • #1

    12at7 labeled as 12ax7

    I'm doing a cap job on a Traynor YBA2b and came across something a little weird. The pre and PI tubes are labeled 12ax7 from Germany - not E. or W. They have none of the etched European date/manufacturer codes. The weird part is their construction is what I have always considered exclusive to 12at7's - opposing fins... were there ever 12ax7's with this construction? I was under the impression there were not.

    It's late now but I can post pics tomorrow morning. Just a bit of a mystery I'd like to solve for my own curiosity.
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  • #2
    If you mean the plate construction with three holes in one side and a fin in the other: Yes, ECC81, 82 and 83 were all made in this style by RFT and branded Philips, Mullard and so on.

    http://thetubestore.com/rsdecc83.html
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    • #3
      RFT is probably correct (somewhat squat, glass seems a bit delicate, red on the pins at the bottom on the inside of the tube, typically seem pretty good in terms of having low noise). Brimar made a 12AX7 like that (half flange anode--as in just one "wing" on the side) too.

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      • #4
        I think Brimar just rebranded the RFT ones, I've seen them under dozens of brands.
        "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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        • #5
          well, there are Brimar branded tubes not made by them (not unusual for a tube manf.), but AFAIK they did make their own. The ones I'm referring to are these:

          https://www.tubeworld.com/cv4004br.jpg

          sounded good and interesting (to me) when I tried them. Also, Brimar apparently made a version with leads instead of pins. Supposedly built for super long life. The "regular" Brimar 12AX7 is quite nice also IMO.

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          • #6
            PICS

            Here's some pics for reference. They do indeed look like RFT's but the lettering is a bit different.

            http://i27.photobucket.com/albums/c1...3/DSCN0844.jpg

            http://i27.photobucket.com/albums/c1...3/DSCN0843.jpg

            http://i27.photobucket.com/albums/c1...3/DSCN0841.jpg

            Not the greatest pics... I took them very quickly. No codes on these unless the lettered G7... means something?

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            • #7
              yeah RFT. They could come branded all sorts of ways so the print is not necesarily indicative of manufacturer(I have a couple with different brands). The lettering(date code possibly?)--sorry, have no idea if that means anything.

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