[How-To] Subwoofer Upgrade - Replacing/Upgrading the Factory Sub

[RagnarKon]

@RagnarKon with the 23MY w/ sub delete, could I make the kicker 8 fit with some limited cutting like you did? or is it smaller in other ways as well and not suited.

You can make it fit.

@Rydfree actually just made a post over on Bronco Nation with his upgrade that does exactly that—fits an 8” sub into the sub delete enclosure.

——

Also… for you 2-door people, he did a good job of snapping a photo or two with the clip locations—his post is worth a look if you have a 2-door.

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[Muddog899]

I saw the pics but didn't save them now I can't find them.

 

[STONEWALKER]

If you watched my last video you will know that I installed the B&O subwoofer. This time I have upgraded that B&O subwoofer with a Kicker 8" sub!

Check below the video for a TON more information that I've collected.

Other videos/guides I've created on the topic of audio upgrades:

• [How-To] Factory Bronco Speaker Replacement
• [How-To] Amp Install - Kicker Key 200.4
• [How-To] FORScan Audio/Speaker Mods
• [How-To] Subwoofer Upgrade - Trim panel removal & Kicker install

AUDIO SYSTEM VARIANTS

As of now (mid-2023) there are four variants of audio systems in the Bronco. How you add/upgrade your subwoofer will depend on which setup you have.

2021 - 2022MY Six-Speaker
This was the audio system that was included in all non-Lux packaged Broncos. There is NO factory subwoofer, nor is any wiring available to support a subwoofer.

2023MY Seven-Speaker
Included in early 2023MY Broncos. This is identical to the 2021 - 2022MY setup, with the addition of an amplifier and a subwoofer.

2023MY Seven-Speaker with Sub Delete
Ford messed up and ran out of subwoofer components. Functionally the same as the 2021 - 2022MY setup. HOWEVER, it contains the wiring and enclosure necessary to hook up a subwoofer & amplifier.

2021 - 2023 B&O
This is the premium audio system included with the Lux package. There are 7 speakers with a single subwoofer measuring roughly 8" in size (a little less than 8" to be exact).

PICKING YOUR SUBWOOFER

At a high level... there are three decisions you need to make when picking a subwoofer:

• Voice Coil Impedance
• Speaker diameter & depth
• RMS power requirements

In addition those three items, there are other specifications such as frequency response, sensitivity, etc. etc. Most people will not have to worry about these items unless they are really trying to optimize their setups. Given I am gearing this post more towards the novice DIY type... I am going to ignore these items. However, you are free to ask questions about these topics or look online. In addition, if any of you car audio pros feel like there is an important aspect I am ignoring... post in in the comments.

Voice Coil Impedance

You will find that subwoofers intended for car audio generally come in two impedance ratings: 2Ω and 4Ω. There is a lot of electrical and power engineering I could dig into, but just to generalize it:

2Ω voice coils will be much louder and more more "boomy", as they can handle more power flowing through the voice coils. Those who dislike 2Ω voice coils often describe it as sounding very "sloppy", while those that like it often describe the bass as very "full" sounding. If you are driving those 2Ω voice coils with an underpowered amplifier, you run the risk of overheating your amplifier and/or creating very "muddy" sounding bass.

4Ω voice coils will have a more tight and clean sound. Uses less power than 2Ω voice coils, and generally more "safer" for underpowered amplifiers. For this reason... if you are running a factory amplifier rather than aftermarket, I generally recommend sticking with 4Ω voice coils. Those who like the sound of a 4Ω subwoofer would describe it as "accurate" sounding, while someone who dislikes 4Ω voice coils will often say it sounds "constrained".

Speaker Diameter

Generally speaking, the bigger the subwoofer the better. BUT, the bigger the subwoofer the more power and space it will require. Unless you are willing to devote your entire cargo space to a subwoofer, most of us will have to come up with some sort of compromise when it comes to the size of the subwoofer.

If you are mounting your subwoofer in the factory location—in the cargo area passenger side panel—you have two sizes available: 6.75" and 8" subwoofer speakers. BUT, there is aftermarket enclosures available—more on this in the enclosure section.

