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Thread: What size?

  1. #1
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    What size?

    What size Fuse, Wire, all that good stuff would I need for this amp?

    http://sonicelectronix.com/item_6195...0-2.html#specs

    I'm running 2 10in square Kickers with 450 RMS each and 900 Peak each. Please help!!

  2. #2
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    That's a pretty cool looking amp. I think I'll get that for myself!

    Looks like the amp will have (3) 35amp fuses in it, or on it.. The fuse size depends on your guage wire you're going to run.

    The thicker the wire, the more power it can draw without burning. By adding a fuse to the wire you'll ensure you don't draw more then the wire can handle, and the fuse will blow before the wire will burn and you won't burn your car up.

    To calculate what the amp draw of a wire is, you want to take the wattage draw, and divide that by 120 to determine the ampures.

    That particular amp says it's peak power is 1920 X 1, which calculates to 16 amps drawn max. From there you would typically take consideration of the length of wire you're going to use because the heat dissipates as the cable grows in length. For car stuff you're probably going to use something from 12 - 16 feet in length.

    Based on that, you could run a 10 Gauge wire, 16 feet, with a 20amp fuse on it and probably never blow the fuse, and never burn your wire.

    To figure that out, I used the following resources:
    From - 2.3 What is the best power wire to use? [JSC] (that's IASC info for competition quality wiring and audio):
    http://www.mobileaudio.com/rac-faq/

    Watt to Ampures conversion:
    http://bugclub.org/beginners/math/WattsVoltsAmps.html

  3. #3
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    Quote Originally Posted by lukec View Post
    To calculate what the amp draw of a wire is, you want to take the wattage draw, and divide that by 120 to determine the ampures.
    Thats only true if you are using 120V for power. Replace 120 by whatever voltage you are using if it is not 120V.

    The formula is P = VI where V is voltage, I is current and P is power. So I = P/V.

  4. #4
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    What is my voltage? How do I find it? Sorry, I'm new to all stuff.

  5. #5
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    Unless you have a system that will get power from something other than you battery/alternator, you will be using 12VDC. The key to fuse and wire sizing is that a fuse is sized based on your amp needs but its job is to protect the wire. Generally you take the number of amperes that you system needs to run and multiply by 1.25 (25% over) to get the fuse size. Then you find what wire size can handle that amount of current. If your current is between wire sizes, go to the next size up. This way the fuse will protect the wire. Just remember that going too big on the fuse or wire is not a problem as long as you keep the fuse size to below the wire capability.

    In your case, the manufacturer has already stated you need 3 35A fuses. So you need to wire with wire that will handle at least 35A for each fuse. How long the wire is will impact the size (gauge) of the wire as well. I assume they state 3 separate fuses to keep the wire to a reasonable size. That means you are running 3 separate wires each with a 35A fuse. A run of up to about 10ft would work well with 8 gauge wire. Here are some links to useful information:

    http://www.poweracoustik.com/pa2006/support_main.htm

    http://www.the12volt.com/info/recwirsz.asp

    I do not know your level of experience but you need to carefully look at the section on the poweracoustik site about alternator sizing. This amp will most likely be more than a standard alternator will provide.

    Hope I've helped.

  6. #6
    Maximum Bitrate FusionFanatic's Avatar
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    according to crutchfield's description for that amp:

    Code:
    4-gauge power and ground leads with 150A ANL wafer fuse and holder recommended
    the easiest way to determine the necessary wire/fuse size is to look at the fuses that are on the amplifier itself. in this case, that amplifier has three 35A fuses, so your power and ground wires should be able to safely handle at least 105A (4AWG is the most common wire thickness available that can handle that much current).

    your fuse rating should be higher than what the amplifier will draw, but lower than what the wire can handle. crutchfield "recommends" a 150A fuse because they don't sell any size between 100A and 150A in that fuse type (ANL)

  7. #7
    Maximum Bitrate FusionFanatic's Avatar
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    Quote Originally Posted by lukec View Post
    That particular amp says it's peak power is 1920 X 1, which calculates to 16 amps drawn max
    I'm not sure how you calculated that... but it's very wrong

    you cannot accurately calculate an amplifier's current draw based only on it's peak power output... 1.) peak power levels are often times exaggerated from what the amp can output under normal conditions. 2.) no audio amplifier is 100% efficient, it will ALWAYS draw more power than it puts out.

    that amplifier's specs state a maximum output of 800 watts RMS. It does not appear to be CEA-2006 compliant, so it's probably safe to say that it's power output specs are overrated (but lets keep things simple for now, and assume it can output what it says )

    even if the amplifier was 100% efficient (it's not); at 14.4VDC it would need to draw ~55A to produce 800 watts. since it is a class "AB" amplifier, it is probably 65% efficient at best; at 14.4VDC (65% efficient) it would need to draw at least 85A to produce 800 watts RMS.

    it will draw even more power if it is less efficient. in any case, while it may draw 16A at low volumes, it WILL draw far more than that when it's cranked up.


  8. #8
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    Wow, well I guess ya learn something every day.

    I see crutchfield clearly states "4-gauge power and ground leads with 150A ANL wafer fuse and holder recommended"

    Thanks for correcting that, my solution probably would have caught on fire on burned down the guy's car. Ooooops!

  9. #9
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    Quote Originally Posted by lukec View Post
    my solution probably would have caught on fire on burned down the guy's car. Ooooops!
    as long as it is properly fused, then there is very little fire danger. luckily, your "solution" included a 20A fuse. so it wouldn't have caught on fire, but that fuse would blow when the volume is turned up (it would probably blow the fuse at around 10-15% volume).

    however, if it was not fused then the 10AWG wire would certainly burn up and start a fire if the amplifier tried to pull ~80A from it.

  10. #10
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    So I should go with 4 gauge wire and 150A fuse?

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