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2005 Forester X
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225 Posts
Discussion Starter · #1 ·
I just ordered a Kenwood KSC-SW10 powered compact subwoofer on the many recommendations from the forum. I had assumed that I would have to pass through the firewall and splice the power lead directly to the battery. Then I read the manual:


This is the wiring diagram from the manual. Is Kenwood implying that I can power this thing through one of the accessory circuits in my fuse box? How does one go about doing this, and is this even legit? The max current consumption on the amp is only 8A, so it seems plausible, especially considering that the cable would only be running a couple feet (under driver's seat to fuse box).

Sorry if I sound like a total n00b, but I've never tapped into power in my foz for anything other than the HU. Thanks for the help!
 

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Administrator
2007 Forester Sports XT 4EAT
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40,106 Posts
I installed a Kenwood subwoofer in my '03 X & '07 FSXT. I ran the unswitched battery directly from the battery. Take a look at my audio installation write up, starting here. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Forester X
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Discussion Starter · #3 ·
I installed a Kenwood subwoofer in my '03 X & '07 FSXT. I ran the unswitched battery directly from the battery. Take a look at my audio installation write up, starting here. :wink:
Thanks Bobby...I'd seen your write up and had been planning on following it in my install, but I guess my question now is if a direct line to the battery is really necessary, or if one could just tap into the fuse box, avoiding the hassle of going through the firewall and dressing the cable and connections under the hood. I found an add-a-circuit fuseholder rated to 10A that looks like it'd do the trick, but I'm wary as I've never seen this used before. Feel free to tell me to stop being lazy and to just run the line direct to the battery. :wink:
 

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2007 Forester Sports XT 4EAT
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For most power requirements, a fuse tap would work (I've never used one). For a subwoofer, I'd run to the battery for clean, noise free power, my preference. The Kenwood doesn't draw a lot of power, but the battery wire is a heavy gauge. As long as your fuse tap wire is the same gauge & the circuit you tap into isn't overloaded, you should be good. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Forester X
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225 Posts
Discussion Starter · #5 ·
Thanks for the help Bobby. That makes a lot of sense, and I see your point about picking up some noise going through a fuse tap.

On a related note, what are the 'empty' slots in the fuse panel? Are these blanks or live connections waiting for me to tap? If nothing else, I think I could tap the rear accessory port circuit, as I never use it.

Someone please warn me if I'm at risk for melting wires. I assume that the stock wiring is at least 18AWG, which should carry the 8A I need. If I overload a circuit, a fuse will blow before things get melty, right?
 

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1996 SVX
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473 Posts
For what it's worth: Subaru's OEM subwoofer also uses a 10 Amp fuse, and they tap +12V Battery / Constant from the radio harness.

These subs probably draw half that at most (5A), and most of the time likely even less. I'm sure you'd be OK connecting behind the radio, or at the fuse panel.

Tough to say about the empty slots. Some could have one side with the +12V feed. Theoretically, the wire feeding that should be even larger gauge.

Rather than using an 'add-a-fuse', if you can find an empty slot with live +12V on one side it would probably be better using a male slide-connect terminal (looks like one of the blades on a fuse). Crimp that onto the sub's power wire (in place of the female that wire came with).
 

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2004 Forester 4EAT
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5,462 Posts
Go to the Battery; it just siplifies things. Make sure it is fused though. But, if you can steal power from something like the rear acc port, that would work too, and you would get to use the factory fuse w/o any mods to your box. Just make sure you remove/disconnect the acc port, so noone else uses it later on and causes a problem.
 

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2010 Forester XT 4EAT
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1,118 Posts
If you don't connect the proper gauge power wire, fused or with a circuit breaker, directly through the firewall to the battery (which would actually be easier anyway); :chair:
First, don't ever enter a car stereo competition. Second, good luck with that.:crazy:
 

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1999 Forester
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12 Posts
Im currently installing this and was wondering, where I should put the ground. I'm thinking of running power through the firewall but not sure where the best place to put the ground would be. The instructions say somewhere that is not painted, it looks like other grounds in the car connect to painted areas.
 

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2010 Forester XT
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122 Posts
Yes, it can be done. I've done it previously on my Miata, and my Impreza. That sub is not a power hog, so it will be fine. I would not recommend it for the stronger amplifiers, though.
 

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2018 2.5i Premium CVT
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19,162 Posts
Getting through the firewall is easy. There's a hole covered with a black rubber plug up in behind the brake reservoir. As for the fuse blocks, they just aren't constructed quite the way you'd find the load center in your house wiring, with spare spaces, knockouts, and everything else you'd need to just pop in a new circuit. And as for the accessory sockets, their wiring is terribly flimsy. I wouldn't use them for any sort of heavy, continuous load.

I'd go for the battery.
 

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2005 Forester X
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225 Posts
Discussion Starter · #12 ·
Update: I ran the power direct to the battery. Going through the firewall was remarkably easy. I grounded the unit to a bolt that sits just in front of the parking brake (with the console removed, of course).
 
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