Obviously your subwoofer will need to be able to physically mount inside of whatever enclosure you select. This will be highly dependent on which enclosure and subwoofer you select, and there is a near-infinite amount of combinations available. The only real advice I can give here is "RTFM and measure before buying".

RMS Power Requirements

Obviously you need to pick an amplifier that is capable of powering your subwoofer. More on that in the next section...

PICKING YOUR AMPLIFIER

There is a TON of amplifiers out there in the marketplace. I definitely encourage you to shop around, and gather suggestions from the forum.

One of the more popular amplifiers is the Kicker Key 500.1, which is the amplifier I personally selected—largely because it was compatible with the Plug-n-Play Kit I bought. My brother—who generally knows more than me about car audio—also suggested the Kicker CX series of amplifiers. In my past I would have highly suggested AudioControl amplifiers, but admittedly I have zero experience with their current product offerings.

Arguably the most important part of any subwoofer amplifier is the amount of power it can deliver at a given impedance rating. It's probably easiest to explain this using an example...

Pretend I have selected the following components:

• Amp: Kicker Key 500.1
• Sub: Kicker Comp RT 48CWRT84

The amplifier I have selected has the following specifications. Notice that the maximum power output of the amplifier depends on the impedance rating of the subwoofer.

The subwoofer has the following specifications. Notice the recommended amplifier power is 300 watts. This is the recommended power output when the subwoofer's voice coils is wired in parallel.

What does this parallel business mean?? Well... there is two ways to wire a dual voice coil subwoofer. If you wire subwoofer in parallel, the impedance rating seen by the amplifier is HALF of the value of the voice coil rating. If you wire the amplifier in series, the impedance is DOUBLE the value of the voice coil rating. A 2Ω subwoofer in parallel will cause the amplifier to see 1Ω of impedance. If that same subwoofer is wired in series, the amplifier will see 4Ω of impedance. Wiring diagrams below:

In this case, our subwoofer has 4Ω voice coils, and when wired in parallel, the impedance seen by the amplifier is 2Ω. The Kicker Key 500.1 is rated for 300 watts and 2Ω impedance, which matches the subwoofer's requirements. So we're good to go.

Modern amplifiers are also typically packed with a ton of added features that you may or may not find helpful. Definitely read user manuals, check out reviews online, etc. etc.

SUBWOOFER ENCLOSURE

General speaking there are three choices for subwoofer enclosures:

• Using a powered subwoofer. This has the amplifier, the subwoofer speaker, and the enclosure in a single unit. The Kicker Hideaway series is a popular example of a powered subwoofer.
• Using an external enclosure. This can be as simple as an standard subwoofer box you stick in your cargo area, an enclosure that mounts to your tailgate—such as the Stinger TXFBB12, or even a DIY box you built yourself.
• Mounting it to the factory location. Three options for this:
  • 2023MY base audio enclosure - 6.75" enclosure
  • B&O enclosure - 8" enclosure
  • Aftermarket enclosure, such as the JL Audio Stealthbox.

Personally, I like the factory location as I value my cargo space, but obviously the choice is yours.

Whichever you decide... check your measurements.

HOW TO WIRE YOUR SUBWOOFER AMPLIFIER

Obviously this will vary widely depending on exactly what gear you purchase. So I am going to speak in extreme generalities. If you need help filling in the gaps, let me know.

POWER

Most people will have to pull their amplifier power from the battery, but the 2023 have the option to pull their power from the factory wiring, assuming they have a relatively low-powered amplifier.

Variant	Power from Battery	Power from Factory Wiring
'21-'22 Six Speaker	Yes	No
'23 Seven Speaker	Yes	Yes, but careful (12 ga. wire)
'23 Seven Speaker (Sub Delete)	Yes	Yes, but careful (12 ga. wire)
'21-'23 B&O	Yes	No

GROUND

Just about everyone will be able to use the ground near the passenger rear cargo area behind the panel. Those with the 2023MY may also use the factory wiring provided, but keep in mind the ground wire should be the same gauge as the power wire or larger (thicker cable).

