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OT location

Discussion in 'Shock Brother's DIY Amps' started by RollingBender, Jun 19, 2020.

  1. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Are there any special considerations when laying out an amp with the PT at one end of the chassis and the OT at the other end? ...something like this....
    A603DAD7-933B-4A6C-B642-3A8D9E0371A9.jpeg
    ...only with the tubes standing up in between the transformers.
    Any special lead dress or routing that needs to be observed?
     
  2. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    The important thing is to isolate the tubes in a perf-steel cage... and mount a slab of Lucite -- lit from below -- halfway between the transformers. :)

    upload_2020-6-19_20-49-59.jpeg

    upload_2020-6-19_20-59-44.jpeg
     
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  3. Mongo Park

    Mongo Park Tele-Holic

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    I have considered that configuration. However the op transformer is a ways away from the power tubes which it is connected to. Other that that it is great, moving the power tubers closer puts the preamp tubes closer to the power transformer. So I end up with the op transformer between the power tubes and preamp tubes. Which is still a ways away from the power transformer
    When I looked closer you have the preamp tubes closest to the power transformer which I tend to avoid. This sort of thing is always a balancing of compromises.
     
  4. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Ha! That’s the example I’m going for. Designing a cabinetless head with cages around the tubes but in “normal” configuration, I end up with 2 cages.
    As far as the Lucite...I’ll have to add that to the design.

    So...what did Ampeg do to address this issue? Can’t find a decent gut shot of a Portaflex.
     
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  5. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Did some more searching on the google for Portaflex gut shots. All the photos that I found, the board is covering what I want to see and/or the resolution is not good enough to confirm what is going on but it looks like they just twist the primary leads from the OT to B+ and run the secondaries you the output jack with no concerns.
     
  6. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Is there a reason you want the OT far away from the power tubes?
     
  7. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Having the PT and OT at opposite ends would simplify the fabrication of the mesh cage. The way I’m going to build this one, the tubes will be running down the middle of the chassis rather than along the back (point-to-point-ish).
     
  8. elpico

    elpico Tele-Afflicted

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    See also:

    [​IMG]
     
  9. schmee

    schmee Doctor of Teleocity

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    Your setup looks fine. I have found in my experimenting it seldom makes any difference as far as noise goes. Twist the long wire runs though.
     
  10. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Here’s a gut shot of the amp @elpico posted...
    C57431DC-18FF-4B1E-BE1B-D0A7AEBD0569.jpeg
    Looks like the OT leads just lay tight and flat to the chassis.

    Looks like I may be revising my layout after all. The Hiwatt example is not too far of a departure from my build plan.
     
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