Want to know how to hook up an amp and sub to a stock stereo?
Wiring up an amplifier to a stock radio is something that many of our customers do themselves. With the proper parts and correct wiring, this can be an easy way to improve your factory stereo system.
The first thing you will need, if you don’t already have it, is a line output converter. We carry the PAC Audio LP7-2. This is what is going to feed signal into your amplifier. Factory radios don’t have pre amp outputs, this adapter will convert factory speaker wire into a preamp output. These line output converters, also known as hi to low level converters, are typically wired into the rear speaker wires of a vehicle. This will provide audio signal to your amp. It is very important to get the phase of the wiring correct. If you just tap into a pair of speaker wires and happen to get some sound, you may not necessarily have positive and negative correct. If you were to get the right rear speaker positive and negative correct, but the left rear speaker positive and negative reversed, you will have effectively canceled out your bass frequencies.
Check the phase
The factory speaker wires will not be labeled and will not be marked like typical aftermarket wiring harnesses. You will need a multimeter and a double AA battery with some speaker wire hooked up to it in order to test for for speaker wires and the phase. To make your speaker wire tester, simply take some speaker wire and electrical tape the positive wire to the positive post and the negative wire to the negative end of the battery. Speaker wires tend to be grouped together, so look for what may be pairs to start testing. You will want to make sure you are not sending power to any wires other than speaker wires, so that is where your multimeter comes in handy.
In most cases, you will want to wire the line output converter in behind the stereo. This is a good idea if you ever plan on changing the stereo as your RCAs will already be ran. After removing the radio, using your meter, check for power, ground and accessory wires. Once you know what is not speaker wires, you can start testing pairs of wires.
Strip back a little bit of the wire and hook each end of the battery tester up to a pair of wires. If you have a pair of speaker wires, you will hear the speaker popping or scratching. Once you hear sound, you need someone else to actually look at the speaker. If the speaker is moving in and out, you have positive and negative correct. If the speaker is sucking back in, you have positive and negative reversed.
Once you have determined the proper speaker wires for the rear speakers, you can tap into them and hook them up to the line output converter.
How to connect the remote turn on lead
Now that you have your speaker wires figured out, we can move on to the remote turn on lead. If you use the PAC LP7-2 with signal sensing remote turn on, the line output convertor itself will give you a remote turn on lead. This is not a standard feature of all line output convertors, so depending on which one you use, you may still need to find an accessory power source in the vehicle. If you were testing all of your wires earlier with a multimeter, you should know which wire is a switched power source. That would be the proper place to wire in the remote turn on lead. You do not want the amp wired up to constant power as this will drain your car battery.
Buy a dedicated bass knob
One down side to wiring in an amplifier to a stock radio is that most stock stereos are self adjusting, meaning as you turn the volume up on the stereo, internally the stereo is usually keeping the bass level and the same in comparison to other frequencies. They do this to prevent you from blowing up the stock speakers. This can be pretty frustrating as it means your subwoofer level may stay the same regardless of you turning up the volume knob on the stereo.
One way around this is to also wire in a subwoofer control knob. I particularly like the JL Audio CL-RLC as it is not only a subwoofer control knob, but also a line driver. Line drivers boost the signal from the stereo which can give you a lot more output. Now that you have your signal and remote turn on figured out, the rest is a pretty standard amp installation.
If you are adding an amp and sub to an already amplified factory system, you need to wire your amp in a little differently. If you have a premium factory radio, that has it’s own amplifier, check to see if there is a factory subwoofer. If you are adding an amp and sub to a factory premium sound system with it’s own stock subwoofer, you must get your signal for the line output converter from that subwoofer. If you do not, you will not get any bass output. The reason for this is the stock amplifier will be crossed over at a certain frequency.
When there is a stock amplifier in a car, it is filtering what frequencies get played through what speakers. If this is the case and you wire in your line output converter to the rear door speakers, you may only be getting frequencies of 80 hz and up, not exactly what you’re looking for when it comes to bass. So be certain you get your signal from the stock subwoofer if your vehicle comes equipped with one.
Another problem you may encounter when wiring an amp and sub into a premium factory sound system is the signal level may be too high or too low. You may have to get your signal before or after the amplifier; every car is different and you just need to try it to really see what will work best for your vehicle and application.
Adding an amp and subwoofer to a stock radio can be the easiest way to improve your stereo system in your car, if you do it correctly.
109 Comments
Hi annie i have 2018 JGC with alpine stock amp .. i used jl loc22 added my t1500 rockford amp and 2 sundown sa v2 1000 watts rms each … also swapped all door speakers to infinity ref still using fact amp soumds clean … ? Is sub box misses upper bass notes i tapped into factory subwores for high level into jl loc … should i have tapped rear door speakers insted since they supposedly get full signal from fact dsp .. those doors i replaced with 6.5 imfinity
Hi Rich, I would recommend using the PAC pre-amp adapter to get a clean signal from the stock head unit in this case. Either the AP4-CH41R2 if you plan on eventually amplifying the interiors or the APSUB-CH41 if you’re doing sub only. This will let you get signal before the stock amp before it’s been processed and crossed over so you can set the frequency to exactly what you want it to be on your aftermarket amp.
Otherwise, the stock sub would be where we would recommend grabbing signal if you’re going to use a LOC because in my experience in most amplified Jeeps (at least in the Wrangler’s) there is no full range signal to the rears, it’s still crossed over. You could do a frequency sweep channel by channel to be sure or if you have a few test tracks with a few different frequencies to try like 40 Hz, 60 Hz, 80 Hz, 120 Hz etc. Maybe it’s a better range in the rear speakers in the Grand Cherokee’s than what we’ve seen in the Wranglers, but my guess is the rears are still crossed over and may be lacking the low end bass notes. I hope that helps!
hi there. i have installed amp and sub to factory sub using line out converter. i am having trouble with the bass. i am only getting good bass when i balance all my speakers to either left or right. but when balance is even, i don’t get any bass. and i have tapped in the rear speakers.
any suggestion and help will be much appreciated.
Hi Paras, that means you’ve got one of your positives and negatives mixed up when you tapped your speaker signal from the car. I hope that helps!
If I connect and amp for a subwoofer to the stock sub speaker wires. Will my new subwoofer be limited to the same range as my stock one?
Yes – same frequency range.
Hello Annie,
1. Sure wish we had you guys nearby. In about a 9-hour drive, I could make it. But alas, I’m limited to one local audio shop and big box store installation. So I had the remote starter done by local shop and the audio done by a big box company.
