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Upgrading stock subwoofer

Flux

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Okay, there's lot's of things I'm good at (this is up for debate), but stereos and electronics aren't one of them although I can follow instructions. Sometimes.
I have a 2020 JT Rube with the 8.4" screen and premium audio (not the Alpine). This system came with a subwoofer behind the rear seats as well as the BT speaker (irrelevant to my conundrum). I could swear I found a thread previously about upgrading the stock sub with a better one in the SAME location. Under seat is already full of gear........ Anyhow, I've searched and searched but am coming up empty. Has anyone done this? Was it fairly easy to integrate with factory stereo?
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I went down this path and couldn't find a suitable speaker that would fit AND be an improvement over OEM. I ended up building a box for two 10's to sit behind the rear seat. I used the Kicker Comp RT shallow 10's.
 
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Thank you for the recommendation!
 

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the issues you encounter with the OEM box are that its very shallow, especially towards the top of the subwoofer....This is easy to overcome. The main problem is that the subwoofers that are shallow enough to fit but also handle more power wont fit the diameter of the cutout.

Im in the process of designing a box to fit the OEM space but also take a shallow mount kicker 10. (the one mentioned in the previous post above). There is enough space to build a sealed enclosure in that space to house a 10" an 8" or maybe even two 6".
 

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the issues you encounter with the OEM box are that its very shallow, especially towards the top of the subwoofer....This is easy to overcome. The main problem is that the subwoofers that are shallow enough to fit but also handle more power wont fit the diameter of the cutout.

Im in the process of designing a box to fit the OEM space but also take a shallow mount kicker 10. (the one mentioned in the previous post above). There is enough space to build a sealed enclosure in that space to house a 10" an 8" or maybe even two 6".
Are you guys using any speaker designing software taking into account the speaker electrical and acoustical parameters to get the right box size and shape? Even after that the box usually needs to be tuned by adding or removing fluffy stuffing. If you just stick a random speaker in a random box you will probably not be happy with the sound.
 

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Are you guys using any speaker designing software taking into account the speaker electrical and acoustical parameters to get the right box size and shape? Even after that the box usually needs to be tuned by adding or removing fluffy stuffing. If you just stick a random speaker in a random box you will probably not be happy with the sound.
with a sealed box, volume is most important. If it’s ported, you’re right but there’s really not enough room to go ported behind the backseat.
 

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Normally I would use software or plain old geometry to design my box. However, I am working on designing a box that fits in the OEM space so everything looks factory.... this dictates my shape and port design if I go that route.
I can probably design a ported box for an 8 inch, definitely a 6.5 pair.

Right now I'm leaning towards a sealed 10 inch enclosure since I have more than enough power from the amp to drive a 10 well..

for a sealed box, the shape matters much less because the sealed enclosure functions primarily as a spring/cushion for the back of the speaker. As long is the volume is within manufacture specs, the cushion will be correct regardless of the shape.

A port must be properly sized because it will then provide either too loose or too firm a spring for the speaker and thus damage it.

Ported boxes are great with trying to maximize efficiency and get more bass/sound from a smaller speaker.... frequency range is not usually as good though.

sealed enclosure usually has a much better frequency rolloff and provides a wider range with better response. My set up will put about 350 W to a 10 designed for up to 400 rms.
 

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Normally I would use software or plain old geometry to design my box. However, I am working on designing a box that fits in the OEM space so everything looks factory.... this dictates my shape and port design if I go that route.
I can probably design a ported box for an 8 inch, definitely a 6.5 pair.

Right now I'm leaning towards a sealed 10 inch enclosure since I have more than enough power from the amp to drive a 10 well..

for a sealed box, the shape matters much less because the sealed enclosure functions primarily as a spring/cushion for the back of the speaker. As long is the volume is within manufacture specs, the cushion will be correct regardless of the shape.

A port must be properly sized because it will then provide either too loose or too firm a spring for the speaker and thus damage it.

Ported boxes are great with trying to maximize efficiency and get more bass/sound from a smaller speaker.... frequency range is not usually as good though.

sealed enclosure usually has a much better frequency rolloff and provides a wider range with better response. My set up will put about 350 W to a 10 designed for up to 400 rms.
I've built a number of speaker systems for home stereo and the last one took about 2yrs to peak and tune properly. There are preferable shapes for the sealed box and a sloping front like the stock sub is preferred to reduce internal reflections. Car stereo is not as critical and home use but I've heard a number of car subs that sounded really bad because of size restrictions and no thought put into them.

