Another Subwoofer Upgrade Option with pics

[10 green]

i have added this sub according to vipermann and was not impressed with the results. i dont think changing the phase of the woofer does anything in this case. With the port installed there is a of of enclosure vibration. I then removed the port and plugged the hole, better but the enclosure still vibrated horribly, after all it is not very rigid. Next i covered the enclosure in dynamat and wow what a difference, eliminate the vibration and the sub sounds 100x better. If you add any sub to this enclosure you have to Dynamat the whole enclosure

[Vipermann]

i have added this sub according to vipermann and was not impressed with the results. i dont think changing the phase of the woofer does anything in this case. With the port installed there is a of of enclosure vibration. I then removed the port and plugged the hole, better but the enclosure still vibrated horribly, after all it is not very rigid. Next i covered the enclosure in dynamat and wow what a difference, eliminate the vibration and the sub sounds 100x better. If you add any sub to this enclosure you have to Dynamite the whole enclosure

Just saw this. The phase change helped mine, but have to agree that Dynamat also helps.

[viperBase1]

I use the CD Player as a running clock to time the warmup from a cold start. Almost always it's Robin Trower.
After that the Belanger stereo kicks in.

[06SRTCoupe]

You guys are over thinking this. Unless you are going to go full blown with a fully upgraded sound system, just throw an amplified bazooka tube in the back and be done with it. They have their own bass adjustment and add the perfect amount of bass. You can leave the stock system in place (unless you want to change the head unit).

[Creatre]

You guys are over thinking this. Unless you are going to go full blown with a fully upgraded sound system, just throw an amplified bazooka tube in the back and be done with it. They have their own bass adjustment and add the perfect amount of bass. You can leave the stock system in place (unless you want to change the head unit).

Doesn't work on a vert.

[06SRTCoupe]

Doesn't work on a vert.

I'll bet if you snugged that Bazooka Tube right behind the front seats and where the top folds, you would hear it just fine.

If not, the only real effective way, is to install an aftermarket sub in place of the stock one. It would have to be a custom box built with at least an 8 inch sub installed. Yes, you read that right...8 inch. The hole would have to be cut bigger but would be worth it and pretty easy to do. The stock box is junk and should not be used for anything other than the stock sub. Any good stereo shop can do all of this work in a day.

[ck9887]

Guys, I have a Gen 3 Vert with 100% stock sound system.

The factory sub is blown and rattles even with the bass turned all the way down. Can I simply replace this with the kicker or memphis unit to eliminate the awful rattle?

Keep in mind, I'm not looking to add a bunch of bass over the factory unit, I just want to get rid of the obnoxious rattle. I would actually just replace it with another factory sub to keep things simple, but the part is discontinued.

So whats the most simple, easiest route? I don't have an issue lining the factory box with dynamat and spray foam but really don't want to get into modifying much beyond that. And what would be involved with sealing the stock port, if that's what is needed to eliminate rattling?

Thanks

[Creatre]

Guys, I have a Gen 3 Vert with 100% stock sound system.

The factory sub is blown and rattles even with the bass turned all the way down. Can I simply replace this with the kicker or memphis unit to eliminate the awful rattle?

Keep in mind, I'm not looking to add a bunch of bass over the factory unit, I just want to get rid of the obnoxious rattle. I would actually just replace it with another factory sub to keep things simple, but the part is discontinued.

So whats the most simple, easiest route? I don't have an issue lining the factory box with dynamat and spray foam but really don't want to get into modifying much beyond that. And what would be involved with sealing the stock port, if that's what is needed to eliminate rattling?

Thanks

The rattle is just the port tube that has becoming dislodged. Just take out the sub box and secure the port tube with some polyfill or something and put it back in and I bet it'll be fine. I would not recommend going through the effort to put in an aftermarket sub, I have not been impressed with mine.

[ck9887]

The rattle is just the port tube that has becoming dislodged. Just take out the sub box and secure the port tube with some polyfill or something and put it back in and I bet it'll be fine. I would not recommend going through the effort to put in an aftermarket sub, I have not been impressed with mine.

