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Thread: Stupid question about amps

  1. #1
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    Stupid question about amps

    Ok, I've decided to remove the headunit in my 2001 explorer to mount my lilliput in the double din spot. Now, to go headless I know that an amp is needed. What kind of amp would I need to power my factory speakers? How many channels does it need? (Im just running stereo, no surround or anything). Any recommendations on cheap amps that will take the input of my pc and power the factory speakers? Thanks for answering my stupid question

  2. #2
    Nic
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    if youve got 4 speakersits best to go with a 4 channel amp, you could get away with 2 channels but it means you would most likely need to find one thats 2 ohm stable (assuming your speakers are 4 ohm). For factory speakers your not going to need much power, using a normal head unit you probably get less than 20wRMS per channel, i know my old head unit output about 17wRMS. You probably wont find an amp as low as that, so just look for a low rated amp, check what your speakers are rated at if you can.

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    Top Ramen lgbr's Avatar
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    just make sure the amp uses RCA inputs and that should be all you need. If you want to add a subwoofer later on, get something with a built in crossover.
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  4. #4
    Maximum Bitrate Snootch's Avatar
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    Are you/do you want to add a subwoofer? How much are you looking to spend total? (Keep in mind costs for wiring and fusing) Do you have any problems with used equipment? Does it have the optional MACH system?
    If you just have the basic stereo, get either a used amp through ebay, or a new amp (50w x 4 example):

    http://www.mtx.com/caraudio/products...thunder404.cfm
    MTX Thunder 404 50 watts x 4 channels can be found $140-$180
    A decent little amp you could hook up to your factory 6x8 speakers. If you don't mind losing four ability to fade front/rear, you could hook all 4 speakers up to the front channels, then bridge the other 2 channels to a sub. I would recommend: http://www.edesignaudio.com/miva/merchant2/merchant.mv?
    That is an Elemental Designs 12kx series 12". it is an overstock item, since they are changing to a different design, and moving away from the flat-cone design, to an aluminum cone. that's a great way to snag a great woofer for cheap. Back:

    Front:

    Then you will need wiring, for the amp. I suggest looking up Knukonceptz.com they have good wiring at decent prices. I used all their wiring in my car. This is a link to the wiring kit you would need, the Complete 8 Gauge 4 Channel Amplifier Installation kit:

    http://www.knukonceptz.com/productMa...lation%20Kits#
    You will also need the output of the sound card to be changed into your RCA's. I suggest using headphone to RCA adapters found at Radio Shack.

    http://www.radioshack.com/product.as...5Fid=274%2D369
    I would get a pair of those, one for the front channels, and one for the rear channels. They will allow you to connect your sound card to your amp.

    So, I tried to build a small system that is upgradeable, where you could start with just the amp connected to all 4 of the 6x8 stock speakers,: $150
    The Radio Shack RCA adapters:$10
    The Wiring Kit: $30
    Total: $190
    Then, you could connect all your speakers to the front channels, and bridge the rear channels to a sub:$85 (incl shipping)
    and accound for materials for the box: $50
    an extra $135 for bass.
    THEN, later down thre road, if you wanted your fader back, (or more bass) buy an additional amp dedicated to the subwoofer, or upgrade the stock speakers. I think this would be the best route for you if you are trying to keep the $$ down. Good luck!
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    Snootch, thanks so much for your help! Im slowly starting to understand. A few more questions:

    If I buy the MTX 404 and wire 1 speaker per channel, would it be easier in the future to just buy a mono amp to run a sub? I dont plan on having a sub just yet until I have my carpc running headless. I figure if I wire the speakers to the MTX, it would be simple to just add a mono amp and sub.

    Also, I want to run a single power line from my battery to the rear and then use a power distro box to split it into 2 lines (3 if I add a sub) 1 for my opus, 1 for the 4 channel amp, and 1 for the mono sub in the future. Any recommendations of distro blocks? What gauge wire do I need if I split it? What type of fuse do I need next the battery, and then do I add another between the distro block and amp? Thanks for all your help!

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    Quote Originally Posted by Bob0_o
    Snootch, thanks so much for your help! Im slowly starting to understand. A few more questions:

    If I buy the MTX 404 and wire 1 speaker per channel, would it be easier in the future to just buy a mono amp to run a sub? I dont plan on having a sub just yet until I have my carpc running headless. I figure if I wire the speakers to the MTX, it would be simple to just add a mono amp and sub.
    Yep, a good mono amp is my suggestion. Personally I wouldnt rush with any purchases, first plan out your system and all the components than start going about buying the parts. The reason? While soundcards do provide pretty good control over eq a good amp will still do it better. So, i would suggest getting a mono amp with preamp outs and a 4-channel amp with good crossover/eq control. Preamp out on the mono will let you pass the signal without any distortion to the main speakers -> at the 4-channel amp block the lower frequencies to prevent your speakers from playing the bass parts. No reason to strain your system when you have the sub to do that job, it will give you clearer and less distorted sound overall.

