*helP* transform car system to my computer system

Discussion in 'OT Technology' started by 7urb0, Sep 27, 2003.

  1. 7urb0

    7urb0 Member

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    i have a car system that i would like to convert to my computer system. basically 4 speakers, 2-10" subs, and 2 cheap 400w amps.

    what type of ac/dc converter do i need to make this work?
    and how many amp do i need?

    thanks
     
  2. 04

    04 Guest

    Well you are going to need to build enclosures for the speakers, or otherwise they will sound absolutely terrible.

    You can buy a benchtop power supply from partsexpress.com or use a car battery and run a trickle charger on it constantly.

    As for how many amps the power supply needs to put out, if those amplifiers are class A/B and you want to run them at full power, and their ratings are accurate, you will need around a 120 ampere power supply.
     
  3. dazmanultra

    dazmanultra New Member

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    I'm thinking the two amps aren't 400w rms?
     
  4. 7urb0

    7urb0 Member

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    its about 400w rms total for the 2 amps (cheap amps).
    im not sure if its cheaper to either go w/ a car battery and a charger or just get an ac/dc converter.
    what you guys think?
     
    Last edited: Sep 28, 2003
  5. 04

    04 Guest

    A 120 ampere bench power supply would be VERY expensive, so I would go with the car battery and charger.
     
  6. 7urb0

    7urb0 Member

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    so u mean one of these wouldn't work?
     
  7. 04

    04 Guest

    One of what? :confused:
     
  8. 7urb0

    7urb0 Member

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  9. 04

    04 Guest

    That would work until you turned the volume up... What you MIGHT be able to do is buy something like that, and then use a car battery in combination for those huge peaks. Never heard of something like that being done though.
     
  10. 7urb0

    7urb0 Member

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    thats what i was thinking, hook the amps to a car batt. and then hook the batt. charger to the battery also. that way its being charge while in use. since my car alternator is 70amp and that car batt. charger is 75+amp it shouldn't be a problem keeping the batt. charge right?
     
  11. CraneCamsOU

    CraneCamsOU OT Supporter

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  12. 7urb0

    7urb0 Member

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    hey, nice setup. i pretty much have everything figured out except the power supply. just a question on the converter, does it powers adequetly, or over kill? if i could get away w/ a 30amp i rather do that since the price for 30a and 45a are pretty substantial. thanks
     
  13. CraneCamsOU

    CraneCamsOU OT Supporter

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    Yeah, the 45 amp is more really more than I need. I have it set at 14.4 volts constant so at 45 amps it puts out a steady 648 watts. The biggest load my amps are rated at is only about 450 combined.

    The 30 amp will supply 432 watts at 14.4 volts, which would still probably work for my setup. The reason I went one model up was for expandability and headroom.

    On a side note, I would not recommend buying the pyramid unit previously mentioned. Pyramid is known for severely lacking quality, where as the Bulldog powersupplies are very solid and clean supplies.

    Let me know if you need anything else.

    Chris.
     
  14. 7urb0

    7urb0 Member

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    ok so do you think the 30 amps can push 2 cheapso lanzar vibe model number 218? they are rated at 400watt each.
     
  15. CraneCamsOU

    CraneCamsOU OT Supporter

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    Dont discount the vibe series too much. They can reach their claimed wattage within 5% or so. I'm not familiar with the model numbers, but lets say they are 400 watts RMS each (rms is the only wattage spec you should pay attention to, max rating is next to useless). That means you will need (400 watts + 400 watts) \ 14.4 volts = 55.56 amps.

    55.56 amps is a lot to draw from a 30 amp supply. If you keep the volume above low levels, I would bet the supply would go into protection a lot.

    My recomendations (in order of what I think is most important):
    1) Buy the largest supply you can afford i.e. get as close to 55 amps as you can.

    or

    2) Buy the 30 amp and keep volume below the protection limit of the supply.

    or

    3)Might need to lose one of your amps


    Also, Never use a battery + trickle charger setup. They are more dangerous to have in your bedroom than you may think - not worth the risk if you ask me.

    I hope this helped some.

    Chris.
     
  16. 7urb0

    7urb0 Member

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  17. 04

    04 Guest

    The only problem with that method is that the amplifiers are not 100 percent efficient, and at max draw, you are still looking at over 100 amperes of current.
     
  18. CraneCamsOU

    CraneCamsOU OT Supporter

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    You're right about amp (and converters for that matter) not being 100% efficient, but I dont know where you are getting 100 amp draw from. Maybe I'm overlooking something.

    Anyway, 7urb0, both of those supplies look good, I would recommend the Iota, but both could do the trick.

    Good luck.
     
  19. 04

    04 Guest

    Because assuming each 400 watt amplifier is 100 percent efficient you would get a current draw of ~29 amperes at 13.8 volts. So multiply that by 2 for each amplifier, and you have a draw of ~58 amperes. However, since the amplifier is not 100 percent effcient, you must draw more current than that. Assuming the amplifiers are 60% efficient, that means that if they draw 100 amps of current, they only can output 60 amps of current into the speaker before clipping. So if you multiply 58 amperes for the amplifiers being used by 1/.60, you get ~97 amperes of current being drawn. So I was off by around 3 amperes, but in the real world, its going to vary by quite a bit more than that anyways.

    Unfortunatly thats not even a worst case scenario, if he clips the amplifier, it will draw even more current.

    However, it is unlikely that both amplifiers will be played to the point of clipping anyways, so your total draw will probably be lower. But that is still going to be more than a 40 ampere supply can output no matter what way you try and think about it, it will not be enough. But if he watches the volume, I honestly don't see it being a problem.
     
  20. CraneCamsOU

    CraneCamsOU OT Supporter

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    Ok, I gotcha now.

    btw, Im from Tulsa myself. How old are you?
    I'm 20 and currently at OU.
     

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