Need help installing subwoofer with amp to oem HU and sound system (2016 FRS)
 

Hey guys,

So I bought a 10 inch alpine subwoofer that is putting out 300w RMS and I plan on using my old mtx monoblock amp that I had from my previous car (the mtx subwoofers were just too big to fit in the trunk of the FRS).

I ordered a line out converter and some metra harnesses off amazon (the 70-1761 and 71-1761), with the hopes of creating a custom plug-n-play harness so I can connect the amp with RCA's and not have to do any splicing.

I am not sure anymore if this will work though. At first I was thinking of taking the rear speaker wires from the head unit and using those for the line out converter. That would, however, disable my rear speakers I believe. The rears are pretty crap anyway, but I was wondering if there is a way of doing this without needing to disable any of the speakers and avoid any wire splicing if possible.

Thanks!

There's a much easier way to do it.

Use your metra harnesses to create a passthrough for the door speaker amp. Conveniently, this amp is located behind the rear seat on the driver's side. Here's a thread that covers how to repin the harnesses and in what order. Unlike that thread, you need to connect the 1760 to the 1761 to allow the signal to still pass to the door amp. Branch off the wires for L+, L-, R+, R-, and remote turn-on and connect these to your sub amp's harness. Don't cut them completely, because you still want the door speakers to work.

Then run power and ground wires for the sub amp, plug your passthrough in between the door amp harness and the door amp, and you're good to go.

I can get pics when I get home.

what he said^

Here is the whole assembly all connected and in place. The silver box is the OEM door amplifier; the black box is the sub amplifier. It's tiny and cute. And powerful: 200w RMS @ 0.5 ohms.

http://i.imgur.com/YHeVWfN.jpg

Here are the two repinned Metra wiring harnesses (white plugs) connected to each other to pass signal through, and the Kicker harness (black plug) bridged off the L+/-, R+/-, (white and grey) and remote turn-on (blue). Other wires coming off the Kicker plug are power, ground, and output going to the sub.

http://i.imgur.com/WaLztZP.jpg

Here is where my assembled harness connects to the OEM harness.

http://i.imgur.com/IDeA2dg.jpg

And here is where it connects to the door amplifier. You can see I also used other Metra harnesses to extend the door amplifier power and ground. I didn't tap off these at all, but I needed to make it longer in order to fit all the extra wiring.

http://i.imgur.com/ywKTnJf.jpg

I'ma say this post should probably be stickied for anyone wanting to do the same with a no wire cut install.

The only part that was cut or otherwise irreversibly modified was the chunk of foam I cut out to make a home for the sub amp. The sub itself is fastened to the back of the seat with industrial Velcro, so it's completely removable in case I need the space. So far I haven't needed the space. The amp is also Velcro'd down.

http://i.imgur.com/YCciLqs.jpg

Honestly this is amazing. Definitely worth a sticky!

My only problem is my sub amp does not have a harness, it requires RCA's. But I guess I can simply connect it to the R and L +/- where your amp harness would go instead.

Thanks a bunch!! I will be doing a very similar install and will post results.

Your FR-S will very likely have RCA outputs on the OEM radio. I would check for that just to be sure. If so, then you only need to tap off the remote turn-on and you can run RCAs from the radio. My BRZ does not, so I had to tap the signal as well.

Scion no longer has pre outs on the back of their radio since they are no longer actually made by pioneer. The older non touch screen units out of the TC were the last ones I believe, maybe the 13/14 frs's, but I'm not certain. My frs is a 2015, pulled out the head unit thinking the same thing but they're just not there. Went with the hi/lo converter route for a few weeks. Four subs later said fuck it and just replaced the deck


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my 13 hu definitely did have sub preouts.

Mine too. You have to turn them on to work though. Buried in the menu, somewhere.

My 16 does not have preouts. I know because I checked. Thus I need the converter. Is it still possible to connect the converter to the setup you described earlier?

Yep. Where I tapped the L+/- and R+/- and fed it to the Kicker harness, just tap those wires and feed them to the line level converter. Then you can connect your RCAs to the converter and be good to go.

Here an adapter that does this. A nice plug and play option.. it says it must plug into the back of the stereo but multiple people have connected it directly to the factory amp in the trunk.

https://www.amazon.com/dp/B00CQUL240...4SGABG0544YK_0