2. So, I have a 2016 Toyota 4Runner. It has the Entune system — non-JBL and no subwoofer but with eight speakers — but it sounded pretty disappointing. So I had the store last week install a 600w kicker four channel amp, all new kicker KS speakers everywhere except the dash and some dynamat in the front doors.
Stereo sounds so much better that it is actually kind of amazing to me. Llots of bass despite no subwoofer and pretty impressive highs, too. Lots of volume now, which was really weak before.
So all’s well, but i noticed the left/right channels were reversed when I used the balance controls on the head unit. So I took it back — they swapped the component cables on the amp under the seat and all is well, EXCEPT, now the truck acts like the key is in the accessory position all the time. The radio stays on, as does the clock and the 12v ports. Even if I remove the keys and open/close the doors, it all stays on.
Switched back the RCA cables and it stops and returns to normal. Installer thinks a remote turn on signal is feeding back from the amp. I’m set to take it back next Wednesday but if you could offer your thoughts on what’s going on there, I’d appreciate it and would love to have a sound theory to tell the installer.
Thank you!
Help!
Hi Matt,
Sorry I could not reply sooner – interesting story there. I’m curious to find out what they did. Most amplifiers have a signal sensing turn on option these days so the idea is it doesn’t turn the amp on until it senses audio signal coming through the speakers. I guess in this case they used a separate line output converter since you mentioned they used RCA cables. I don’t see how the amp could have been back-feeding and keeping the accessory on because that’s how the amp knows to turn on (if they didn’t use a signal sensing turn on). Perhaps a faulty line output converter? Let me know what happened.
Hi Annie, you sure have a pretty good knowledge of stereo’s…good on you.
I’m wanting to install aftermarket amp/sub/speakers to my stock radio. The amp has both high and low inputs, remote subwoofer control as well as variable bass boost. For a 2008 Silverado without the factory Bose upgrade will GMs active loudness function (or higher volume variable bass reduction) require me to install a sound processor or is this what the amp’s bass boost is for?
Hi Terry, I would recommend it because that “feature” will carry over to the amp and speakers and you may find it sounds good at certain volumes and changes on you as the head unit does it’s internal processing. Can that feature be turned off on the stock head unit? Some have that option.
I read many of the comments left by other users and all the great solutions you left them with and I’m sure using a little common sense I could figure it out myself but, you have more experience than I. I have a 2006 Cadillac Sts with Premium Bose sounds system and factory sub in the back but I have just purchased the vehicle and haven’t had much time to ravage through and find out if it has a factory amp as well or where it is located. How would I be able to install the most optimal setup possible? I have a PowerAcoustik Gothic Series OV2-820 amp and Two Alpine Type E 12″ whole set up is about 10 years old but beats just as good as it did then. I have them in a 2004 Honda accord tapped in through both rear trunk speakers currently and they sound great and all but with all this new technology there has to be a way to improve, could you guide me with any way to improve my system when switching it from the Honda to the cadillac? Or do you prefer I try to purchase maybe a more up to date amp for my optimal set up. I can include pictures if needed. I did it all with a little hard work and wal mart.
Hi Mr Linville, I apologize for the late reply. You could grab your audio signal right at the stock subwoofer in the Cadillac. There should be a stock amp, but off the top of my head, I’m not sure where it is located. I hope that’s helpful!
Hi Anne i have a 2014 jeep Cherokee sport and the jeep came with no amp or subs. I replaced the stock speakers and tried to get them amped. As soon as the speakers were amped up the sound shuts off. The place where i got the amp installed said that my oem unit cant be amped. Now i have nice speakers that i cant turn up loud. Is there any amp that will work with my stock head unit
Hi Danny,
I just looked up the factory wiring diagram for a 2014 Jeep Cherokee Sport with the basic 6 speaker audio system and it’s actually very simple. The stock head unit has 4 channel audio output, there is no special can bus amplifier in this model like in the other Jeeps so there really isn’t any reason for that other than a poor installation. My guess is they either have the gains too high on the amp or they have a bad ground or maybe they aren’t using a good line output converter and the signal input to the amp maybe too much, but that can be corrected with an adjustable line output converter. Basically, you need more professional, more experienced shop to help you.
The best way to do this would be to use a processor that corrects the audio coming out of the head unit before it gets fed into the amp. We really like JL’s new processors the Fix-86 and Twk-88. I would use JL Audio’s dealer locator and try to find a more competent installer. Good luck!
Great blog
I’m looking to add a rockford fosgate p300 12″ in my 06 bmw 650i with premium sound just to add a little more bass. It already has 2 factory subs under the seats. Do I have to splice the LOC on both subs or just one? Whats the best LOC for such a job? For this vehicle where would I get the best frequency results from? Have you guys worked on such a vehicle before?
Hi Dante,
You would want to grab signal from both of the underseat subs if it’s a left and right audio signal. Usually the stock amp is fiber optic in those cars so you’ll get signal after the amp. But you’ll have to see, if it’s not fiber optic then there will be a full range signal coming from the head unit, you could use that. See attached schematics.
Question,
I really dont want to replace my factory radio (Uconnect 8 RNR system), so I am going to give a LOC a try. My main concern is controlling the volume to a subwoofer. With many aftermarket headunits, they have sub volume control so you can lower the subs volume and turn up the other speakers or vice versa. What if any options are there for this if using a factory head unit?
Hi Frank,
Towards the end of the article I mentioned the option of a separate bass control knob. Most amplifiers have their own optional plug in style bass knob accessory, but if yours doesn’t, you could use a universal bass knob like this from Pac Audio. We normally take it apart and mount the box behind a panel so all you see is the knob itself. I hope that helps!
I am hooking up after market amp in 2008 range rover and have loc converter got to factory sub but has four wires red and black also green and grey on the other side which ones do I hook up to to get bass for after market subs
Hi Dave,
I don’t know what kind of LOC you are using, it should have come with instructions that label the wire colors. I can tell you the ones we use usually have 4 wires, but they’re usually gray, gray w/black stripe, white, white w/black stripe and that represents left and right front speaker leads. If we have a factory sub we typically tie the positives together and tap into the single positive lead of the sub and negatives together and tap into the single negative lead of the sub. I hope that helps!
