Ram 1500 Cheap Subwoofer "Upgrade"

[BulldogGK]

As a result of the discussion in this post (2021 Missing Subwoofer?), I decided to try to build a new under-seat subwoofer box for my 2021 Ram 1500 to get better sound from the factory speaker.

Let's get this out of the way up front: I am not an audio guy, let alone an audiophile. Of course I know I can get better sound if I got a different sub (especially compared to this 3-voice coil oddball speaker that Alpine made for Ram!), but that wasn't the point.

My goals were simple:

1. Get a better approximation of the factory sub that came with my previous truck - a 2022 Ram 2500 that was under the rear passenger seat. (Yeah, I downsized.) That system was also a 9-speaker Alpine system, but the sub sounded/felt different, partly because of where it was mounted, and partly because the box in this 1500 is SUPER SMALL.
2. Simple. No wiring needed. This build uses the existing amp and speaker, and doesn't even require you to extend the factory cable.
3. Reversible. No permanent changes are needed.
4. Preserve all factory features. I like ANC. I didn't want to disable it or bypass things.
5. Cheap. The original sub was "fine". I just wanted it to be a bit punchier. I already had the plywood, so the only thing I ended up buying was the black felt carpet that I eventually covered the box with.

We good?

Here's the process:

Using 1/2" baltic birch plywood (you only need about a 3'x3' sheet), I was able to make a box that is about .44 cubic feet, which seems like a significant improvement over the tiny enclosure sandwhiched between the seat back and the inner wall. (SketchUp plans are here.)

Some notes on the build:

• The box is easy enough to make with a table saw, jigsaw, and/or circular saw. You'll need a jigsaw to cut out the speaker hole.
• All joints are glued and nailed, and the inside of each corner in the box is caulked.
• I put in some poly fill (maybe 1/4 to 1/3 of a 1lb bag), but kept the area where the speaker would be pretty open. I used a bit of spray glue on the walls of the box just to help keep it anchored inside, but that's probably not necessary. (I put the rest of the poly fill in an old pillowcase and used it to fill the void where the old sub was.)
• You'll need a hole in the top piece that's 8-1/4" diameter for the speaker. There will need to be a notch in the circle you cut out to make room for an alignment pin (or just cut off the alignment pin).
• Before you put the top on, place a bead of caulk around the top of the box so that the top makes a nice, air-tight seal, then attach the top however you want. I used brad nails.
• I covered the sub box in black felt speaker carpet (that's what I searched on Amazon for). It was about $20.

Removing the original sub is easy:

• Fold the rear passenger seat down and remove the plastic fastener.
• Carefully pull the liner off the back.
• There are two 13mm screws that need removed.
• Under the seat, and under the "foot" of the factory sub box (covered in carpet...it almost looks like a vent), there are two more 10mm screws. Remove those.
• Carefully disconnect the wire.
• The sub pulls out from the top, and it might take a bit of wiggling.

After taking out the sub, carefully unscrew the speaker and dislodge the wire. The harness seems really tightly mounted to the black sub enclosure. Mine broke when trying to remove it, but only the mount. It was still usable. Just be careful here.

Installation:

• Install the speaker into the new box, taking care that the wires point towards the back / right.
• Installing in to the truck is easy enough. Set the box in and route the speaker wire under the black backing, then connect the wires and fold up the seat.

I was really happy with the results, and there was more punch in the bass. It's still a bit muddy because of this oddball, jack-of-all-trades, three-coil speaker, but it's much better than before.