AUDIO SIGNAL

This is where it gets interesting...

'21-'22 Six Speaker

Those of you in the unlucky 2021-2022 6-speak camp will have to steal their subwoofer amplifier signal from the left and right kick panel speakers. There really is no other way around it. Of course, certain amplifiers and kits made by companies such as @plugnplaykits can make this task substantially easier for you, but fundamentally it all has to come from the kick panels.

Factory Setup

With Subwoofer Upgrade (Proposed)

'23 Seven Speaker / '23 Seven Sub Delete

2023MY Broncos have all of the wiring in place for an amplifier, regardless of whether you have the sub delete option or not. Upgrades are as easy as taking the old amplifier/subwoofer out (or their fake equivalents), and installing the new amplifier and subwoofer.

Note the 2023MY Broncos with the sub delete option will need to use Forscan to turn on the subwoofer output from the ACM. This output will be a low level (aka: line level) output, not a high level (speaker level) output.

Factory Setup

Factory Setup - Sub Delete

With Subwoofer Upgrade (Proposed)

'21-'23 B&O Package

The B&O package makes it tricky. The amplifier in the rear of your Bronco near the subwoofer is not just a simple amplifier. It is an entire digital signal processor (DSP) that also powers more than half of the speakers in your Bronco. That DSP talks to the factory Audio Control Module (ACM) over a digital connection using a protocol called A2B. Therefore you cannot simply replace the DSP with an amplifier.

There are several companies out there that have aftermarket equipment capable talking on the A2B protocol. BUT, if you are simply going for a factory subwoofer upgrade, your amplifier will have to daisy-chain off of the B&O DSP output.

Factory Setup

With Subwoofer Upgrade (Proposed)

MY PERSONAL SETUP

I have a 2022 Bronco with the standard 6-speaker setup. To feed the subwoofer amplifier I am using a Plug-N-Play kit from @plugnplaykits. That kit steals the signal from the front kick panels, passes it through a load resistor to clean up the signal a bit and give the factory ACM something to look at, and passes it back over the wiring hardness to a Kicker Key 500.1.

OTHER THREADS/VIDEOS...

These are thread I've come across that I felt were extremely helpful. If you got one I missed, link it and I'll add it to this list.

Threads

• 2023MY Speaker Upgrade Megathread
• @jshapz - 2023 7 speaker subwoofer upgrade
• @cmcbronco - B&O sub installed on Base Bronco ….sorta….
• @John P. - John’s 2 Door Badlands Build (B&O Replaced with Active DSP)
• @Ksjrb03 - B&O sound system complete upgrade - Done

Videos

• Kicker Hideaway Powered Sub Install
• @1Five1 Garage - Interior Trim Removal and Soundproofing

FACTORY WIRING DIAGRAMS

Hope that was helpful!!!

You never disappoint my brother! I tell everyone I can about your YouTube channel. Keep up the awesome work

 

[Muddog899]

So following this thread and others, made speaker upgrades to my 2 door and did the sub woofer with a kicker 8 in to factory sub box plus made all the forscan changes. To send full power to the rear speakers and the sub, but never really liked the sound of the system. Sounded hollow and muffled so made more changes today in forscan. I set my checksums back to the default settings but left the sub output on. Too my ears it seems to sound better now.

 

[Nolequad]

Question for anyone who has tapped into the wiring harness on the 7 speaker MY23...

Not in front of it all now, but was earlier today and have closed it all back up. I'm thinking I did the wiring wrong. So on the brown harness that goes into the fake amp (or real) there is the purple/green wires which I know are +\- for the speaker. There is also a larger guage black wire I presume is the ground. Then there are 2 more wires, one is larger guage yellow/red and the other is smaller yellow/purple. Looking at a picture I took earlier I think I wired this wrong. Does the larger yellow/red wire have constant voltage (12v?) And the smaller yellow/purple switch on with the radio? I wired a relay to the larger yellow/red wire and don't think my amp is turning off. I shut off the fuse (power to amp) by the battery for now until I have time to open it back up but trying to do some mental planning.

