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Back to the Dark Ages: Vacuum tubes question!

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  • Back to the Dark Ages: Vacuum tubes question!

    Some years back I stripped out an ancient Allen vacuum tube rack. As I want to find a new home for the tubes, I realize their part numbers have been obscured. They look like 12AX7, or 12AU7 or even 12AT7 types. Can anyone tell me what Allen really used?
    Thanks!
    John
    Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

  • #2
    The standard oscillator tube for Allen organs was the 6SN7. They are often seen on ebay with the Allen brand name printed on the tube.
    Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI, Allen MADC-2110.

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    • #3
      Nope, I have the miniature twin triode types with Allen printed on them and the type # blocked out.
      Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

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      • #4
        Put 12.6V to the heaters and the ages won't be so dark anymore... :)

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        • #5
          LOL!!
          However does anyone know if they were 12AU7, 12AX7, or 12AT7?
          Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

          Comment


          • #6
            You didn't say you had a MODERN tube generator rack! lol I looked through my analog training manuals and after many pages of 6SN7 oscillator diagrams I found one with a 12AU7 tube. (Figure 95 on page 46 of the Analog Service Book.)
            Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI, Allen MADC-2110.

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            • #7
              OK haha, maybe the "dawning" Age then! THANKS!
              It makes sense because most audio circuits that would have used 6SN7 used a 12AU7 in later designs. With the 12 volt filament the power transformer could be designed to be smaller. It takes less copper to step down to (technically) 12.6 volts.
              Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

              Comment


              • #8
                Yes, those 6-Volt filament transformers were big. The Allen I played in high school had four racks of 6SN7 tube chassis (over 400 tubes) and the power contactor for that beast made quite a thud when you turned the organ on. Then there was the day I opened the lid of the console, only to be blinded by the mercury vapor rectifier that powered the four giant Gyrophonic Projector DC motors!
                Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI, Allen MADC-2110.

                Comment


                • Dewey643
                  Dewey643 commented
                  Editing a comment
                  I would have loved to see all those racks of tubes,....and hear that thud when you turned that thing on! I bet it got rather warm in the room where the racks of tubes were.

                • aeolian pat
                  aeolian pat commented
                  Editing a comment
                  I suppose your skeletal x-ray is still visible. Wonder if the organist became sterile?

              • #9
                Did Allen make their own tubes,or were they made by another company that put Allen's logo on them?
                Late 1980's Rodgers Essex 640

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                • #10
                  I don't believe Allen would make their own tubes, it takes a special mfg process. I worked for several electronic firms, they all bought from RCA, GE, Sylvania and the likes. And then put their own name on it like Baldwin organs and Allen organs did. Looks like Allen sand blasted the type number off the tubes, so you'd have to go to them for replacements of the right type! Clever marketing!
                  This is why I posted the question in the first place. I have a stash but was not sure of the type.
                  Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

                  Comment


                  • Dewey643
                    Dewey643 commented
                    Editing a comment
                    Wasn't sure if they(Allen)even done that or not,...make their own tubes,I mean! If not,then they have had to buy tubes from RCA,GE,Sylvania,etc.

                  • MarkS
                    MarkS commented
                    Editing a comment
                    The original 6sn7gtb tubes in our Allen C3, manufactured March 1957, are Sylvania tubes with a green dot of paint on the end. I suspect that the green dot indicated a satisfactory test at the factory.

                    They do warm the keyboards a bit.

                • #11
                  Lowrey rebranded tubes, as well:



                  This was quite common. Even some early transistors got this.

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                  • #12
                    Pretty much every company had their own name put on the tubes. In my Conn 645, which has about 50 tubes in it, all except the power amplifier tubes and one oscillator tube are the originals with the Conn logo on them. The tube type, however, is clearly visible.
                    I think that removing or covering the tube type was a rather extreme policy.
                    Ed Kennedy
                    Current Organ - Conn 645 Theater

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                    • #13
                      edkennedy wrote: "I think that removing or covering the tube type was a rather extreme policy."

                      Perhaps not. I have read that Allen tested every tube before putting it in the generator rack or having one as a spare. That way they could guarantee the performance was within their specs. Tubes, like every other mass-made device, had variances in their construction that affected test results, probably on the usual bell curve. If it kept the local TV repairman from putting in a used tube from his rotating stock, that probably kept the oscillators more stable and with greater longevity. That equals a happy customer.

                      Clearly they would charge more for the tube because of the time to unpack, test and repack the tube. But I think Jerome was as interested in quality as profit.

                      I was amazed at how few tube failures there were on the 1947 Allen I played from 1963 to 1965. In fact I can think of only one tube failure out of the 400+ in the generator racks during those 3 years. All of the other service calls were for tuning or cleaning the slip rings on the Gyro cabinets to eliminate static in the speakers when they were rotating.

                      Even today, fine audio equipment often states that they use matched transistors in the output stages. Obviously someone has to test every one in each incoming batch before qualifying it to be installed in an amp.
                      Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI, Allen MADC-2110.

                      Comment


                      • #14
                        I used to work for electronics firm. My job was Aging tubes in a rack. Then they were marked with a dot of paint. It was considered burn in before instrument calibration . They made RF voltmeters among other things .
                        Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

                        Comment


                        • #15
                          Actually, those Allen tubes were what Allen called "strength coded". That was because the early tube organs didn't have 'leveling' pots to adjust volume of individual oscillators. By the use of tubes with different strengths, one could reasonably 'smooth out' the note=to=note volume differences. The reason I happen to know this is that I worked for an Allen dealer in the early 1970's and there were a LOT of Allen tube organs still around then.

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