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Thread: Power setup

  1. #1
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    Power setup

    Hey guys,
    I have 2 Audiobahn 12's that are 4ohm DVC and 1100RMS each with a Rockford Fosgate t20001bd amp powering them both. I have a Kia Optima with a brand new battery, not quite sure of the alternator but do I need any extra batteries to run this? And also, what size capacitor will I need? I am a newbie so any info will help.

  2. #2
    Maximum Bitrate Dragonknell911's Avatar
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    Well supposedly that amp makes 2000 watts rms at one ohm, with max output usually being 2x that. Meaning for an instant it could be making 4000 watts, or (4000/12) be pulling 333 amps.

    Now obviously it is'nt going to do that, but I would still suggest you upgrade your alternator. I've heard of people having problems powering that amp even with a 200 amp alternator.

    When you say you just got a new battery, is that a new stock battery or an aftermarket one?

    If a stock one, I would definitly suggest an aftermarket one, I have a civic so I can't really do more than suggest a good battery for you, beyond something like an optima yellow top.

    As far as capcitors, i'm not sure what size would be best, hopefully somoene else can chime in, but you will definitely need one.

    Also, make sure to upgrade your ground from your alternator, from your battery, and the power wire between your alternator and your battery.

    That setup should sound sweet though, enjoy
    REBUILDING!!

  3. #3
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    How do you have the speakers run? If all four coils are in parallel then you're looking at 1Ohm which will suck a TON of power. If you're talking about coils in parallel, speakers in series, then you're talking 4Ohms and about 750W or so. My suggestion, bigger alternator. The alternator charges your battery so its more important in this type of system, but a better battery, a deep cycle, would be a great idea too. As far as caps go, for a big system more is better.

  4. #4
    Maximum Bitrate Dragonknell911's Avatar
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    Well seeing as those subs are 1.1k rms a piece, i'll bet he was going to run them in parallel and make one ohm, to get about 1k to each of them. Which would be awesome and make the amp a wee-bit power hungry, and hot and moody.

    btw what size cap to get will really depend on your setup. such as,
    what size alternator you get (if you choose to upgrade)
    what size battery type of battery you get (also if you choose to upgrade)
    how much power all of your stock electrical components pull,
    and what size wires you run,
    as well as your driving habits.
    REBUILDING!!

  5. #5
    Maximum Bitrate Dragonknell911's Avatar
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    Also caps are used for two main reasons:

    one, you observe a drop in voltage while driving i.e. lights dim, when bass hits or

    two, you wish to increase the life of your amp by stabilizing the power source it recieves.

    If you are noticing that your lights dim, then the power to your amp is most likely not stable (constant voltage).

    But its really up to you. If your lights dimming and your amp dealing with harsh conditions does'nt bother you, then don't waste the money.
    REBUILDING!!

  6. #6
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    Quote Originally Posted by Dragonknell911 View Post
    Also caps are used for two main reasons:

    one, you observe a drop in voltage while driving i.e. lights dim, when bass hits or

    two, you wish to increase the life of your amp by stabilizing the power source it recieves.

    If you are noticing that your lights dim, then the power to your amp is most likely not stable (constant voltage).

    But its really up to you. If your lights dimming and your amp dealing with harsh conditions does'nt bother you, then don't waste the money.
    Actually in most cases where lights are dimming, a cap is like putting a bandaid on a bigger electrical problem and should not be considered a solution. Many times the cap will add load to the electrical system. The big 3 is the best light dimming solution.

    Also don't amps have caps inside them to stabilize power.

    Do this and forget the cap.

  7. #7
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    Amps do have caps inside of them and they're probably used to stabailze power. But, the manufacturer assumes you have a stable power source in the first place. If you give the amp a source with a relatively large AC component (2V P-P), I don't care how good your amp is, it won't be able to stabalize that. A large external capacitor will apply an initial load to the system, technically, it will always be a load on the system. But, once the cap is charged, it will discharge quickly to help stabalize some of he AC components on your power line.

    All in all, if you want to do it right, definately upgrade your car's wiring. Also get a cap, 1-5F should be fine. Get a better alternator, get a better battery. It's just like an engine, you can put a blower on it, but you'll need to buy a billion other things to keep it running!

  8. #8
    Maximum Bitrate Dragonknell911's Avatar
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    Amps do have caps inside of them and they're probably used to stabailze power. But, the manufacturer assumes you have a stable power source in the first place. If you give the amp a source with a relatively large AC component (2V P-P), I don't care how good your amp is, it won't be able to stabalize that. A large external capacitor will apply an initial load to the system, technically, it will always be a load on the system. But, once the cap is charged, it will discharge quickly to help stabalize some of he AC components on your power line.

    All in all, if you want to do it right, definately upgrade your car's wiring. Also get a cap, 1-5F should be fine. Get a better alternator, get a better battery. It's just like an engine, you can put a blower on it, but you'll need to buy a billion other things to keep it running!
    I'm going to assume the 'AC' was a typo, and that you meant DC
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  9. #9
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    Quote Originally Posted by Dragonknell911 View Post
    I'm going to assume the 'AC' was a typo, and that you meant DC
    No, I meant AC. Any power signal can be split into an AC and DC component. Granted, in a car the DC is at least an order of magnitude greater than the AC component, but with a large system like this the AC component will become larger due to quick bursts of current needed with that amp. The point of caps, in this situation, is to get rid of the AC component by charging them when the system isn't drawing full power and discharging when the power is really needed.

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