 

[RagnarKon]

Question for anyone who has tapped into the wiring harness on the 7 speaker MY23...

Not in front of it all now, but was earlier today and have closed it all back up. I'm thinking I did the wiring wrong. So on the brown harness that goes into the fake amp (or real) there is the purple/green wires which I know are +\- for the speaker. There is also a larger guage black wire I presume is the ground. Then there are 2 more wires, one is larger guage yellow/red and the other is smaller yellow/purple. Looking at a picture I took earlier I think I wired this wrong. Does the larger yellow/red wire have constant voltage (12v?) And the smaller yellow/purple switch on with the radio? I wired a relay to the larger yellow/red wire and don't think my amp is turning off. I shut off the fuse (power to amp) by the battery for now until I have time to open it back up but trying to do some mental planning.

Yellow-Red is the 12 volt power for the factory amplifier. That should be a 12-gauge wire.

Yellow-Purple is smaller gauge and is the signal used to tell the amplifier to turn on.

 

[Nolequad]

Yellow-Red is the 12 volt power for the factory amplifier. That should be a 12-gauge wire.

Yellow-Purple is smaller gauge and is the signal used to tell the amplifier to turn on.

Explains my mistake

 

[zone23]

I'm sure this has been asked but I'm gonna ask it anyway. Can someone recommend a panel removal tool kit with fasteners please. I see some on amazon just not sure what everyone else is using. I'm thinking I'm going to replace my sub but want to have the tool kit and the fasteners on hand before I tear into it. I want to remove it once and put it back together and have be right and done. Thanks for your help.

 

[RagnarKon]

I'm sure this has been asked but I'm gonna ask it anyway. Can someone recommend a panel removal tool kit with fasteners please. I see some on amazon just not sure what everyone else is using. I'm thinking I'm going to replace my sub but want to have the tool kit and the fasteners on hand before I tear into it. I want to remove it once and put it back together and have be right and done. Thanks for your help.

I have a Craftsman CMMT98334 that I got on sale several years ago for less than $10. That kit is extremely overkill for what you need, and I will freely admit there are 2-3 tools in that kit I've never used before.

You only need a simple 4 or 5 piece set of trim removal tools similar to this. The quality of the kit doesn't really matter to be honest, because these are cheap plastic tools that are intended to be cheap plastic so they don't scratch the interior trim. The metal claw that is included in many kits is also unnecessary for interior trim, that's generally speaking intended for exterior trim and plastic panels in the engine bay.

As for the clips/fasteners themselves... if you break any of the clips it will likely be the white 2-piece retainer pins. Those are not common clips so you are unlikely to find them online in a trim panel removal kit. But they can be bought from your dealer's parts counter (or online): Part No. W721378-S300. (I managed to remove the panel without breaking any of the clips though, so up to you if you want to buy those ahead of time.)

 

[Karl_in_Chicago]

I'm sure this has been asked but I'm gonna ask it anyway. Can someone recommend a panel removal tool kit with fasteners please. I see some on amazon just not sure what everyone else is using. I'm thinking I'm going to replace my sub but want to have the tool kit and the fasteners on hand before I tear into it. I want to remove it once and put it back together and have be right and done. Thanks for your help.

I bought this $5 kit years ago from Amazon. I'm sure people that do this kind of work for a living have better and more substantial kits (and can probably do it with just fingers or any old prying thingie) but it's done fine by me. As RagnarKon notes the clips that might break aren't typically going to be found in one of those assortments you can pick up. Watch the videos and maybe print out (or copy to a local device) the picture(s) referenced here that show the clip locations for day-of reference and there's a real good chance you can remove the panels without issue. Worst case you break one or two and then order them if/when you need them. A loose trim panel won't keep you from driving.
Good luck!

 

[Muddog899]

Took it apart again added poly fill and some sound deadening to the housing area and on the sub box itself. I also plugged up the port seems like it hits a bit harder sharper.

