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Aftermarket sub/amp install in si

Janz3n

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I know this has been covered but I'm kind of lazy and spent 10 minutes trying to find my answer with no luck. Or maybe I did and didn't read enough.

I want more bass. One thing I miss about my golf I just sold is the stereo was so much better and it didn't even have a subwoofer. I want to bypass the factory sub in my si and install a subin a box and amp in my trunk. I was looking at line out converters but read that it's possible with out one. Think i read that all the wiring is under under dash but wasn't sure exactly on how to wire it.

Are there any write ups on this?
 

webby

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So you could unplug the sub at the sub, but leave the oem amp as is. You can tap into one of the rear speakers wires and convert it over to rcas. You can find them on eBay/amazon quite cheap. Then the rcas go to the aftermarket amp. Hook your new sub up to the new amp.

this explains it, but he goes further and replaces all the factory speakers, amp, wiring etc. Just listen to the part about tapping the rear speakers to an amp. If you follow his guide to using an aftermarket amp to power all new speakers, you need an amp that does differential signals. You won’t need that for just running a sub.

 

Janz3n

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id probably be interested in just doing a 5 channel amp as well. didnt really want to replace all the speakers as well but it would sound so much better. my next question and item to research is having an amp with differential balanced inputs necessary. spending $1000 on an amp isnt something i want to do. other 5 channel amps recommended by crutchfeild for the car dont say anything about it and they are around $400-$500.

not sure if this link will work at all. i put together a system for $1000.
 
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fahnix

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id probably be interested in just doing a 5 channel amp as well. didnt really want to replace all the speakers as well but it would sound so much better. my next question and item to research is having an amp with differential balanced inputs necessary. spending $1000 on an amp isnt something i want to do. other 5 channel amps recommended by crutchfeild for the car dont say anything about it and they are around $400-$500.

not sure if this link will work at all. i put together a system for $1000.
If you want to BYPASS the factory amp, you can use whatever you want. If you want to REPLACE the factory amp, you have to use one with differential balanced inputs.
 

fahnix

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Indeed. Most of the reason that I still have the stock audio. The $$ to replace the stock with a differential balanced amp just doesn't seem like $$ well spent to me. Too pricey for me.
 

Janz3n

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I may just look into a loc on the rear speakers with a sub and amp. Or just leave the music off and listen to the exhaust.
 

webby

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Though a line out converter was required?
No...see the link in post 2.
 

Janz3n

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No...see the link in post 2.
Ah. I get it. It helps to read the entire thread. I watched a YouTube video of a guy using a loc on what appears to be a premium stereo. I'm just assuming this by the head unit. Looks like it has no factory subwoofer though.

Either way I'll just buy the rca splice thing.
 

Janz3n

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For fun i disconnected my sub on the weekend. I forgot I did that until today. The factory sub is useless. All it does it rattle the back shelf.
 

Janz3n

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More questions!!

So in that link it says you don't need a loc for the rca because the headunit is not powered since there's a factory amp, I'm assuming that means I would have to attach the rca adapters to the back of the head unit. If I were to use the wiring at the rear speakers I would need a loc since this is after the amp?
 

webby

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There aren’t any rca ports on the factory radio.
 

Janz3n

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There aren’t any rca ports on the factory radio.
I mean wire them to the speaker wires from the head unit. Reason I ask is I watched a YouTube video of this and he used a loc at the rear speaker wires in the back and it was a premium stereo.
 

webby

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You can use a loc at the rears. I know there are others that have done that.
 

fahnix

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I mean wire them to the speaker wires from the head unit. Reason I ask is I watched a YouTube video of this and he used a loc at the rear speaker wires in the back and it was a premium stereo.

You're in the right school of thought if I'm understanding correctly.

Sounds like if it's before the amp, you just need to convert. If it's after the amp, you need to use a LOC.
 

Janz3n

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You're in the right school of thought if I'm understanding correctly.

Sounds like if it's before the amp, you just need to convert. If it's after the amp, you need to use a LOC.
Exactly.

I saw another video of an 8th gen aftermarket head unit install. Guy used 4 rca converters from the adapter harness to the rca inputs in the back of the head unit to retain the factory amp. This is what got me thinking about needing the loc if wiring it in after the amp.

It's pretty expensive just the install one 10inch sub going all new. I recent deactivated Facebook so buying used is a little difficult but having to get a specific amp for the balanced inputs is kind of annoying.
 

Janz3n

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found this on a jl audio site.
"Another benefit of the Differential-Balanced Input design is that it easily accepts low-level and high-level signals from a variety of factory head unit outputs and amplifiers, including single ended “ground referenced” sources, as well as Balanced or Unbalanced “Bridged or BTL” sources. This eliminates the need for Line Output Converters (LOCs) in most installation scenarios."

this makes me think that if i use a loc on the rear speakers then rca to a mono amp to power a sub i dont actually need a differential balanced input amp, which would bring the cost down a bit.
 

webby

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That is correct. You need differential balanced if you’re pulling the oem amp out and using an aftermarket amp to power speakers. If you’re just hooking a new sub up off the rear speakers you can use a cheaper amp (non differential)
 
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