Drop In Subwoofer For Coupe Rear Deck (Semi-Custom Bracket)

[JT Si]

Well, after a shit ton of research and a few failed attempts to find a subwoofer that would literally just fit in the coupe rear deck, with the help of @rramrattan I found that the Kicker 44CWCD84 is not only a (tight) drop-in fit in the coupe rear deck, but it also has very good characteristics for open-air/infinite baffle. A generous XMAX of 8.6mm and a total q/qts of 0.767 made it the best possible candidate.

Not to mention it's literally the only subwoofer that will drop into the coupe rear deck with absolutely no modifications.

First, to test and wire it in I soldered a parallel dual voice coil harness into one of the Metra OEM wire adapters. Eureka! The stock amp seems to have enough juice it works.

Due to the absolute lack of clearance between the coupe rear deck and window, even a 90 degree tool to run self tapping screws would not fit. Not to mention I didn't want to permanently modify the rear deck.

Instead, I took my OEM subwoofer (that I busted trying to take the lid off, whoops!) And took off the foam gasket, transferring it to the kicker. Then I removed the lid (again), and evaluated it's use as a mounting adapter.

I took a hacksaw and cut off the lid, so to speak, leaving the circumference with the mounting tabs.

I got out ye olde can of black paint and touched it up to seal the bare metal so it won't rust.

I needed longer screws and spacers to mount this to the top. I happened to have some random spacers and washers that I managed to stack well enough, about 10-10.5mm thick, to get a good mounting pressure to hold the sub in place.

The bolts are M6x1.00, and while I got 30mm they are a little too long. 25mm would be perfect.

I put a 3/4"x1/4" strip of closed cell foam weatherstripping around the bracket to protect the face of the sub mount.

It works!

I then took a bunch of green foam I bought at Joann's and shoved it in around the raised subwoofer mount and in the sheet metal gaps in the rear deck to help seal the front from the rear of the sub.

After a bit more sound testing and sealing up a few more holes in the rear deck, I mounted it for good.

After reinstalling the rear deck and c pillars covers. No rattles! Fantastic.

Looks OEM to me

It's way punchier, much better at deeper bass, and so far no distortion at any volumes I've tested, although I'm sure it's still possible with the OEM amp.

Plenty of gap between my makeshift mount and the rear deck, so no chance of the subwoofer contacting it.

One great benefit of the coupe rear deck being so short is that is is very rigid and has few to no rattles. Even cranking this thing up (limited by the OEM amp, of course) there are absolutely no rattles and no terrible flex of the rear deck. Score one for the coupes.

Enjoy some 480 FPS video showing no discernable flexion in the mount or rear deck.

 

[kimtyson]

Thanks for your work and for posting. Can you please give a little more detail on "I soldered a parallel dual voice coil harness into one of the Metra OEM wire adapters"? I want to add this sub but not sure exactly what that means.
Go coupes!

 

[JT Si]

Thanks for your work and for posting. Can you please give a little more detail on "I soldered a parallel dual voice coil harness into one of the Metra OEM wire adapters"? I want to add this sub but not sure exactly what that means.
Go coupes!

I took one of the Metra OEM speaker plug adapters and cut off the speaker ends, then soldered them to some speaker wire I had laying around to create a harness to connect the dual voice coils in parallel.

The OEM subwoofer is 2 ohm, and the OEM amp is 2 ohm stable which allows it to deliver a bit more power to the subwoofer than the rest of the speakers, which are rated at 4 ohm.

With a dual voice coil subwoofer, you have the option to wire the voice coils in parallel (makes overall resistance 1/2 of the rated resistance), series (makes overall resistance double rated resistance), or wire each voice coil to its own amplifier.

This subwoofer is a 4 ohm dual voice coil. I researched the single voice coil model - it is also 4 ohm which would reduce the amount of power it will get from the OEM amp and it also has less favorable total q/qts for this use case.

Since we want as much power as possible from the OEM amp and the amp is 2 ohm stable, we want to wire the positive terminals together and the negative terminals together.



Positive to positive:

Negative to negative:

 

[kimtyson]

That makes sense. Thanks so much! That's a great help. Anything we can do to improve these weak sound systems is a plus.

 

[JT Si]

That makes sense. Thanks so much! That's a great help. Anything we can do to improve these weak sound systems is a plus.

Don't underestimate how much stuffing the green foam into the raised mount and sealing many of the holes in the rear deck helped.

In my sound testing just adding the foam around the mount helped significantly. The farther away from true free-air you can get it, the better it will sound.

A bit of actual sound deadening will help, too. But the coupe rear deck is so rigid I'm satisfied with my sprinkling here and there.

