Wire an amp with no ground location

Discussion in 'The Projects Forum' started by evilduks, Apr 17, 2014.

  1. evilduks

    Thread Starter New Member

    Apr 17, 2014
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    I am building a boombox into a customized backpack. In this setup would be two 6.5 in speakers, 2 horn mounted tweeters, and hopefully a subwoofer. To power the sub, I need an amp. I am planning to use a 400W amp designed for car use, but everything I've seen says that the amp won't function without the ground. Any advice as to how I could make this work?
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Wouldn't the amp be connected to battery? Battery negative terminal is the "ground".
     
    Last edited: Apr 18, 2014
  3. crutschow

    Expert

    Mar 14, 2008
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    The ground is just the negative or "common" circuit terminal. It has nothing to do with earth ground.
     
  4. BobTPH

    Active Member

    Jun 5, 2013
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    I, personally, would not want to wear that backpack.

    Bob
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Agreed. The battery weight alone would be considerable.
    And I, personally, wouldn't want to be within earshot when the boombox is working :)
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    fortunatly, a "400 watt" car stereo amp is actually a lot less power, a real 400 watt amp would have to have a lot of current to feed it. the only possible problem I can see is that the speaker outputs going to the amp would have to be isolated through a transformer so that the ground problem would be eliminated. car stereo shops should have the transformers.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Speaker terminals are normally isolated from ground. You only need a transformer if one of the speaker wires is connected to ground in an automobile.
     
  8. alfacliff

    Well-Known Member

    Dec 13, 2013
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    and how are they connected in the boom box? isolation would solve many potential problems. auto stereos sometimes "bridge" amplifiers to get more power, then there are no "ground" connections on any speakers.
     
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