The red should be your + speaker lines and black – speaker lines. The two red and black closest to each other or from middle out to one side are for one speaker and the other pair for speaker #2 or it could be a single sub with dual voice coils. Either way, the system sees a second voice coil as a separate speaker anyway. The two wires on other side of the unit should be your power in and remote out to amp. When the converter detects a signal on the incoming high level side it will trigger internal relay to send 12VDC to remote wire to amp telling it to turn on. You can test those two wires by running a jumper from the + terminal of amplifier out to one of the wires (green or grey in your case). Then power on your radio head unit and Check for voltage on the other wire. So, if you connected the green wire to + of amp or any other 12VDC + you would test the gray wire with multimeter. One lead on the grey wire, other lead on ground of vehicle. If you see zero volts when radio is off and 12 volts when radio is playing then you know the green wire is your 12V in signal and grey is your 12VDC out to amp remote terminal. If you get no voltage either way, connect the grey to 12V and test the green wire.
Hi Annie,
I had my installation done by so-called professionals. I have a 2010 Camry and put 2 6×9 4-way Rockford Fosgate Punch speakers in the front doors and 2 6×9 2-way Rockford Fosgate Punch speakers in the back panel. In addition, I have a Punch Single P3 12″ Shallow Loaded Enclosure in the trunk. They are powered by: Punch 400 Watt 4-Channel Amplifier and Punch 500 Watt Mono Amplifier PBR500.
Here is the problem when I play music too load the system shuts down. The shop that did the installation put a converter and they say that everything is fine. They say the problem is with the factory radio. Could this really be the case. I don’t want to spend money buying a deck, but I guess if this really is the problem I won’t have a choice.
Hi Allan, sorry to hear about your experience, but it sounds like a bunch of unprofessional installers. Usually what will cause this is a poor ground to the amplifiers OR it’s an issue with where and how they got their audio signal for the amps. If the signal going into the amp is distorted, that could be what’s causing it shut down at higher volumes. Did you have the stock JBL amplifier in that car? Or just the basic head unit? Typically the only things that will cause an amp to shut down like that is a bad ground or a signal that is clipping causing the amp to overheat and shut down. By the way, it would sound way better with an aftermarket head unit, just an FYI. I hope that helps!
2013 Honda Accord LX 4 speaker base model.
Installed a sub and amp. (Mono amp for the sub)
When I play the radio the sound is low, lacks bass, cannot enjoy it at all. Radio volume cabln be cranked to the maximum. Dull sounding.
When I use either CD or Aux (USB) the sound get significantly louder. The bass is overpowering. The highs are sharp (intolerable).
Previously had the same amp and sub with zero distortion. There was no change in sound/volume from radio to CD. Sound was rich.
Is it possible that this car cannot be fitted with and amp and sub?
The stock set up was better than it is now.
Please Help!!
Most Honda Accords are equipped with a noise cancellation microphone in the cabin – it needs to be disconnected, that will fix your problem! It listens for “road noise” and tries to play that same frequency out of phase to cancel it out. It hears your sub and thinks it’s road noise and gets whacked out trying to correct it.
Hi Annie, I have a 2015 Chrysler 300, I installed a Kicker KisLOC off the 4 factory sub wires in the trunk. I removed the factory sub and just ran RCA’s from the LOC to my amp, which is powering a 12″ DVC Pioneer sub (wired for 4Ohms at the amp). When the install is complete and I hook back up the battery neg terminal to the car, the system works and sounds good. But when I shut my car off and then turn it back on my amp comes up with the red light protection error every time after. I have no idea why. The factory system is the beats audio. Do I need to keep the factory sub installed and wired up too?
Hi Jeff,
Not sure what’s causing the amp to go into protection mode – as a test, I would try it with your Pioneer sub disconnected and see if the amp still goes into protect mode just from cycling the ignition (with no speaker load on it). If it does, that would indicate possibly a poor ground for the amplifier. I hope that helps!
Annie
Hi Annie, I have an 06 maxima with the factory premium bose sound system. I’m not trying to do too much to it because it sounds real good. I just want to add my pioneer ts-w304r 12″ sub and dual xpe2700 400 watt amp for more bass. All i will need is a LOC with bass control, to tap into the rear stock sub and wire the amp kit like normal right? Also, the 400 watt amp has 150watts rms x 1 channel @ 4 ohms(bridged), and my sub is 4 ohms, 300 watts rms(1300 watts max). Is this amp good enough to get nice bass from the sub? Or do i need to upgrade to a bigger one before i hook it up? I want bass without having to buy a new alternator lol….
Hi Ashton, yeah you got it right. You’ve already got the equipment so I would wire it up and see how it sounds. If it’s enough bass for you, then you could use that amp. If you wanted more output, you’re already wired up so at that point you could just buy a more powerful amp and swap it out. 150 watts will add a nice little bump, but nothing too overpowering or substantial.
Hi I’m trying to connect front speakers, sub and amp in my OEM unit, but I’ll need 2 sets of rca’s to do this correct?
I’d prefer the back speakers to run off the HU, so do I splice two connections for both sets of rca’s from the front speakers? Can you do that or am I way off the mark?
Thanks
Ben
Hey Ben, it really kind of depends on your equipment. Some amps have a line output converter built in so you don’t even need to use RCA’s. If not, yeah I would grab a 4 channel line output converter and use two separate RCA cables – one run the front channel and another to the sub channel. Additionally I would get a bass knob so you can have an independent sub level volume control as opposed to adjusting the bass on the head unit which will adjust bass levels to all speakers. Some amps offer a direct plug in style specific to their amp, others don’t. You could always use a universal bass knob like this, but you’ll need an extra set of RCA cables for that feature. I hope that helps!
I just installed a aftermarket radio in my 06 Chevy Equinox, everything turns on and looks like it is working but no sound is coming out. Any ideas as to what could be wrong? I’ve triple checked the wiring and it all looks good.
You probably have a stock amplifier that needs to be powered up. Like if you have the Bose system? You would need to use the remote turn on lead from your aftermarket radio (usually blue with a white stripe) and wire that to the amp turn on lead in the car harness. I hope that helps!
Hello annie,awesome blog here! I am very familiar with audio systems and have performed all installs on my personal vehicles. I recently was stumped with my lastest install in a 2012 ram pick up truck. My question is if my oem amp is filtering out my signal to my 4 channel amp is it then best to tap the wires previous to the oem amp to achieve a better sound?.Whats happening is my door speakers are either entirely flat with no tweat,or they are all tweat. I am not getting a Full/mid tune out of my speaker..FYI its a 2012 ram 3500 with a line out converter and aftermarkyamp already in place.