 

[Nolequad]

Update from my install with a few learnings that may be helpful for others:

First, I had the MY23 sub-delete and installed a Kicker Key 500.1 with an 8" Kicker 48CWRT84 woofer. Very similar to what many others have done.

Some wiring and other tips I hadn't seen well documented elsewhere (and apologies for limited pictures):

• I ripped the female connector out of the fake amp box to use as a connector for my wiring... this worked great and meant I didn't have to T-tap or splice a single factory wire. To make this work I pulled out all the pins that are not being used and then put some glue on the back of the connector the keep the pins in place. (you can see the brown harness in the pic below)
• I used a PAC TR-4 to wire my remote wire for the amp (wired it wrong the first time but easily fixed) and it worked great. I just connected the low voltage detection wire to the small yellow/purple wire in the factory sub wiring harness (obviously activated everything with Forscan)
• I connected an old RCA cable to the factory sub wiring harness (via the connector in the first bullet)... to do this I just soldered the 2 positives from the RCAs (center pin) to the purple (+) wire and then the shield wires to the green (-) wire on the harness. Was able to then just connect that RCA cable to the amp wiring harness.
• I turned my lo-pass all the way up to block as many of the low frequencies as I could because of port noise (more on that below).

You can see some of it in this picture I took before I cleaned all the wiring up:

My takeaways from this setup:

• Overall this sounds much more full than the stock setup and am fairly happy with where things are. Granted there is still a ton of room for improvement. The bass is pretty clean at low volumes and has good punch.
• The port noise on the factory enclosure is very very real... it sounds like the box is farting when the bass gets too loud and especially on lower frequency tones. Would love any feedback anyone here has on how to reduce this... does polyfill really help? I've seen a lot of people talk about sealing the box which I now understand. I may eventually just have to replace the enclosure.
• Having a bass knob was the real deciding factor to go with the 8" and kicker amp vs an easier install.
• Took almost 5 hours to fully install... allow yourself time if you do this.

Lots more thoughts I could share but will save for now.

 

[RagnarKon]

The port noise on the factory enclosure is very very real... it sounds like the box is farting when the bass gets too loud and especially on lower frequency tones. Would love any feedback anyone here has on how to reduce this... does polyfill really help? I've seen a lot of people talk about sealing the box which I now understand. I may eventually just have to replace the enclosure.

This is a side-effect of using a ported enclosure that is too small and poorly setup for the subwoofer. In the custom audio industry this is known as "chuffing". Polyfill will help a little bit, but it won't really fix it completely.

The only real fix is to seal the enclosure, but there is a trade-off.

• Downsides:
  • You will have to push more power through the amp and subwoofer to get the same audio level
  • You lose a lot of the natural extension into the lower frequencies since the subwoofer enclosure isn't there to help out. There will be a rather dramatic roll-off lower than ~35 Hz or so.
  • You have to ensure it is air-tight, otherwise it wont be optimal. It's kind of a pain to make the factory enclosure air tight.
• Upsides:
  • A tighter and cleaner bass sound (typically good for music with a lot of synthetic noises)
  • No more chuffing

I ran into the same issue, but opted to leave it ported. I've always preferred ported enclosures with the type of music I listen to (rock) because it creates a larger sound stage. And once I tuned the enclosure and setup my filters properly I was able to minimize the chuffing. Don't get me wrong, the chuffing is still there--the enclosure is still too small for that subwoofer and obviously I can't defeat physics. But I didn't want to sacrifice the low end extension by sealing up the enclosure.

It there was a 10" subwoofer in there I would have sealed it for sure. But 8" is kind of on the line... its just too small of a subwoofer to really give you a good bass response below 35 Hz in a sealed enclosure, but too big for the ported enclosure we are trying to stick it in

Got a video on it from a few weeks ago (second half of the video). This was before I decided what to do, but shows you the steps I took to figure it all out:

 

[Nolequad]

This is a side-effect of using a ported enclosure that is too small and poorly setup for the subwoofer. In the custom audio industry this is known as "chuffing". Polyfill will help a little bit, but it won't really fix it completely.

The only real fix is to seal the enclosure, but there is a trade-off.