 

[TripleDeckerPBJ]

Wow this is great! Thank you for making this overview and having to go through the trial and error you may have done. I've wanted to upgrade some speakers for the Si, but haven't really looked into it. This further entices me! Looks great dude

 

[JT Si]

Wow this is great! Thank you for making this overview and having to go through the trial and error you may have done. I've wanted to upgrade some speakers for the Si, but haven't really looked into it. This further entices me! Looks great dude

Thank Crutchfield and Best Buy for generous return policies

 

[thatcaveman]

Amazing. Was it hard getting the lid off the bracket? Was looking into options for a drop in upgrade for the sub and this just might be it.

 

[JT Si]

Amazing. Was it hard getting the lid off the bracket? Was looking into options for a drop in upgrade for the sub and this just might be it.

There is a lot of adhesive, so after you remove the 6 small screws you'll need to carefully pry around the circumference, starting at the locating tab.

The hard part really was hacksawing off the lid with the magnet from the bracket.

Yes, it was a pain in the ass. I laid the lid top side down on a piece of cardboard, laid my hacksaw down on the cardboard, and had someone stand on the magnet while I sawed sideways.

My hacksaw was the perfect height to cut it right at the base of the lid, so I was able to get a pretty darn consistent and straight cut.

If you try to free-hand hacksaw it, it will be a massive pain in the ass. A dremel with a cutting wheel would probably be easier, but if you want to make it nice and flat you'll have to put in some extra work filing. Although the consistency of the cut really is irrelevant.

 

[rramrattan]

It's a beauty! Super clean, OEM looking install!

 

[thatcaveman]

There is a lot of adhesive, so after you remove the 6 small screws you'll need to carefully pry around the circumference, starting at the locating tab.

The hard part really was hacksawing off the lid with the magnet from the bracket.

Yes, it was a pain in the ass. I laid the lid top side down on a piece of cardboard, laid my hacksaw down on the cardboard, and had someone stand on the magnet while I sawed sideways.

My hacksaw was the perfect height to cut it right at the base of the lid, so I was able to get a pretty darn consistent and straight cut.

If you try to free-hand hacksaw it, it will be a massive pain in the ass. A dremel with a cutting wheel would probably be easier, but if you want to make it nice and flat you'll have to put in some extra work filing. Although the consistency of the cut really is irrelevant.

Thanks.

Do you think tin snips would do the trick? I keep wanting to pick up a Dremel, but I'm not sure how often I'd use it outside of this project.

 

[JT Si]

Thanks.

Do you think tin snips would do the trick? I keep wanting to pick up a Dremel, but I'm not sure how often I'd use it outside of this project.

I do not think tin snips would work. Due to the thickness and shape of the stamped steel, I think it would be impractical and possibly bend/destroy the bracket you're trying to make.

 

[Conika]

I took one of the Metra OEM speaker plug adapters and cut off the speaker ends, then soldered them to some speaker wire I had laying around to create a harness to connect the dual voice coils in parallel.

The OEM subwoofer is 2 ohm, and the OEM amp is 2 ohm stable which allows it to deliver a bit more power to the subwoofer than the rest of the speakers, which are rated at 4 ohm.

With a dual voice coil subwoofer, you have the option to wire the voice coils in parallel (makes overall resistance 1/2 of the rated resistance), series (makes overall resistance double rated resistance), or wire each voice coil to its own amplifier.

This subwoofer is a 4 ohm dual voice coil. I researched the single voice coil model - it is also 4 ohm which would reduce the amount of power it will get from the OEM amp and it also has less favorable total q/qts for this use case.

Since we want as much power as possible from the OEM amp and the amp is 2 ohm stable, we want to wire the positive terminals together and the negative terminals together.



Positive to positive:

Negative to negative:

So did you just wire this as 2ohms and then use the metra harness to plug directly into the OEM sub harness? I’m debating on adding a separate amp for mine with this exact sub, or if the factory amp can power this sub set up. I would prefer not having to run wire for an amp if this will work with the factory sub harness and amp.

 

[JT Si]

So did you just wire this as 2ohms and then use the metra harness to plug directly into the OEM sub harness? I’m debating on adding a separate amp for mine with this exact sub, or if the factory amp can power this sub set up. I would prefer not having to run wire for an amp if this will work with the factory sub harness and amp.

Yes, this is plugged directly into the OEM sub harness and powered by the OEM amp.

It's not the tightest or punchiest bass, but I've been able to hear it a lot better than the OEM sub and turn it up a quite a bit louder without any blatant distortion like the OEM subwoofer.

 

[Conika]

Yes, this is plugged directly into the OEM sub harness and powered by the OEM amp.

It's not the tightest or punchiest bass, but I've been able to hear it a lot better than the OEM sub and turn it up a quite a bit louder without any blatant distortion like the OEM subwoofer.

Awesome thanks for the input!

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