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

[RagnarKon]

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 110 watt amplifier and a 170mm (~6.75-inch) 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 the 170mm 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 200mm (roughly 8") in size.

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 - 170mm enclosure (~6.75")
  • B&O enclosure - 200mm enclosure (~8")
  • 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-speaker 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 harness 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/Sub 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!!!

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[Bronc-Itus]

 

[da_jokker]

Do you know where the remote wire is? ... A real one that comes on with the radio, irregardless of what the ignition button is doing? The add a fuses don't work because either they are always hot, or turn off with the ignition.

Based on some feedback from some Plug n play kit people, sounds like it is possible.

 

[RagnarKon]

Do you know where the remote wire is? ... A real one that comes on with the radio, irregardless of what the ignition button is doing? The add a fuses don't work because either they are always hot, or turn off with the ignition.

Based on some feedback from some Plug n play kit people, sounds like it is possible.

It's pin 23 on the second wiring harness with the gray connector on the Audio Control Module. The 2021/2022MY Broncos with the base sound system don't even utilize that pin. For the B&O Broncos and 2023MY it's a yellow/purple cable if I recall correctly.

The Plug-n-Play kits only plug into the first wiring harness... it doesn't give you access to that pin, so you'd have to manually splice into it.

 

[talbot]

Great info, thans Bryan
bookmarked for future upgrade

 

[MKZoom]

a few things to note:
#1 impedance of the coil has little effect on how a speaker "sounds", it is the result of design decisions made during development of the speaker. the impedance of the speaker should be selected with thought of the amplifier that will power it.
#2 the B&o speaker is a neodymium speaker which has a much more powerful and thus smaller magnet. this is why is it lighter and smaller on the back side.
#3 you would be correct that in the vented enclosure you only want an air path through the vent. any time you are using a vented enclosure you need to be mindful of the speaker that is being used in it, a subsonic filter is typically recommended.

overall great work on showing all the steps and each hurdle you ran into.

 

[RagnarKon]

a few things to note:
#1 impedance of the coil has little effect on how a speaker "sounds", it is the result of design decisions made during development of the speaker. the impedance of the speaker should be selected with thought of the amplifier that will power it.
#2 the B&o speaker is a neodymium speaker which has a much more powerful and thus smaller magnet. this is why is it lighter and smaller on the back side.
#3 you would be correct that in the vented enclosure you only want an air path through the vent. any time you are using a vented enclosure you need to be mindful of the speaker that is being used in it, a subsonic filter is typically recommended.

overall great work on showing all the steps and each hurdle you ran into.

#3 actually reminds me of something I should ask to see if anyone knows the answer.

Does anyone know what the B&O enclosure is tuned for??

The Kicker Key 500.1 has a subsonic filter built into the amplifier, but without knowing what frequencies the B&O enclosure is tuned for there is a lot of guessing on my end, and I'm looking for a shortcut.

 

[Plowman1973]

Will a 12” kicker solobaric L7 fit in factory spot? Do you think it will be too heavy to work on the tailgate door?

 

[RagnarKon]

Will a 12” kicker solobaric L7 fit in factory spot? Do you think it will be too heavy to work on the tailgate door?

You MAY be able to fit a 12" subwoofer in the cavity, but you'll have to come up with a custom mounting solution, and you'll probably have to mount the amplifier elsewhere. You're looking at a 700-800 watt amplifier to power that subwoofer, and you definitely will not be able to fit the subwoofer and the amplifier of that size in that cavity with adequate cooling. There is little to no airflow in that cavity, so unless you mount some fans to get some air passing through that side panel it's going to get toasty.

If you maximize the space available you should be able to fit a 10" and an amplifier.

 

[Plowman1973]

You MAY be able to fit a 12" subwoofer in the cavity, but you'll have to come up with a custom mounting solution, and you'll probably have to mount the amplifier elsewhere. You're looking at a 700-800 watt amplifier to power that subwoofer, and you definitely will not be able to fit the subwoofer and the amplifier of that size in that cavity with adequate cooling. There is little to no airflow in that cavity, so unless you mount some fans to get some air passing through that side panel it's going to get toasty.

If you maximize the space available you should be able to fit a 10" and an amplifier.

Thanks for the info. I have 2 of those subs from another truck and I wanna reuse 1 if not both in some capacity

 

[MKZoom]

#3 actually reminds me of something I should ask to see if anyone knows the answer.

Does anyone know what the B&O enclosure is tuned for??

The Kicker Key 500.1 has a subsonic filter built into the amplifier, but without knowing what frequencies the B&O enclosure is tuned for there is a lot of guessing on my end, and I'm looking for a shortcut.

~26Hz iirc, placing a speaker with a much larger magnet volume inside it will push that a TINY bit higher though.

 

[MKZoom]

in regards to the 12", i think it would be way too big to fit.

it a common misconception that you NEED multiple hundreds of watts to power larger speakers.
remember that the power to output ratio works logarithmically. doubling your power from 300 to 600W only gives you an additional 3db. 3db is significant, but the increased cone area from a larger speaker can often make up for the reduced sensitivity at low frequencies.

 

[eduard4us]

Another great thread Brian!! Great work as always, bookmarked for future.

 

[mhtucker78]

Great vid as always! I like how as you progress you have more bandaids on.

 

[RagnarKon]

Great vid as always! I like how as you progress you have more bandaids on.

Oh gosh... someone noticed.

At one point in the day I had 7 bandaids on my hands. Four from the utility knife, one from the Dremel, one from a particularly sharp plastic clip, and a mystery cut from who knows what.

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