Hi J,
Off the top of my head, I’m pretty sure it’s a digital signal before the stock amp so I don’t think you can get a full range pre-amp level source. That’s how most of these newer premium Chrysler/Dodge/Jeep/Ram audio systems are these days. You may need to do an audio processor that sums the frequencies off the stock amp prior to your aftermarket amplifier so you can get a true full range signal. To know what you’re dealing with exactly, I would recommend buying a vehicle wire schematic specifically for your truck from All Data DIY. We use a similar service, Mitchell OnDemand (monthly subscription required) and that allows us to see what we’re dealing with and what it’s going to take to get the wiring right. Then we test the outputs to verify whether it’s full range or cut off. These guys do WEIRD things sometimes. Like newer Jeep Cherokee’s with premium sound, they cut off the driver side door speaker at 60 Hz, but not the passenger side – crazy weird, but you just don’t know until you test it.
Hello Annie. First of all, great blog. Wow.
OK. Here are my questions. I have a 2015 F-150 with Sony premium sound system. I can see the stock amp and stock sub. I have read that the amp also powers the door speakers. If I wanted to add a mono amp to power 2 subs that I have, do I just connect the LOC into the sub connection coming OUT of the stock amp? If so, what LOC would you recommend? I have a bass knob already that connects to the kicker amp that I want to install.
I want to keep the look of my truck stock so I may swap out the stock door speakers, tweeters, and center speaker. If I do so do you think the stock amp will do the aftermarket speakers justice? I was thinking of replacing them with Polk Audio (components in the front and coaxial for the back.
Great blog. Hope to hear a response.
Thanks and have a great day.
Rob G
Hi Rob,
Thanks for the comment, I appreciate it! Ah Ford and their lovely Sony system. It’s so digital and so much fun to work with. And they have so many variations! I’ve seen some that are all digital up until the DSP amp which means you have to get your signal after the amp at the stock sub wires, but I’ve also seen some that have a left and right audio signal at the head unit before the amp. I highly recommend buying a wire schematic for your truck from All Data DIY so you know exactly what you’re working with and can see exactly which options you’ve got.
I can understand wanting to keep the look stock. If you do decide to upgrade speakers and you want to power them off the stock stereo, make sure they are efficient and while you’re in there install Dynamat as that will really help to provide a better cabinet for the speakers to operate in. I recently did this in a Subaru with Morel Tempo speakers (just did speakers and dynamat off basic stock stereo) and was pleasantly surprised at the justice the stock stereo did for those speakers. I’m not a huge fan of Polk. They’re okay, but there’s much better out there.
As far as a LOC goes, I like adjustable ones such as the Pac LP7-2. And if you ever did want to change the stereo, keep a look out for Alpine and iDatalink. I’m sure Alpine has the newer F-150’s on their radar and the iDatalink kit for the previous F-150’s is top notch OEM quality, fit, finish and interface. So in the future there may be some nice options. Otherwise you could look into a processor like JL Audio’s FiX-82 or Alpine’s PXAH800 if you ever wanted to really clean up the DSP processor and amp the speakers.
Hi Annie…Maybe you can answer two questions I can’t seem to find information on. I’ll be using a LOC to provide an RCA feed to a mono block amp. Two questions: It IS okay to run a LOC in parallel with the rear speakers…right? (Unbelievable..but nowhere have I found where its stated that its okay to do so!)… and … My HU is speked for a 2 to 4 ohm speaker impedance. Does tieing an LOC in parallel to the speaker circuit effect the circuit impedance? Thanks!
Hi Bill, I’m not quite sure what you’re asking. I think maybe you just mean running along side with rear speakers operating. Parallel has a whole other meaning in car audio and maybe that’s why you’re having a hard time finding an answer 🙂 The LOC has separate leads for left and right, positive and negative. So you want to make sure you’re getting a left and right audio signal with both left and right positive and negative leads. You’re simply tapping into those wires to get your audio feed, it won’t effect how those rear speakers are functioning in any way. For lack of a better term, the LOC is just “reading” the audio information off of those tapped leads. So you can (and are supposed to) have your LOC installed along side your rear speakers. I hope that makes sense!
Hi Annie, am trying to install 2500w 5 channel acoustik amp along withh 400 w 12″ pioneer 4ohm dvc sub to factory system in my honda accord..its a 6 speaker system 6 cd changer head unit..two of which are tweeters….my amp has an option of both high & low input as i was not sure of the availability of low level inputs from factory head unit…can u guide me on few of my queries here….firstly which inputs do u prefer sound quality wise, high level from head unit or low level by using loc? Next how do i connect the wires in any case?? Do i have to keep the harness plugged into the head unit or do i have to keep it unplugged as i read somewhere you cannot power the speakers from both factory hu and amp simultaneously..final question what is the difference if i tap the signal from harness behind hu or i tap it from each speaker individually?? And while feeding the amp output back to speakers n subs we connect speaker wires to each speaker leads, so whats the difference between amp input signal n amp output signal, its confusing me as for eg.we tap signal from rear speaker n again we feed the amp output back to same spot.. please clarify my doubts…thanks in advance..
Hi Tejas,
Definitely do more research, unfortunately I don’t have time to explain how to do your whole install, but DO NOT power the speakers off the stock head unit and the aftermarket amp. You can take the speaker leads off the back of the stock stereo and route them directly to your amp. Make sure to get your positive and negative’s correct, none of this stuff will be labeled so make sure you have the right tools to test (multimeter & battery speaker popper tester) and buy yourself a vehicle schematic for your car so you know how to identify everything (check out All Data DIY). Your stock head unit does not have RCA leads so you would be using the LOC. The LOC is your input signal. That is feeding the actual audio signal to the amp. The amplifier amplifies that audio signal and feeds it the speaker output. Hope that’s a start for you, but do some more homework before you feel comfortable tackling the project.
What if I were to tap into the factory speaker wires without the converter by cutting and splicing a rca cord?
I know my husband does this sometimes but I don’t know how he determines which vehicles it’s okay to do this in and which ones are not. I think he only does this in cars that have a stock amp and have a direct low noise pre-amp level audio signal. Hope that helps.
I have an 07 maxima with a Bose amplifier. I’m adding subs and an amp with a pac lp7-2. Problem is I don’t know which wires I should tap into. Should I tap into wires that input into the bose amp or the output wires and which colors. I currently have them connected to the 6x9s in the back but it doesn’t sound to great. I heard those are hi level outputs that’s why they sound the way they do. Someone told me to use the subwoofer outputs but there is no subwoofer in my car and if there are wires for one I don’t know which are which. Please help.