Thanks! I will give that a shot this weekend. Might add some dynamat to the stock setup for extra measure.

[Wd40]

Question.. if you have a coupe and throw a 10” sub in the back could you just replace the 6.5” sub for a speaker?

[Creatre]

Question.. if you have a coupe and throw a 10” sub in the back could you just replace the 6.5” sub for a speaker?

Yes, if you have an aftermarket setup that can send that speaker full range rather than just low-range signal.

[Ameration]

Resurrecting an old thread, but what is the depth of the stock 6.5” sub box? I need to do something as the 14+ year old stock speakers in the 2006 that I just bought are horrible.

Thanks.

[Steve M]

I don't remember exactly, but I was able to fit a CDT Audio M6+ in mine with a 1/4" MDF spacer. Mounting depth on that speaker is 3.37", so realistically, you have between 3.0-3.125" before you'll have interference issues.

I've said it before, and I'll say it again - don't put too much time and effort into the stock sub box. It is in a bad location, and physically can't move enough air to make a difference. I can crank mine up as high as I'd like, but at only moderate volume, it starts rattling everything around it. I've switched mine to mid-bass duties, and even that is asking too much of it.

[E.Murray]

Steve is right. My car came with a Kicker in the spot that sounded atrocious. I pulled it out, deadened the box and surrounding panels, fixed all the little air leaks and managed to get it to merely bad sounding. At moderate levels, it actually sounded decent. But when I turned it up at all, there was enough rattling and distortion that whole system sounded bad. And I have a very nice sound system otherwise. I gave up a couple weeks ago and designed a little box with 2 6.5" Peerless speakers and 2 8" passive radiators that fits in the passenger footwell. Now, the whole system sounds like I want. It thumps so hard that you don't want to turn it up with the top up. And even on the highway, you can hear and feel the music (over the Belanger pipes...). I, personally, really dislike footwell subs, but there's just no other option if you want to enjoy your music.

[Steve M]

I, personally, really dislike footwell subs, but there's just no other option if you want to enjoy your music.

That's about all you can do with a convertible.

The cabin gain you get with a coupe makes it really easy to get big bass without a ton of effort. ~350 watts to a single 10" in a sealed box in mine gives me more than enough bass. Once you make the jump to a real subwoofer, you quickly realize what you were missing all along, and you just can't reproduce it any other way. You have to be able to move the air.

[E.Murray]

You have to be able to move the air.

Yep. A 6.5" will never do what a halfway decent 10" can do. The amount of air moved is related to the area moved (whether it be sub, port, or passive radiator) and the stroke of the movement. The benefit the stock design has is location, which often gets overlooked. As a way of comparison, doubling the power gets you a 3dB gain in SPL. Doubling cone area does the same thing. So two drivers on double the power gets a 6dB gain. But sound falls off at 6dB for every doubling of distance. So putting two drivers on double the power at twice the distance nets you nothing. I'm guessing that Dodge decided that a small sub in a small enclosure right at your elbow would be good enough. And it's not terrible (despite what I and others have griped about). IF (and that's the rub) it produces clean sound and can handle power. But when you have power-handling issues and other things nearby that rattle (remember that the SPL gain/drop can work against you for nearby rattles), it isn't a great solution. I'm an acoustic engineer with Dolby, so I appreciate what they were working with. The enclosure is actually an engineering feat. Tuning that low in only that much space is not an easy thing. That, incidentally, is the reason nobody has really improved anything in the stock location. The designers maxed the capability. The fact that no easy solution exists is a testament to the design. But it still sucks.
For me, it took a lot of work to get a design that would fit two long-stroke subs and 2 8" passives in the footwell. I'm using every last cubic mm. The end result is more air moved than a typical 10" sub without too much loss in footroom. But it's still a compromise. If you want louder, there are lots of ways to get that. I'm using a 4 channel amp, a dsp, and top-quality components in the stock door and dash locations and can easily hear the stereo on the interstate with the top down. But if you want solid bass at the same time, I don't see how you'll get it without moving more air than the little 6.5" will be able to do.