• Downsides:
  • You will have to push more power through the amp and subwoofer to get the same audio level
  • You lose a lot of the natural extension into the lower frequencies since the subwoofer enclosure isn't there to help out. There will be a rather dramatic roll-off lower than ~35 Hz or so.
  • You have to ensure it is air-tight, otherwise it wont be optimal. It's kind of a pain to make the factory enclosure air tight.
• Upsides:
  • A tighter and cleaner bass sound (typically good for music with a lot of synthetic noises)
  • No more chuffing

I ran into the same issue, but opted to leave it ported. I've always preferred ported enclosures with the type of music I listen to (rock) because it creates a larger sound stage. And once I tuned the enclosure and setup my filters properly I was able to minimize the chuffing. Don't get me wrong, the chuffing is still there--the enclosure is still too small for that subwoofer and obviously I can't defeat physics. But I didn't want to sacrifice the low end extension by sealing up the enclosure.

It there was a 10" subwoofer in there I would have sealed it for sure. But 8" is kind of on the line... its just too small of a subwoofer to really give you a good bass response below 35 Hz in a sealed enclosure, but too big for the ported enclosure we are trying to stick it in

Got a video on it from a few weeks ago (second half of the video). This was before I decided what to do, but shows you the steps I took to figure it all out:

RagnarKon, your insights and videos have been a huge asset for me on this project. In fact the reason I knew to crank the lo-pass up on the amp was your video. Really appreciate the time you've put into all this.

I'll probably leave it ported for now as well--as you noted it's less problematic for rock music and becomes more annoying on rap songs with deep lingering bass. I thought about sealing it up but worried if it didn't work well I'd have a real mess on my hands.

 

[mtnbiker]

Update from my install with a few learnings that may be helpful for others:

First, I had the MY23 sub-delete and installed a Kicker Key 500.1 with an 8" Kicker 48CWRT84 woofer. Very similar to what many others have done.

Some wiring and other tips I hadn't seen well documented elsewhere (and apologies for limited pictures):

• I ripped the female connector out of the fake amp box to use as a connector for my wiring... this worked great and meant I didn't have to T-tap or splice a single factory wire. To make this work I pulled out all the pins that are not being used and then put some glue on the back of the connector the keep the pins in place. (you can see the brown harness in the pic below)
• I used a PAC TR-4 to wire my remote wire for the amp (wired it wrong the first time but easily fixed) and it worked great. I just connected the low voltage detection wire to the small yellow/purple wire in the factory sub wiring harness (obviously activated everything with Forscan)
• I connected an old RCA cable to the factory sub wiring harness (via the connector in the first bullet)... to do this I just soldered the 2 positives from the RCAs (center pin) to the purple (+) wire and then the shield wires to the green (-) wire on the harness. Was able to then just connect that RCA cable to the amp wiring harness.
• I turned my lo-pass all the way up to block as many of the low frequencies as I could because of port noise (more on that below).

You can see some of it in this picture I took before I cleaned all the wiring up:

My takeaways from this setup:

• Overall this sounds much more full than the stock setup and am fairly happy with where things are. Granted there is still a ton of room for improvement. The bass is pretty clean at low volumes and has good punch.
• The port noise on the factory enclosure is very very real... it sounds like the box is farting when the bass gets too loud and especially on lower frequency tones. Would love any feedback anyone here has on how to reduce this... does polyfill really help? I've seen a lot of people talk about sealing the box which I now understand. I may eventually just have to replace the enclosure.
• Having a bass knob was the real deciding factor to go with the 8" and kicker amp vs an easier install.
• Took almost 5 hours to fully install... allow yourself time if you do this.

Lots more thoughts I could share but will save for now.

Thanks much for sharing this. I'm taking a similar approach (everything opened up at the moment). The Large Yellow/Red line is power from ACM, right (12 gauge?)? Did you also solder a power cord to the appropriate pin, or did you route power separately from the battery? I'm using the kicker 500.1 amp, as you did. Looks like 8 gauge wire is recommended, so likely separate power from battery?

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