Hey Chris, sorry for the late reply, was busy trying to survive the holiday season at our shop. The rear 6×9’s are the stock subs in that car so you may either have your positive and negative mixed up (out of phase) which will greatly reduce bass or you have an issue with how you tuned your amp or something else may be going on. OnDemand lists black as negative and white as positive on the stock subs. Hope that helps.
Hello… I am installing a 500watt amp to 2 12′ mtx in my 2010 ford f-150 where is the easy spot to get to speakers for converter
Some of these trucks have a stock amp/sub – if so you can get access under the center console. Other wise, probably behind the radio.
Help please. I hooked up an amp and 12″ sub to a 2013 honda civic using an adapter to get rca jack from back speakers of said auto. Sounds great only one problem when car goes on or off i get an annoying distortion sound on subwoofer.
Hey Hugo – my guess is you’re using a line output converter with signal sensing remote turn on lead and the amp is turning on/off at a different time than the head unit causing a turn on/turn off pop. Try switching the source for your remote turn on lead to a different accessory power source.
2012 ram 2500 with alpine 9 speaker system, I believe the 430N? Removing factory sub and adding a Memphis PR 10″, using a scoche LOC90. I’ve been told to tap into the front door speakers behind the head unit, and I’ve also heard to tap into the factory sub wires at the pre existing sub. What would work best?
Hey Charles – Whenever you have an stock amplified system, most of the the time the stock amp has internal crossovers and it’s directing the lower bass frequencies to the stock subwoofer and upper and mid range to the appropriate sized speakers. So it truly depends on whether the connection behind the radio is what we call pre-amp level and actually a straight up left and right full range signal or if it’s after the amp and crossed over. When in doubt, I would go straight to the stock sub.
Hi Annie I’m hooking up a aftermarket hi-fonics Zeus 1200 watt amp and subwoofer in my friends 2003 Chrysler 300m special with the premium sound 9 speaker system and everything is hooked up correctly but I’m not getting any bass to the subs I know it has a factory amp located in the back under the deck and it also has the bass knob which is hooked up under the driver side panel under the wheel I don’t believe it has a subwoofer but I didn’t search either lol…..but what I wanted to know is how do I get power to the subs do I need a a line out converter or loc or do I need to tap into the factory amp somewhere please help I’ve been trying to figure out the nonsense all day and I’m a lil frustrated
I’m sure there’s a stock sub if it has a 9 speaker system and yes you need to signal from there and if the amp doesn’t have built in you should use a LOC.
Great stuff here. I’ve got a 2011 Tahoe with Bose. Where is the best place to hook up a line output converter when adding an amp for a sub? I may have missed it somewhere. Thanks in advance.
Hey Keith, you can grab that signal right at the stock Bose subwoofer. Off the top of my head I think it’s under the center console in that year, but not positive.
03 cadillac deville factory dvc sub. the question i have is can i run a small 10″ 10 inch mtx off the dvc on the factory sub? Like a positive one side of sub and negative on other side of factory sub ? How.many watts.does the.factory amp put out or should i just go get a loc and amp.to power it?
Maybe I’m misunderstanding your question, but it kind of sounds like you want to daisy chain the MTX off the existing amp/sub – can’t really do that. The stock amp really is not powerful enough nor designed to run the impedance of your MTX. So definitely get the LOC and a separate amp to power your MTX – you could also get an amp that has the LOC built into it too, but either way definitely just grab your signal from the stock sub, but use that signal to feed a dedicated amp to power your MTX.
I have a 2014 ram 1500 with premium alpine system. I want to add amps and a sub. The car is canbus equipped. How do I get a clean signal for amps. Anything I add must be tied in post factory amp. I need to clean the heavily processed signals. After reading a ton I still don’t have a clear solution or a recommended integration devise. MS8, SUM8, 360, but one, front row etc,, I just need clean signal. I will tune via aftermarket amps. Not interested in complicated dsp…
Hi Fred,
I feel your pain. You might want to would wait to see what JL comes up with, but it may be another 9 months or so before they release anything. They talked about this very problem at CES recently and they are in the process of designing a new product which tackles this exact issue. You can read more about the new JL Audio processor here, scroll towards the bottom of the post. In the mean time, the best processor on the market (in my opinion) is the Alpine PXA-H800. It has 6 channel audio in which can be assigned as Front (Left & Right), Rear (Left & Right) Sub (mono), Center Channel (mono).
This is our processor of choice over JL Audio Cleansweep (still good for basic stock stereo especially if can get pre-amp signal), the Audison Bit One, MS8, 360, Zapco etc. With this processor you also have the option of using a digital aux in so for a dedicated super high fidelity source, you can use an iPod running through a high quality digital to analog convertor straight into the processor. That’s how we have it set up in our Honda Element. We’re really just using the processor as the head unit, but we have had success using this processor in amplified stock audio systems (that have CAN Bus and you have to sum your signals and get them after the stock amp). I’ve never had a defective Alpine PXA-H800. With Audison I had many defective units and it would take months, even over a year in one occasion, to have them repaired or exchanged (one of the reasons we stopped carrying them).
The thing with any of these processors is you really need to set them up properly, it’s easy to screw it up. You need to measure exactly what frequency range you’re getting after the amp by doing frequency sweeps and measuring what actually comes out. Sometimes you really only need to use two audio signals. With any of these processors, if you don’t know how to set them up and install them, you can make it sound even worse than it did before. So whichever route you decide to go, make sure you go to an experienced installer who knows what a frequency sweep is, a scope is, and what an RTA is and make sure he knows how to use them because you really need all three to set up a processor correctly in a vehicle like this.
If you’re more interested in doing this yourself and want to tune via the amp, just go hi level and forget using a processor for now. Then when the Fix and the Twk comes out from JL you can clean it up even more. Those will be designed to do the tuning and tweaking themselves, making it a much simpler install. I hope that helps!
Hey I have a 2012 ram 2500 pickup with factory alpin system and touch screen deck. Has factory sub under back seat.. removed that. Had 4 wires going to that one sub.. I’m looking to install jlbsubs with Kenwood amp.. sound shop sold me a lp7 2 output converter…not sure how to wire it
Hi Chad,
Use the factory subwoofer wiring for your LOC. You still need to figure out what’s positive and negative (maybe by testing with the battery popper test with the factory sub reconnected?). It was probably a dual voice coil woofer and that’s probably why you have 4 wires, they’re probably two sets of positive and negative, but hook the factory sub back up and test to confirm OR you can always purchase a vehicle wire schematic from All Data DIY.
