2025 R1T Tri Max - Subwoofer Replacement - Upgrade to Premium Audio

[ForeverWild]

This is my take on the subwoofer replacement in what was supposed to be "Premium" audio in the 25 R1T Tri Max.

Quite frankly, Rivian was very close to having premium audio, but dropped the ball on this by installing a 6x9 speaker in place of a good-quality sub. Maybe, by the time of this writing, this has changed.

The combination of the latest software, 2025.14.30, and the replacement sub makes this a truly premium audio system. It sounds amazing! No adjustments to the EQ! My wife, who never agrees with me on anything, let me tell you, even the color of the sky, was actually impressed by how good it sounds now.

The goal here was simple:
1. Make it easily reversible in case you want to sell the vehicle, service, or upgrade, etc.
2. Make it sound good, but not nuts (I don't know how either-wise to describe it).
3. Reduce any vibration coming from the sub onto the vehicle chassis (probably on overkill).
4. Maintain the under-the-seat storage space.

What did I use (BOM):
JL Audio 8W3v3-4 (8" 4-ohm subwoofer) - $349
JL Audio JD250/1 (JD Series mono subwoofer amplifier — 250 watts RMS x 1 at 2 ohms) - $229
JL Audio RBC-1 remote - $ 54.99
Crutchfield Amp Wiring Kit - $37.49
30-amp Fuses - $3.99
Cable, posi-connectors, rubber spaces, M6 bolts, etc. -<$50.
2x leftover pieces of 8020 Series 10 extruded aluminum.
1x leftover piece of 1/4'' cast acrylic (the kind used to make aquariums)
Some black spray paint
1x can of Sikaflex-252 - $21

The main bracket is designed from 10 Series 8020 aluminum and a piece of 1/4 cast acrylic slotted in the groove. I used Sikaflex-252 to hold the aluminum and acrylic together. It is used in the automotive industry to bond components together, and it has a slight flex to it. The entire bracket is suspended with 1-inch industrial rubber spacers. The bracket is drilled to accept longer M6 bolts that pass through the original subwoofer mounting points. The rubber spacers allow the sub to sit just about ~1.5 inches below the seat but high enough to allow the amp to sit below it.

High end paint booth:

Bracket template:

Layout planning:

Sub comparison to OEM:

I added a on/off switch in case I need it off, and the volume know to adjust the sub output. I just like switches.

The power was connected to this specific bolt on the 12v battery under the seat. It's long enough to accept additional customers. 30amp fuse within ~6 inches..

The power cable was routed along all the other 12v cable going to the back of the vehicle behind the side trim:

The final product:

FAQ:

Q. Why did you use 80/20 and acrylic?
A. It’s what I had around the shop.
Q. It’s an 8’’ sub. Is that big enough?
A. Yes, yes it is. I thought about using a 10-inch. It would fit, but after testing the audio with the 8”, I’m happy with the results.
Q. Any issues with the 12v battery?
A. No issues, no errors.
Q. Did you unplug the battery to plugin the power for the amp?
A. No, wire the switch first to the negative, wire everything else, and turn it on when ready.
Q. Where did you get the audio signal from?
A. The OEM sub wires connect direct to the 250w amp. The amp is configured to auto turn on when it senses a signal.

I did a similar install in my Jeep Wrangler 4xe. I had a god-awful hum from the ANC when it tried to cancel engine/road noise. The negative sound cancelling signal was being amplified by my subwoofer amp causing the obnoxious noise. Solution was to disable ANC but now my jeep doesn't cancel road noise. Did you have a similar problem or does the Rivian not have ANC?

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[ForeverWild]

Interesting. I've always thought a sub needed to be in a fabricated enclosure, sealed or ported.

He’s using it in an open-air application. I’ve done it many times and sounds great with a caveat. You can’t over-power the sub… the sub suspension has to be able to handle the applied power. If he went with 500 watts rms… he probably would have needed an engineered enclosure to provide addition suspension support to the subwoofer cone to prevent fluttering. JL subs can easily handle 250 watts rms.

 

[ForeverWild]

This is a super clean install. Absolutely killer job!

According to the sub specs, ideally it should be mounted in a sealed or ported enclosure with the following specs:

• sealed box volume: 0.3 cubic feet
• ported box volume: 0.35 cubic feet

I'm not sure how many cubic feet the under seat storage area is (with existing driver side tray in place). IIUC, it's "vented" since the opening of where the original 6x9 speaker is still present.

You could have left the 6x9 in place to act as a passive radiator for some woofer cone suspension support. Not needed if you don’t hear fluttering at high volume or deep bass.

 

[ksumnole]

You could have left the 6x9 in place to act as a passive radiator for some woofer cone suspension support. Not needed if you don’t hear fluttering at high volume or deep bass.

