I really hope this works. Stock sub straight to aftermarket sub?

[Cclodbuster2017]

So I have a 2021 KIA Forte GT with the Harmon Kardon stereo in it. It has a stock 6.5" subwoofer in the rear deck. Could I take the wires from the stock subwoofer and run it straight to an 8ohm 12" subwoofer that handles 250 watts rms? Could this mess something up? I dont want to run a cable to the back for an amp to a subwoofer and a line output converter. So would this work fine or no?

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[ThxOne Premium Member]

Is that 6.5" stock sub getting an 8ohm signal and 250w? If so... yes, why not. At that point the only thing that has changed is the cone area. If that stock sub is only getting like 100w then the 12" could sound weak and would be under powered.

 

[1aespinoza 10+ year member]

So would this work fine or no?

To add to ThxOne's comment, KIA Optimas use a 2 Ohms 7" subwoofer. So an 8 Ohms resistance will be high and give you -/+ 1/4 of the wattage.

 

[Cclodbuster2017]

How do you know its a 2ohm 7" woofer?

 

[Cclodbuster2017]

Would this work fine without messing up the cars electronics? I want to put a 12" sub in there. I couldn't start a fire or anything right?

 

[LsGuy]

It's not going to start a fire, I don't know of any recent amp that can't handle an 8 ohm load.

The best I can tell, your amp seems to be total power ~300 watts @ 2 ohm. This is full system power. If they gave the sub 200 watts of the amp, you'll see ~50 watts rms on that sub. Not sure if it'll be audible.

Why are you running an 8 ohm sub? Unusual in the car audio world, is this a sub you took from a home audio system? Is it a 4 ohm DVC wired to 8 ohm? If so, rewiring it to 2 ohm may actually work well for the application.

 

[Cclodbuster2017]

Ok just wondering... where did you get info that the amp handles a 2ohm load and that the amp is 300watts? So I should get a dvc 4ohm sub and wire it to 2ohms? Also which speaker wire to the stock sub is positive and negative? There is a yellow and a purple wire.

 

[Cclodbuster2017]

Will I mess up the stock stereo doing this?

 

[Cclodbuster2017]

I have a KIA Forte not an Optima.

 

[LsGuy]

Yeah it's just info I saw on some forums about newer kias with Harmon systems. It's not a guarantee, but unlikely Harmon is building different amps for each kia model. Your best bet is to dig around for a while and find some exact numbers.

There's also a chance that the radio will shut your sub channel down, possibly the entire audio system if your load isn't correct. Many newer systems kill channels when they don't see the right ohm loads. Definitely don't purchase anything until you know what you are dealing with.

As far as wire colors, while you are researching look for a wiring diagram

 

[1aespinoza 10+ year member]

How do you know its a 2ohm 7" woofer?

I had an "09 Optima with a bad sub. Figured KIAs used this format accross the board. Instead I just replaced the foam surround and ended up with an unused 6.5" and 8" foam surround.

 

[1aespinoza 10+ year member]

where did you get info that the amp handles a 2ohm load

You could use a multimeter to find the sub resistance, but most subs have the resistance stamped on the magnet. For polarity, use a 1.5v battery with two wires. Tap the battery wires to the speaker wires. When the cone jumps out, the positive side of the battery is your speaker positive.

 

[AnthonyO 10+ year member]

The 2021 Kia Forte GT uses Harmon Kardon 320 watt amplifier with a 7" 2ohm subwoofer. A dual 4ohm or single 2ohm subwoofer will be fine off the factory amplifier.