Hi annie i have a question if i am connecting a line out converter on a factory rafio but there are no speakers installed the wires are there and i know which ones are going to each speaker how would i find out polarity on the wires
I would look it up on my mechanic software (OnDemand – subscription based), but if that’s not an option, you can always purchase schematic access for your own car from All Data DIY. Or if you know the polarity of the front speakers, and they’re full range, you could always get the audio signal from those.
[…] to tackle this installation yourself, you may want to read my post on how to do just that – installing an amp and subwoofer with a stock audio system along with the post on how to tune a subwoofer […]
[…] How to hook up an amp and sub to a stock stereo […]
[…] How to hook up an amp and sub to a stock stereo […]
[…] How to hook up an amp and sub to a stock stereo […]
[…] to tackle this installation yourself, you may want to read my post on how to do just that – installing an amp and subwoofer with a stock audio system along with the post on how to tune a subwoofer […]
Hi there, I just bought a 2003 cadillac CTS and I wanted to know if its possible to hook up a sub and amp to the stock stereo,if I can how do I do it?
Of course you can! Did you read the post you’re commenting on? It’s all the same. Your car probably has the stock premium system so make sure you read the whole post as the last part of it describes what to do when adding an amp and sub to a stock premium sound system (I’m assuming your car probably has the Bose system in it).
I would add one clarification to your speaker polarity testing.
“If the speaker is moving out first then back in when you remove the battery, you have positive and negative correct”
At this point swap the battery wires and you will see the speaker first sucking in and then releasing back out if the polarity is reversed.
Great article. Thanks for taking the time to post it!
Thanks Johnny. For readers that need more details on polarity testing you can check out this video post or this post on wiring up a head unit when the wires have been cut.
Hi i just bought a 2010 Lincoln mkz. I hooked up a line output converter and when i shut my car off the amp begins to work and apply bass. Im not sure why this is happening i read the directions,followed step by step. Everything works fine when i turn my radio on and off the amp goes off and on….if it is the remote wire what is a proper spot to put it?? I got 2 10 inch kicker competition,and a 800 watt power bass amp,stock radio….?
Depends on what kind of line output convertor you’re using. Did you run the remote to an accessory or ignition wire in the vehicle so the amp goes on and off with the key? Sounds like maybe you used the signal sensing feature of your line output convertor, they can do funky things like that. Try to find a true accessory or ignition wire to get the timing right.
Hello, I just recently purchased a 04 Audi 2.7t s-line and it has the premium Bose system with a stock subwoofer. I have a Infinity reference 1600a mono-amp and 2x Infinity Reference 1262w 12-Inch that I used in my previous car and I have all the wiring as well (looking to upgrade in the future but its what I have for now :D). Im thinking this will be a fairly easy task since I have everything except the LOC. What im wondering is how would I wire the input to the LOC so that I can power both of my subwoofers.
Thanks ! ~
Hi Cameron,
Just tap, splice, solder, and tape the LOC off of the stock sub channel and you’ll get an RCA level connection for your mono amp. You’ll want to check the phase of the stock speaker wires. If there’s only one stock sub and one pair of wires, you can double up the wire connections so you are creating a left and right channel for the LOC (run two positive taps, two negative taps for the left and right +/- connections on the LOC). I’m not sure if you meant both of your subs as in stock subs and aftermarket subs or both subs in the two Infinity Reference subs. The Infinity subs would be wired to your amp just like any other setup. You’ll have to run your remote wire to an ignition source in the car so the amp turns on with the key and goes off with the key.
Your subs are dual 4 ohm which is not ideal when you’re running two subs and using a mono amp. Your only wiring options are running each subs voice coils series, then parallel the subs for a final 4 ohm load or wire the voice coils parallel, then parallel the subs for a final 1 ohm load. That amp is not rated as 1 ohm stable, which means you were probably running the amp at 4 ohms in your last set up. At 4 ohms it only puts out 400 watts RMS. Your subs are rated at 300 watts RMS each. I’m assuming that’s how you had it wired in your last car if it was working well, just thought you should know that those subs can handle a bit more than your amp is currently supplying 🙂
Hi!
I’m wondering how to connect my amp to my stock premium 6 deck. (03 jetta Wolfsburg edition) I have a line out converter and I know which wires are which but I’m not sure how to wire it in. Do I need to pull the rear speaker wires from the deck and wire them into the LOC? There is also no remote wire in the harness, how does my am know when to turn on?
Hi Seeber,
As far as physically how you connect them – you want to strip back the stock speaker wire, wrap your aftermarket speaker wire around that wire and solder, electrical tape, zip tie or heat shrink then connect to your LOC (obviously after identifying what’s positive and negative, what’s left and right) ). You may want to get your signal from the speaker wires before or after the stock amp which is located underneath the rear deck in the trunk. You’ll also have to find an accessory power source for the remote turn on lead which is explained in the post, you may find more assistance in how to test various wires in this post.
Hey there! I have installed an amp and speakers to my factory stereo, the problem I am having now is that every time I shut off my car and turn it back on there is no signal to the back speakers. The only way to get them to work is by unplugging the RCA’s to the amp and plug them back in, then it plays….any help would be appreciated!!
Hi Heather,
I think I know what it might be, but to really answer this I would need to know a bit more. I have a feeling that you used a line output convertor that is signal sensing or an amplifier that is signal sensing for the turn on and they’re not always reliable. If that’s the case, then just run a remote wire to an accessory power source to turn the amp on rather than relying on any signal sensing turn on feature.
If that’s not it, let me know:
-What kind of car?
-What kind of OEM system (premium like Bose? JBL? Infinity? Anything like that?)
-What kind/brand/model speakers and amp?
-What did you use to tie it into the stock system? A line output convertor? Or did you cut and splice RCA cables into the stock speaker wire?
-Where did you get your accessory for the remote turn on?
Oh and also, why does my amp shut off only 10 minutes after i start using my system?
Hi Brandyn,
Probably running too low an impedance to the amp, this is the most common issue I see. For example: If your subs are dual 4 ohm voice coil, and you wired them in parallel (positive to positive, negative to negative) that reduces the final impedance to 2 ohms. If you do that again (you have two subs, so if you connect them to one terminal on an amp you’re paralleling again) that drops it down to 1 ohm which is very unstable. Check out this post for more details.
