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Installing inline amplifier

Discussion in '2nd Gen. Tacomas (2005-2015)' started by nova4x4, Dec 16, 2019.

  1. Dec 16, 2019 at 7:30 PM
    #1
    nova4x4

    nova4x4 [OP] New Member

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    I'm trying to install an inline amplifier and replace the stock speakers in my 2014 Tacoma (no JBL). Nothing fancy, I just want to improve the basic sound quality with the stock head unit and 4 speakers (no subwoofer). After doing some research in TacomaWorld it seems that the Alpine KTP-445U is a safe bet and should be easy to install since many people have used it successfully.

    I found some really great information about how to make a T-Harness for my installation, but did not find much information about how to power the Alpine KTP-445U. I've read some posts that used the head unit for power and others that created a new power line from the battery. I was wondering if anyone can offer any advice on some basic questions I have:

    (1) Is it necessary to have a separate power line from the battery to run the amp? If so, is it correct to assume it needs to be a 15A line (same as the Alpine fuse)?
    (2) How do I wire the KTP-445U power so that it consumes power only when the radio audio is turned on?

    I am sorry if the answers to these are obvious ... I am a newbe. Thanks for your help!!
     
  2. Dec 18, 2019 at 7:49 AM
    #2
    TacoFergie

    TacoFergie Well-Known Member

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    1. Alpine should have a recommended fuse rating and I believe alpine recommends 10awg wire but if you go with 8awg that would work too.
    2. The remote wire you will wire to the accessory power wire that turns on your headunit.

    I don't know where you plan on mounting it. But look into a "9 wire" cable. This has your accessory power wire as well as 4 wires to run from your headunit to the amp and 4 wires to run from the amp back to your wire harness behind the headunit to connect to the speaker wires so you don't have to fish wires through your doors and such. FYI the factory wiring and the 9 wire is absolutely sufficient for the amount of power you are running. People often think you need larger speaker wire, but 18awg is often fine for door speakers until you run into very high powered systems.

    https://www.sonicelectronix.com/item_116007_Carwires-SW9000-20.html

    EDIT: read through the owners manual and noticed 15a fuse is good but it does not give a recommendation on power wire size which is somewhat understandable.
     
    Last edited: Dec 18, 2019
  3. Dec 18, 2019 at 8:10 AM
    #3
    DG92071

    DG92071 Well-Known Member

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    A amplifiers output is a mathematical equation and a 15 amp fuse doesn't equate to 45x4 but that is neither here nor there. Alpine states that the amplifier can be powered with the stock stereos power wire (I don't know the size of a Tacoma stereos memory fuse, I think it's a 20 amp). Personally I always get amplifier power straight off the battery as it reduces the chance of funky noises and feedback problems. You want a fuse on that amplifiers power wire within the first foot of where it gets its power from. The amp is only on when the stereo puts out 12 volts out of the remote turn on wire which it'll only do when the stereo is on (aftermarket stereo). If you're using the stock Tacoma stereo you'll turn the amplifier on with the trucks accessory +12 volt wire that turns on the stereo. Stock speaker wires are fine. Ground the amplifier within 1 foot of the amplifier and take the paint off of the metal wherever you ground the amplifier at. If you've got an aftermarket stereo ground it where the amplifier is grounded at. If you're using the stock stereo use the Alpine amplifiers high level inputs (speaker wires), an aftermarket stereo will have RCA outputs which is what you'll want to use and preferably run those RCA wires separately from everything else (usually on the floor right next to the transmission hump is a good spot).
     
    Muddinfun likes this.
  4. Dec 20, 2019 at 10:25 AM
    #4
    nova4x4

    nova4x4 [OP] New Member

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    TacoFergie, DG92071, Thank you both for the advice and the detailed information, its very helpful!

    After reviewing some more posts and given your advice I decided to go for a separate line from the battery, and I will make sure the ground connection is as close as possible to the amplifier. I also think I understand why the amplifier fuse is 15A: 45W x 4 channels = 180W and 15A x 12V = 180W so the math works out. Wish me luck with the installation ... ;-)
     
    DG92071 likes this.
  5. Dec 20, 2019 at 10:55 AM
    #5
    DG92071

    DG92071 Well-Known Member

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    I'll be damned, the math does work out. Good call!
     

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