Installing monoamp/subs with JBL system

Hey guys, new to working on a Tacoma. I picked up mine with the JBL system, including the JBL woofer/amp combo. I want to upgrade my subs, so I got a couple 10-inch Alpines in a behind-rear-seat box and a basic 2-channel aftermarket amp. It’s not my first install, I’m pretty comfortable with the process.
HOWEVER, I’ve come to learn that the JBL amp is where the faders and crossover are for all the other speakers. So it’s not as simple as disconnecting the JBL amp and plugging mine in with wiring to the head unit.
Has anyone done this sort of an upgrade? How did you do it? I’m trying to avoid replacing all the speakers, and especially the head unit, since I really like the UI and the other speakers aren’t bad.
Any tips on how I should wire an aftermarket sub amp off the JBL system? Thanks!

 

There are a few options, but I went with a Rockford Fosgate DSR-1 install as to get line level RCA outputs to throw at my amp without replacing the head-unit.

If I had to do it again I’d probably swap head units and just go straight to an amp.

 

https://pac-audio.com/products/ap4-ty13

 

the jbl amp also powers all the other speakers.

your best/simplest option is going to be using the jbl amps sub wires as a speaker level input to your new amp. the oem eq will still apply, but it'll get your new subs up and running.

anything else is going to get real expensive real fast in aftermarket adapter modules.

 

So you’re saying branch an inline high/low converter off the existing sub cables? That was my thought too.

Should be able to detach (unbolt) the existing amp, keep it all plugged in, and just mount it somewhere else. If I unplug the sub cables from the JBL sub, do you think I’ll need some sort of impedance or resistance harness? Will it switch off that lead if it doesn’t detect some level of impedance?

 

You know of a solution that won’t cost me $500? I mean at that point I’m already halfway to a pretty decent all-over aftermarket system, especially if I hunt around on Facebook and eBay for some discounts.

 

Theyre not $500 & every stereo shop in San Diego stocks them on the shelf.....
You go to the right shop & they will give you a killer cash price, I paid $280 for mine for my 2024 tacoma with jbl....
Do it right so it's not all hacked-up....
You have to pay to play....

Its $500 on pac website but Im sure its available cheaper.

$329 on Amazon & crutchfield....

Put in the work....
Theres one on eBay for $250 but I have no idea if theres multiple versions....

 

SOLVED: @slater I appreciate the help (not sarcastic). Seriously came close to going your route because I couldn’t figure out why my inline hi/low wasn’t working. Was pulling my hair out, flipping my RCAs and checking all my fuses and moving my ground around to different spots.

Turns out the amp I bought “Used - Like New” off Amazon was fried. I bought an identical one new, hooked all the wiring up just as I had the other, INSTANTLY bumped with that sweet sweet sound.

SOLUTION: I bought a Kicker KISLOC2 inline high/low converter for $18 after talking to the grumpy Geek Squad guy at Best Buy. He recommended this specific one just in case the JBL subwoofer cable required resistance in order to actually transmit signal (some sort of killswitch, I don’t know, I withdrew from my Physics degree when I hit Electromagnetics…).

I left the head unit untouched, and wired my inline into the sub speaker cables (after using a AA battery multimeter to check for +/- of the sub), then that RCA to my amp. Left the other inputs to the JBL amp connected, disconnected the sub itself, and now my new subs work perfectly with the JBL sub disconnected. I’ll unscrew the JBL amp and mount it above my sub box behind the rear seats, and keep the JBL sub somewhere in case I ever decide to sell the truck.

I’ll post photos of my setup so others can follow along if anyone has the same question! Thanks all for the input. @slater I’m sure your way is probably a lot prettier with a lot less electrical tape!

 

i see you've got it figured out, but i'll respond for the future-readers.


you should be able to go direct to the new sub amp, as most have high level inputs that would work perfectly fine.

as far as i know, there is very little 'intelligence' in the jbl amps outputs. i've read of multiple people changing the speakers to numerous different resistances, and it's also popular to do as i'm suggesting, to use the sub output as the input to an aftermarket amp, and i've never seen any mention of any cut-out or issue with the method, yet.

 

@soundman98 yep I’m now cruising around with my aftermarket hooked in and bumping, not sure if the Kicker inline was necessary or if any inline would do but I’ll say it works great! I think I’m about to rewire to a 1/0 gauge for my power and ground because the amp gets a little hot, but the system itself works great! Thanks for the help!

 

Posted photos above. You can see the working product and eventually the finished work after I’ve tucked away all the wires. Please post on here and tag me if you have any questions, I don’t check my email super often but maybe I’ll see it and be able to talk you through how to do this particular job!