One thing that helps is to tune the sealed box by changing the amount of stuffing and the way I was taught was to briefly connect a 1.5 volt battery then reverse it going for the exact same clicking sound for both polarities. When you start it might be tick/boom or boom/tick and when the box is tuned it will go tick/tick on both polarities. The resulting sound will be full and tight instead of boomy or tubby. I suspect the stock sub may not be tuned properly but I'm a bit to lazy to take it all apart for testing.

The guy that helped me design my last major speaker project and taught me how to tune the box was Albert Von Schweikert, you might look him up, although he passed away recently.
 

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I’m planning on putting a JL 13tw5 in my stock location… i have figured that i can get around .5-.6 cu ft airspace which would be perfect for that sub… yes power is needed but I’m not going small on my system… but for now I’m keeping stock.
Ps… I haven’t pulled off the panels yet just pre thinking
 

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I've built a number of speaker systems for home stereo and the last one took about 2yrs to peak and tune properly. There are preferable shapes for the sealed box and a sloping front like the stock sub is preferred to reduce internal reflections. Car stereo is not as critical and home use but I've heard a number of car subs that sounded really bad because of size restrictions and no thought put into them.

One thing that helps is to tune the sealed box by changing the amount of stuffing and the way I was taught was to briefly connect a 1.5 volt battery then reverse it going for the exact same clicking sound for both polarities. When you start it might be tick/boom or boom/tick and when the box is tuned it will go tick/tick on both polarities. The resulting sound will be full and tight instead of boomy or tubby. I suspect the stock sub may not be tuned properly but I'm a bit to lazy to take it all apart for testing.

The guy that helped me design my last major speaker project and taught me how to tune the box was Albert Von Schweikert, you might look him up, although he passed away recently.
I've heard of the battery technique but never used. Maybe ill try. I always just stuffed it, listened and put more or removed depending on what I heard from a song I know well.

I agree with what you said above. Most of this issue is the space.....Im essentially replicating the oem box, just altering the face a bit for my needs. Im hoping to improve sound with slightly better interior design shape and by using wood (and a much better speaker)....My main constraint is the outside shape. it must fit under the factory panel. Otherwise, I would have selected different subs/design completely.

I also thought about using a JLw3, the problem is the depth at the top of the box where the internal depth is a little less than 2". the only way Ive managed to fit any speaker the handles north of 300 watts in there is by using a spacer ring I cut with my dremel....I wasn't thrilled with how thick a ring I would need. It also brought the speaker very close to the factory trim panel at the top. This is why Im trying to build my own version now....even doing this I may still need to downsize to an 8" to get the power levels I want and keep it behind the factory panel
 

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blau iii

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I’m planning on putting a JL 13tw5 in my stock location… i have figured that i can get around .5-.6 cu ft airspace which would be perfect for that sub… yes power is needed but I’m not going small on my system… but for now I’m keeping stock.
Ps… I haven’t pulled off the panels yet just pre thinking
That was my origional plan as well but it's too tall for the space. The space from the floor to the lip of the panel is a hair over 12" if you ignore the lip, there is 18" or so but it's far too narrow at the top. I hope you're more creative than me and can figure it out but thought I'd give you a heads up that I tried finding a way to make that sub work and couldn't.
 

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That was my origional plan as well but it's too tall for the space. The space from the floor to the lip of the panel is a hair over 12" if you ignore the lip, there is 18" or so but it's far too narrow at the top. I hope you're more creative than me and can figure it out but thought I'd give you a heads up that I tried finding a way to make that sub work and couldn't.
If you give up the storage space under the rear seats there is a lot of room, although kind of flat. How bout dual subs in a flat box that vent out through cutouts in the plastic trim under the seats? The subs would probably have to be inside the box facing up into the seats but the back pressure could be vented as the main blast. You just have to be careful about the sound from the front of the cones going a different direction than the back pressure so they don't cancel each other.

Or you might be able to angle a pair of 8" inside a flat box under the rear seats so you have a sealed box behind them and the angled fronts point out through cutouts in the plastic trim below the rear seats. The front of the box could be horn shaped to force the sound out the trim cutouts. This is something that could be modeled for correct size sealed box and other parameters.
 

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That was my origional plan as well but it's too tall for the space. The space from the floor to the lip of the panel is a hair over 12" if you ignore the lip, there is 18" or so but it's far too narrow at the top. I hope you're more creative than me and can figure it out but thought I'd give you a heads up that I tried finding a way to make that sub work and couldn't.

I agree. I have torn apart the back and mocked up a couple of boxes. The 13tw5 is extremely shallow, but a box tall enough to house it would still be too narrow at the top to mount the woofer. Even a shallow 12" would be a challenge. The seat back really encroaches on your space as the enclosure height increases. A box taller than 12 inches leaves you with no real depth across the top of the enclosure..
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