Annie
Hello! I have a 2010 jeep wrangler and im trying to install a 1000watt pioneer amp and 2 12″ inch pioneer subs using the stock head unit that came with the jeep. Theres no stock sub or anything like that (its the low end model jeep). I’m trying to use scosche’s FAI-3A to get my signal from the stock head unit….but trying to figure that thing out is just giving me a headache lol. Its got 2 RCA out-put side (i dont know which one to use) and about 16 diffrent places to put the wires into (i thought i only needed 4 slots..so there i am confused again) I found the wires on the back of the head unit that i need to tap into (which i believe are the front speakers because they are 6×9’s and my rear speakers which are on the roll bar are 4×4’s, just dont know which set to use) If you could help me put an end to my madness Annie it would be greatly appreciated! 🙂
Hi Brandyn,
It looks like that’s a 4 channel line output convertor which is why it’s confusing you. That’s okay, you can still use it, just use one side, either the front or the rear. So if you get your signal from the front speakers, (positive & negative, left and right) use the front RCA on the convertor and likewise if you decide to use the rear speakers for signal. Since it’s the basic system, it should be the same signal either way.
Annie
Hey im having trouble with my 2006 chevy equinox can you guide me on how you would hook it up
Hi Mark,
That’s a very vague question. What are you having trouble with exactly? Running the power wire? Where to get your signal from? How to test the speakers you’re tapping for signal? How to get accessory?
Annie
I just hooked mine up in a 2009 Chevy Silverado but even with the amp on just low frequencies I’m getting vocals out of my subs which makes it sound slightly distorted. I tapped into the rear speakers before the aftermarket bose amplifier because ive heard tapping into the lines after the amp will really destroy the quality of sound. What can I do to eliminate the high frequencies coming out of the subs. I have a Razor amp and 2 Zstat Razor 12s.
Hi Daniel!
Is there a stock subwoofer??? 🙂 They’re probably is. You definitely need to get your signal from there and usually you have to get the signal after the amp as it’s usually a data signal before the amp. Look for the stock amp under the center console and look for the gray 8 pin plug, pins 7 and 3; 6 and 2. It may be different in your truck, so always use a multimeter and battery speaker popper tester to confirm wires are correct. Also, on your aftermarket amp, make sure the low pass filter is on. One more thing, I have never heard of that brand and can’t find a darned thing about them or any specs on them. Have you considered maybe the quality of the product is not up to par? Or have you used this product in other applications?
For GM trucks, I love selling custom made boxes or JL Audio Stealth Boxes. They have a few applications for GM trucks shown here and they kick ass. They’re designed for the vehicle; the car cabin acoustics are taken into consideration along with the capabilities and parameters of the subwoofer. Whenever you build an enclosure while taking into account the cabin acoustics, cabin size, subwoofer parameters, you can really build an awesome sounding enclosure. All of those things effect the sound quality and output you will achieve. If you wanted to build your own box, we like Bass Box Pro software.
I’m trying to hook up my 2006 scion TC stock subwoofer to my after market head Unit. How do I do this?
Hi Will,
Usually the Scion’s stock sub is wired in parallel to the front speakers, chances are you’re just not powering up the stock amplifier which is only for the subwoofer. The remote turn on could be a white wire in the stock radio harness (listed in directechs software for 2008 and up). You would just need to hook that up to the remote turn on lead from your aftermarket head unit (blue with white stripe).
Some cars tie the power antenna lead into the stock amp turn on wire, so if you didn’t try it, you could hook up the power antenna lead on the car side. You can do that by wiring the aftermarket head unit’s remote turn on (blue with white stripe) to the stock power antenna lead (solid blue if using aftermarket wire harness) and see if that does the trick. I would look it up on my Ondemand5 software which is more detailed and accurate than directechs, but I’m at home on my mac and it only works on PC (at work). Good luck!
Annie
also the jeep premium system did have a stock sub.
Hi Charley,
What you were doing in your last car wasn’t really control the sub. Whenever you add an amp and sub to a stock system, you have to get your signal for that amp/sub from one (or two) of the stock speakers in the car. Therefore when you adjust the bass going to your regular interior speakers, you are also adjusting the signal going to the amp. This boost in signal to the amp can result in a modest increase in bass going through your subs, but it can also put more stress on your stock speakers. Ideally, we don’t really want to send a lot of bass to them now that you have a subwoofer. With the factory premium system, the stock amp is already filtering out the bass to the stock speakers. But now when you adjust the bass, you’re not hearing a difference in your sub. Most likely this is because the signal for the sub is coming from the stock sub, not the interior speakers.
Most factory stereos (including many premium models) do not have a separate subwoofer control adjustment. So whenever I sell an amp and sub to be installed with a stock system I always sell a bass knob. A bass knob is basically a control knob that is daisy chained between the RCA connections at the amp and your high to lo level convertor. I like to use either this one from PAC or this one from JL (which also includes a line driver).
If you’ve got a good installer, he should be able to take apart the knob and install it in a very clean way that looks like it came with the car. Check out this one from a 2009 BMW 3 series we recently did.
I just had a kicker zx400 amp and 2 12″ subs installed on a 2012 jeep wrangler with the premium sound system with amp. Should I be able to control the bass through the bass adjustment on the factory radio? I had this same system installed on a 2009 gmc sierra and was able to control the bass through the factory radio bass controls but nor sure why it doesnt control it on the jeep? Any suggestions would be greatly appreciated?
Hello I have a question for you Annie? I just purchased an audiocontrol eqs to start my system upgrade in my chrysler 200 with a stock head unit. My car has 6x9s in the front and the back. im replacing them with two sets of CDT hd 6 1/2s ran off of a alpine pdx. Also i’m installing a Fi sp4 15″ in a custom built enclosure by fat box powered by a Sundown 2500D. My question is should run the line level in from the front speakers or the back speakers as they are the same size speakers. just not sure if the head unit is sending the same signal to the front and the back?
Hi Brian, good question. The only way to find out? Measure it.
To check the frequency response and make sure they are playing full range and not crossed over, you can play a frequency sweep through the front speakers, then the rear and measure the response. I like this app. If you’re missing frequencies below 80 or 60 hertz, then you know there’s probably a stock amp somewhere (which most Chrysler’s have) filtering the response.
