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147 amp with extra 12ax7a gain stage? Ever seen one?

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  • 147 amp with extra 12ax7a gain stage? Ever seen one?

    Recently picked up a 145 in pieces. Complete but the 147 amp has been seriously modded. Discrete AC in and speed control is now controlled by a foot switch hooked directly to the relays. Most unusual , someone has added an extra 12AX7 and a 1/4 inch input. The console load resistor appears now to be a volume control for the 1/4 inch in in but organ level signal is still accessed from pins one and 6. All the other standard leslie pins have been disconnected. Looks to have been done by a competent tech. Anyone else ever seen anything like this?. I'm assuming it was done to be able to use a clonewheel without having to use a preamp pedal.

    Brian

  • #2
    Here are some pics

    Pictures of above
    Attached Files

    Comment


    • #3
      I've heard about this being done, but I've never run across one in person. It's more often a case of the amp being modded for guitar use than organ use.

      I can't really see how the motor speed switching is done, but if it's done by switching 120VAC via a footswitch, that's generally not considered a particularly safe way to do it.

      I can't be 100% sure, but the capacitors used make me think that this modification was done some time ago.
      I'm David. 'Dave' is someone else's name.

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      • #4
        Yes my 147 had this done an extra 12au7 was added to create create a preamp circuit so a guitar and keyboard could be played simultaneously, signal input via two 1/4"sockets, no leslie kit used, very similar setup to briguys description

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        • #5
          This modded 251 is the same idea.Secondary channel has a 1/4" female on a cable that rests against the wall beside the amp when not in use.
          Can use a clone with the box,or the A100.
          12AX7 on secondary can overdrive main channel as well.
          The relay is back to original,that's an old pic.It worked fine,but I always think of the next person....
          A little more iron on these.
          Attached Files
          A100/251 A100/147 A102/222 B2/142 BV/147 BCV/145 M3/145 M102/145 M111/770 L101/760 T222/HL722 M111/770 no B3/C3!

          Comment


          • #6
            I have a 147 with the 12ax7 added , it looks very professional and I have it connected to an A-100. I have it ungrounded and it is hooked to the G terminals. The thing kicks butt at only a 3 setting. I believed the unit was gigged so it was probably used with other instruments. I could take pix or draw schematics if u like

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            • #7
              Originally posted by Frankquip View Post
              I have a 147 with the 12ax7 added , it looks very professional and I have it connected to an A-100. I have it ungrounded and it is hooked to the G terminals. The thing kicks butt at only a 3 setting. I believed the unit was gigged so it was probably used with other instruments. I could take pix or draw schematics if u like
              I would very much like schematics for that modification!
              Current organs: AV, M-3, A-100
              Current Leslies: 22H, 122, 770

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              • #8
                Fortississimo
                I will take pix and sketch a drawing - it may take a few days

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                • #9
                  Attached are the PIX & DrawingClick image for larger version

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ID:	606741
                  I hope this works

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                  Click image for larger version

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ID:	606743 More Pix of 12AX7 Addition to a Leslie 147 Amp

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                  One More PIX Click image for larger version

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ID:	606744Click image for larger version

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                  - - - Updated - - -

                  One More PIX Click image for larger version

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Views:	1
Size:	111.3 KB
ID:	606744Click image for larger version

Name:	IMGP0022.jpg
Views:	1
Size:	111.3 KB
ID:	606744

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                  Not sure how the attaching works Click image for larger version

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ID:	606745
                  Attached Files

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