    So do some research before you buy this! Often it's hard to mix and match components after you bought them.

    Also, I want to run a single power line from my battery to the rear and then use a power distro box to split it into 2 lines (3 if I add a sub) 1 for my opus, 1 for the 4 channel amp, and 1 for the mono sub in the future. Any recommendations of distro blocks? What gauge wire do I need if I split it? What type of fuse do I need next the battery, and then do I add another between the distro block and amp? Thanks for all your help!
    Suggestion on a distro box? Only one! Stay away from brand names. While choice of amps/speakers will affect the quality, parts like distro boxes, brand name wires, etc. will not. Find a local electronics store and buy some all your wiring/distro boxes and terminals. As a comparison, i was quoted $3.50Can/feet at a local car audio store for 4AWG power cable... And i got it for $0.75Can/feet at my local electronics store.

    Here is distro box i found for $15Can:


    What gage? Decide on the amps and their wattage, and calculate from there! It all depends how much power you're planning to draw to the amps. You will most likely need some battery terminals (i did buy some brand name ones here, couldnt find anything decent looking otherwise), an inline fuse near the battery:



    You can see the fuse near the battery. Run the main line to the back of your trunk, run it through the distro block and split to all the amps/computer devices you need power to

    Here is a sample wiring diag. i made when i planned my stuff out:


    Last but not least. A VERY good resource for all technical information is: http://www.bcae1.com/

    You can find some flash calculators for the fuses/gage sizes for your setup and much much more.
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    Thanks for the info [iG]. Im not buying anything right away (though I am spending hours searching this board New question though. All the distro blocks I find seem to have 1 4 gauge input (from battery) and then 4 8 gauge outputs. After reading the specs on several amps they say a 4 gauge input is required. How is this solved? Also, some power blocks I see have 2 power input and 4 outputs (example: http://www.cardomain.com/item/STISFPGD4PT) What is second one for? Thanks for taking the time to help

  8. #8
    Maximum Bitrate Snootch's Avatar
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    1- The MTX 404 has built in crossover (to keep the highs out of the bass & vise-versa)

    2- It also has a RCA pass-thru, so later when you decide to add another amp, you don't need to run signal from the source, just plug into the 404.

    3-Usually the reason some amps have 2 of each power connector is so you can connect things like capacitors directly to the amp. It also allows some more wiring flexibility. This also holds true for the extra inputs you saw on the distro blocks. Just more flexibility.

    4- If you KNOW you are going to add another amp down the road, I would run a 4 gauge wire to the rear. This will keep you from having to replace the power wire. Here's a chart on choosing the right power wire size:
    http://www.the12volt.com/info/recwirsz.asp

    5-
    If I buy the MTX 404 and wire 1 speaker per channel, would it be easier in the future to just buy a mono amp to run a sub? I dont plan on having a sub just yet until I have my carpc running headless. I figure if I wire the speakers to the MTX, it would be simple to just add a mono amp and sub.
    Yes, it would, however more $$. I was just trying to point out the expansion possibillities for low $$. You would want a dedicated amp for the bass, but in the interest of saving money, and building up slow, I advocated using the 404 to do everything.

    6- The fuse size at the battery is determined easily- Total up the fuse ratings of the fuses on your amplifier(s) and use an equivelent fuse at the battery. (ex: 40A on 404 + 30A on mono amp= use 70-75A fuse at battery.

    7-
    Any recommendations of distro blocks? What gauge wire do I need if I split it? What type of fuse do I need next the battery, and then do I add another between the distro block and amp? Thanks for all your help!
    I would run 4gauge from the battery back to where the amp(s) are. there, I would add this:
    http://www.knukonceptz.com/productMa...Fuse%20Blocks#
    At $13.00, you can't go wrong. It will provide you with 4 eight gauge outputs, two for your amps, and two more for whatever, plus it's fused. Fuses on the distribution block are not mandatory, but are a good idea, offering more protection. From there, I would run an 8 gauge to each amp. Hope I helped answer some of your questions.
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    Thanks for the reply You guys are awesome. Just a few minor things im still not clear on. 1) If a distro block has 2 power inputs, its not neccessary to use both, correct? I can just connect the single 4 gauge from the battery. 2) Most power blocks Ive seen have 4 gauge in and 8 gauge out. However the specs on the MTX 404 says it requires 4 gauge for its power. Is it ok to just use the 8 gauge output from the block? Thanks again for all the help!

  10. #10
    Maximum Bitrate Snootch's Avatar
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    I think that "requires" just means you can use "up to" 4 gauge. as long as you are giving it 12v, that's all that matters. The multiple inputs on a distro block are there so you can hook the 4 ga from the battery, then go via 4 ga to another block if you wanted to. It just allows for greated flexibility in installation.
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