Interesting. Thanks for sharing. I did test it at higher volumes and did not hear any fluttering. The sub is set at approximately 65% power. Seems like a sweet spot. Any more then 65% and the vehicle start to vibrate like my OG neighbors 76 el camino.

For what it's worth, the amp is set to:
LP Filter Freq. 80 Hz
Clipping (signal sensitivity) - none
Turn-On Mode - Signal-Sensing
Input Voltage - High
Bass Boost - 0

 

[shracks]

Would you happen to have any pics of the original speaker you pulled? Wondering if we can pull a spec sheet or something if a part number or manufacturer is available. If not, no sweat.

 

[UnsungZero_OldTimeAdMan]

Would you happen to have any pics of the original speaker you pulled? Wondering if we can pull a spec sheet or something if a part number or manufacturer is available. If not, no sweat.

eBay search "Rivian speaker". Some good pictures there. I was going to make a separate post but got busy with work. Most listings are clearly identified as Meridian. The ones that aren't some look like they are indeed the in-house speakers, but look exactly the same as Meridian. The 6x9s look like 2-way units (woofer + mid). But, when Rivian switched to in-house, their published writing made it sound like they removed the mid. So pictures on eBay don't match up to what Rivian published. Unless I am misreading what they wrote (entirely possible).

There are also several listings for the T's sub. Both the sub and the 6x9 door speakers look like they are made of pressed fiber (basically paper pulp). No wonder they distort so easily. This leads me to think of all drivers were replaced with aftermarket ones that are made of better materials (polymer at least), that should yield a significant improvement. But the big question: is the factory amp good enough to drive them?

In addition to swapping the factory 6x9 fiber sub for a poly one, I'm also wondering if adding poly fill inside the enclosure will also help.

Here's a gen 1 Meridian speaker set (including tweeters): https://www.ebay.com/itm/405862654599

Here's a gen 1 non-Meridian speaker (label does not say "Meridian"): https://www.ebay.com/itm/405819318905

Honestly, aside from the labels, they look exactly the same. Made in Vietnam.

 

[UnsungZero_OldTimeAdMan]

You could have left the 6x9 in place to act as a passive radiator for some woofer cone suspension support. Not needed if you don’t hear fluttering at high volume or deep bass.

That would make sense if he repurposed the factory enclosure and mounted that 8" sub to the top of it. Doing so, the amp would have to be mounted elsewhere, like the adjacent storage area. It can't be mounted inside the enclosure. Amps get hot and need airflow and air volume.

 

[ksumnole]

Would you happen to have any pics of the original speaker you pulled? Wondering if we can pull a spec sheet or something if a part number or manufacturer is available. If not, no sweat.

Happy to take some photos tonight.

 

[ksumnole]

That would make sense if he repurposed the factory enclosure and mounted that 8" sub to the top of it. Doing so, the amp would have to be mounted elsewhere, like the adjacent storage area. It can't be mounted inside the enclosure. Amps get hot and need airflow and air volume.

I did think about repurposing the oem enclosure but decided to keep it intact, in case I decide to reverse the setup.

 

[ksumnole]

I did a similar install in my Jeep Wrangler 4xe. I had a god-awful hum from the ANC when it tried to cancel engine/road noise. The negative sound cancelling signal was being amplified by my subwoofer amp causing the obnoxious noise. Solution was to disable ANC but now my jeep doesn't cancel road noise. Did you have a similar problem or does the Rivian not have ANC?

No hum. No anc that I’m aware of.

 

[ksumnole]

That would make sense if he repurposed the factory enclosure and mounted that 8" sub to the top of it. Doing so, the amp would have to be mounted elsewhere, like the adjacent storage area. It can't be mounted inside the enclosure. Amps get hot and need airflow and air volume.

I was thinking of lining the internal space was noise canceling liner. How do you that would impact the sub performance?

 

[ksumnole]

I assume the input to the JL amp is speaker level, not line level?

This is a great mod. IMO it is definitely the way to go. It is on my list as something I might tackle later this year.

Correct, speaker level.

 

[UnsungZero_OldTimeAdMan]

I was thinking of lining the internal space was noise canceling liner. How do you that would impact the sub performance?

Like with Dynamat or equivalent? That should help with vibration and unwanted resonance. Not the same as an enclosure. But better than no liner.

 

[ksumnole]

Like with Dynamat or equivalent? That should help with vibration and unwanted resonance. Not the same as an enclosure. But better than no liner.

Yes, I have a roll of Dynamat I was going to use but ran short on time. I'm going to take the bracket out in the next few days and lay the enclosure with it.

 

[ksumnole]

Would you happen to have any pics of the original speaker you pulled? Wondering if we can pull a spec sheet or something if a part number or manufacturer is available. If not, no sweat.

Photos of the OEM "sub".

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