You might be able to check the actual voltage as well with this app, but I don’t think it would be different. Personally, I’ve never used the app for that, we have a regular old oscilloscope for tests like that, but the app has that feature as well (may need additional interface, not sure).
Good luck!
maybe you can help… Is it possible to hook an OEM AM radio with the “RediRad” from a 1965 Barracuda to an amp in order to split it to run more than the one speaker it came from the factory with.
Hi Jacob,
Assuming it’s a basic set up it should be no problem: you have a stock stereo with left and right channels and a separate positive and negative for each speaker from the stereo? If so, you can:
-just use a line output convertor like this one
-replace your existing speakers and cut in/add an additional pair
-add a 4 channel amp
-use two Y adapters (2 males to one female) to Y off the 4 channels on the amp to a 2 channel connection
-use one RCA to go from your Y’d off connection to the line output convertor
You wouldn’t have a front to rear fader control. But you can tune the Front and Rear channels separately on the amp to get a balanced sound that is appealing to you. I hope that helps!
Annie
what do I got to do to hook up a high powered amp like a 5000 watt to my stock head unit, it has navigation on it. Have a 08 ford shelby gt500.think it has the shaker 500 unit.
Sorry, saw this comment after I responded to the other one. So definitely the upgrades for wiring I mentioned earlier. You will need a line output converter as mentioned in this article and definitely an adjustable one like the Stinger one that is shown. And since you have the Shelby model, you’ve already got the factory amplifier and a factory sub so you will need to play around with where you get your signal from. Sometimes you need to go before the amp, sometimes after. Every car is different, but I would try it at the factory sub first, see how it sounds and then go from there.
does it make any difference if u wire the line out converter to one of the rear speaker wires or is the LOC best been wired up directly from the sterio?
Hi Cammy, you really should get signal from both rear speakers as your factory stereo is putting out a stereo signal to the rear speakers and the amp wants to see stereo mixed into mono. You can grab those wires either at the speakers themselves or behind the radio. Just make sure to test for positive and negative so nothing is out of phase.
Hi I have n 07 Cadillac CTS none Bose but have an amp n stock head unit I put coil axe pioneers in the doors I have a stock sub in the rear deck I pick up a bazooka tube self amp I tried to wire behind amp did not work tried head unit did not work says it’s easy install not in this case any advice I have a loc but some say behind radio n I heard u say at the sub if u have any advice pls I’d appreciate it
Unless you can get a full range signal behind the head unit you should get your signal at the stock sub. You still need to run a remote turn on lead to the amp from an ignition power source (unless you bought a signal sensing LOC with remote turn on lead).
hi,
i have a 2000 saab 9-3 SE with the premium sound system, factory amp and two mini subwoofers (kinda blown) but changed one already to an infinity kappa 62.9i and sounds horrible for some reason. But my question is, i just bought an infinity reference 1600a amp and want to hook it up but not sure what kind of subwoofer i will go good with it ? and also a list of all of the wires i need or adapters before i get started.
any help will be appreciated
thank you
Hi Jesse,
That’s a nice amp, it’s 600 watts RMS at 2 ohms and it’s a mono amp. I’m curious, when you stay stock subwoofers, where were they located? I’m not a huge fan of those Infinity speakers, but in their defense, you are running them through the stock Saab stereo and stock amp, which was specifically designed and tuned for the original Saab speakers. So until you change the stereo, you won’t really get the full potential of the speakers.
The other possibility here is your phase is incorrect, are you sure you got positive and negative correct? Stock wiring is never color coated to be anything like aftermarket wiring. For example, positive in most Jeep Grand Chrerokee tweeters is usually black, and negative is green. If you have one or both of the speakers out of phase compared to all the other speakers in the car, it will sound pretty bad. One way to check this is try fading just to those speakers, than balance it left and right. If they sound better playing alone, you’ve got your phase screwed up somewhere between those speakers (one is out of phase). If they sound good together, but sound crappy when mixed with the rest of the car speakers, you’ve got them both out of phase with the rest of the system.
If you’re going for sound quality, I would recommend one good 12″ rated around 600 watts with a 2 ohm load in a sealed box (either single voice coil, or dual 4 ohm wired in parallel down to 2 ohms). A JL W3 or W6 would be nice, an Alpine Type R, the Hertz Energy series or Hi-Energy series subs are great sounding too.
If you’re going more for output and sound quality, go for two 12″‘s rated around 300 watts each and they would need to be either single voice coil 4 ohms or dual 2 ohms, also sealed box. The larger surface area will give you a little more kick.
As for wiring, you’ll need a 4 ga wiring kit, you’ll probably want to get a subwoofer control knob. JL makes a nice one, the CL-RLC. If you do that, you’ll also need 1 additional set of RCA’s, assuming the amp kit you buy comes with one (there is an in and an out on the control knob). You’ll also need a hi to lo level convertor (Stinger has a nice one SGN13. And you’ll need some speaker wire, check the amp kit, many come with it, but not all of them.
Very important tip here, if you are adding the amp and sub to the stock deck, you must get your signal using that hi to lo level converter at the stock subs. If you don’t, if you go to a midrange or tweeter, you’ll be feeding your amp midrange or tweeter frequencies and you won’t get any bass.
Good luck!
-Annie
Terrific work! This is the type of information that should be shared around the web. Shame on the search engines for not positioning this post higher!
Thank you for the kind words, I really appreciate the input.
Hello Annie, I have a 2012 Chrysler 300C and I want to hook up a amp and a sub. I read some of your blogs but want to get more specific with my car. It has a Harmon Carmen premium system. Is it possible to just hook up a LOC to the rear factory sub and then just run the amp from there?I was also wanted to know if it would be beneficial to put in a digital bass reconstruction box in line with this? along with the remote nob to control the bass. Thank you for your time and consideration to replying to this question. David.
Hi David,
Yeah, definitely tap your audio signal off any stock subs in the vehicle. I do like the Audio Control Acubass LOC for digital bass restoration. It’s helpful in any stock audio system that is self attenuating. Meaning if the bass level if your stock stereo stays steady output, despite raising the volume from low to high, if it stays pretty even through out it’s probably self attenuating. Having a bass knob is nice even if you have an aftermarket stereo. Bass levels vary so widely from recording to recording, it’s really helpful to have. Keep in mind you’re only getting your audio signal from those stock subs, you will still need to run traditional power wire from the battery, ground the amp, etc like any other install. Hope that make sense and I understood your question correctly!