Wire up an amp!

Hello all! I just bought the factory non jbl amp harness from Amazon, also bought a knukonceptz 4 gauge amp kit and just put a 10" sub in back seat. Will be buying an a 5 channel amp. Do I need a line out converter to the factory stereo?
Any help would be greatly appreciated.

 

unless your amp has hi-level inputs, then yes, you'll need to convert the factory radio output with a line level converter to RCAs.

 

I was looking at the Kenwood x802 5 channel. Would that work?

 

I truly mean no disrespect Glockman2018, but you really need to look this information up yourself. That way you know everything about the amp(s) in question and when you think of another simple question, you'll have either already read the answer or know exactly where to go to find the answer. If not, you'll be back here asking one question after another and the answers you'll start getting is 'you probably shouldn't be doing the work yourself if you are having to ask questions on basic set-up/car audio knowledge.' Again, I truly mean no disrespect. Just trying to save you some possible/probable embarrassment.

 

Yes - that amp will do just fine.

I have the older 801.5 and it works perfect
This was my setup prior to installing the Dasaita HU.

Also - if you have searched and found it already - take a look here.
Bunch of information in this thread.

 

When installing an aftermarket amp, there are a few things to consider as far as signal inputs go.

The first is your signal source, i.e. factory head unit or aftermarket head unit. Often times with a factory head unit or system, the vehicle manufacturer will have tuned the system to sound good and protect the cheap factory speakers. They'll do things like cut/roll off bass to achieve this. With an aftermarket head unit, you'll have a flat signal output.

The second thing to consider is signal input voltage. In a factory system, either the head unit will have a little amp in it, or in most of our trucks and lots of other vehicles, there's a small external amp under a seat. The thing to think about here is pre-amp and post-amp voltage. Pre-amp means low voltage, post-amp means high voltage (relative to audio stuff). Typically pre-amp means anywhere from 0.5 - 5.0 volts, whereas post-amp means 5.0 volts and above. Back in the day, some/most aftermarket amps couldn't accept "high level" or "speaker level" inputs. This caused the necessity for an additional piece of equipment called a line output converter or "LOC" for short. High level and speaker level are more or less the same thing as saying post amp. Most new aftermarket amps can accept high/speaker level inputs. On some aftermarket amps, they only have RCA inputs but the RCA terminals can accept high or low level inputs. RCA cables are classically thought of as low level because they're typically used in conjunction with aftermarket head units that have low level RCA outputs, but they can also be used for high level. An example of this would be using speaker wire to RCA adapters on the post-amp speaker wires for input on an aftermarket amp.

To help illustrate these concepts/setups:

The most classic/basic factory setup up. The factory head unit has a small built-in amp, say 15 watts per channel, thats only output are post-amp/high/speaker level speaker wires that go directly to the speakers.



In a vehicle with a factory external amp outside the head unit, the head unit sends out a pre-amp/low level signal to the factory amp. While the head unit is sending the signal out over speaker wires rather than RCA cables, the signal is still low level/pre-amp.


When you install an aftermarket head unit, you will have a mix of low level and high level outputs. Aftermarket head units will have a small built in amp just like your basic factory head unit meaning they will have ~4 high level/speaker level outputs via speaker wire, but they will also have 4-6 low level outputs typically via RCA cables. This kind of system can also be found in some factory systems, like in my 2021 non-JBL.

In my truck, the factory head unit directly powers some of the speakers, specifically the dash corners, dash center, and rear tweeters. If you were to tap those wires coming out of the head unit, they would be post-amp. The rest of the speakers on the other hand, i.e. the door woofers, get powered by a factory external amp under the seat. If you were to tap the wires before the amp, they would be low level/pre-amp, and if you tapped them after the amp they would be post-amp/high/speaker level.


Now, with all of this in mind, you can start to think about options for how things will interact if you're mixing factory/aftermarket components. The nice thing is that since most new amps accept high level inputs, a LOC is not a necessity, but there's situations where a "smart" LOC can be useful. By smart I mean an LOC that has more than just the ability to convert high voltage to low voltage. The gold standard right now are the Audiocontrol LOC's. They have a feature called "Accubass" that's essentially proprietary tech in their LOC's that will help fix/correct/restore bass that a factory system/head unit has rolled off/attenuated/removed. If you have an aftermarket head unit, you don't need one because your signal is already flat. If you keep the factory head unit, while not a necessity, many people report that an Audiocontrol LOC with Accubass improves the sound. The nice thing here is that you could start without one and add one later if you want.

When looking at the Kenwood X802-5, it accepts both low level inputs via RCA, or post amp/high/speaker level inputs via a separate input port/wire harness. You've got your low level/RCA inputs over on the far right, and then the speaker level input area is underlined:

There's a little plug that would go into the speaker level input slot with bare wire ends coming off of it to attach to your aftermarket wiring harness(es).
It also mentions in the manual that if you you're using speaker level inputs, the amp has signal sense aka auto turn on:


In your case or for anyone else reading, you'll likely want to tap into the factory signal before the factory amp and use speaker wire to RCA adapters for input into the low level/line in part of the amp for your inputs.