Placing O.T. outside the chassis?

Discussion in 'Amp Central Station' started by italo, Sep 7, 2017.

  1. italo

    italo Tele-Meister

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    Dear TDPRI experts: I´m looking forward to a Single Channel ab763 build but the combo cabinet i got is very shallow and I´m having trouble with interference between the speaker and the transformers. I can clear the power transformer but not the Output transformer.

    The question is: is it OK to screw the OT outside the chassis ??( for example to one side of the cabinet )

    will the longer wire runs affect hum? Should I twist them?

    Thank you all !!!!

    Best regards
     
  2. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    It's hard to answer without a picture. But you for sure do not want to run speaker wires anywhere near AC power or high-voltage wires. The orientation (vs that of the power transformer) is important - again, without seeing the layout it's hard to tell.
     
  3. bparnell57

    bparnell57 Poster Extraordinaire

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    Mounting it internally would be better. External mounting would be fine, but not advisable.

    Plenty of amps did it back in the day. Today you can't because of the B+ on the transformer leads.
     
  4. bparnell57

    bparnell57 Poster Extraordinaire

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    For UL purposes that is.
     
  5. Dacious

    Dacious Poster Extraordinaire

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    You could mount a separate sub chassis on the side or bottom like the Fender Excelsior. Lots of old non-US amps had separate power supplies. Just need to protect/shield the wires to avoid inadvertent electrocution contact.

    Edit: just noticed you said o/t. Plate leads? Mmmmm probably not wise. O/t is relatively small. It could go off to one side without harm, lead dress could be finicky.
     
    Last edited: Sep 7, 2017
  6. italo

    italo Tele-Meister

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    Thanks for your inputs!! I will add some photos to clarify my question
     
  7. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    On early Tweed amps isn't the output transformer mounted on the frame of a field coil speaker and the common way to replace it with a permanent magnet speaker is to mount the OT to the side of the cabinet?
     
  8. italo

    italo Tele-Meister

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    That´s where my idea/question comes from. Is there any harm to have long B+ and plate wires?
     
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