[Steve M]

Yep. A 6.5" will never do what a halfway decent 10" can do. The amount of air moved is related to the area moved (whether it be sub, port, or passive radiator) and the stroke of the movement. The benefit the stock design has is location, which often gets overlooked. As a way of comparison, doubling the power gets you a 3dB gain in SPL. Doubling cone area does the same thing. So two drivers on double the power gets a 6dB gain. But sound falls off at 6dB for every doubling of distance. So putting two drivers on double the power at twice the distance nets you nothing. I'm guessing that Dodge decided that a small sub in a small enclosure right at your elbow would be good enough. And it's not terrible (despite what I and others have griped about). IF (and that's the rub) it produces clean sound and can handle power. But when you have power-handling issues and other things nearby that rattle (remember that the SPL gain/drop can work against you for nearby rattles), it isn't a great solution. I'm an acoustic engineer with Dolby, so I appreciate what they were working with. The enclosure is actually an engineering feat. Tuning that low in only that much space is not an easy thing. That, incidentally, is the reason nobody has really improved anything in the stock location. The designers maxed the capability. The fact that no easy solution exists is a testament to the design. But it still sucks.
For me, it took a lot of work to get a design that would fit two long-stroke subs and 2 8" passives in the footwell. I'm using every last cubic mm. The end result is more air moved than a typical 10" sub without too much loss in footroom. But it's still a compromise. If you want louder, there are lots of ways to get that. I'm using a 4 channel amp, a dsp, and top-quality components in the stock door and dash locations and can easily hear the stereo on the interstate with the top down. But if you want solid bass at the same time, I don't see how you'll get it without moving more air than the little 6.5" will be able to do.

You make some very good points.

I'm an engineer, but certainly not in anything related to sound. I've taken an interest over the last decade or so in car audio, but only as a hobby. I started fabricating my own subwoofer boxes over the past year, and I'd really like to know more about how to better design one, also keeping in mind that available vehicle space tends to trump everything, at least for the vehicles I currently own.

I'd love to see pics of what you did, and details of how it works. It sounds like a very cool design, and I'd like to know more about it.

[E.Murray]

I still need to wrap it and finish the grille, but here it is "in process." I pulled a fiberglass mold of the floor to start with, then added the MDF baffles. It's definitely odd looking... The two drivers in the front are the Peerless SLS 6.5" wired in parallel. They're getting 300W from a tiny NVX amp under the seat (the amp layout is also an in process picture). The top and side have Dayton 8" passive radiators since there's no good way to add a port (a passive radiator does the same thing as a port if you're not familiar with them). The top one is angled to clear a connector under the dash (which is centered in the cone) and to give enough room on the right for the other passive. The passive on the right is about an inch from the wall. Putting them in this configuration gives them a little front loading to assist with lowering the tuning. I had to add 120g to each of them to get the tuning where I want.
I expected the performance to be decent, but had no idea it would be so crazy. It's enough in the 40-80Hz range with no boost and EQ set flat that it thumps your whole body with the top up. My theory is that there are two things helping it out. First, that flat floor pan has a real tendency to resonate, so I think it acts like a big passive resonator in that frequency range. Second, filling that area at the base of the footwell leads to a big "horn" shape between the glovebox and floor. A big horn is a great way to boost output, but usually isn't practical. A horn helps with impedance matching between the driver and the air outside the box. While the shape isn't ideal, I think we get some horn benefit from the gradual expansion of the volume from the woofer face to the seat. Either way, I'm pretty happy with the result. Now I just have to settle on a grille setup so it doesn't get kicked when my 6' 2" son rides in the passenger's seat...Viper sub.jpgIMG_1002.jpg

[Steve M]

That is a very interesting design...time to do some more reading.

I don't think I need anything more than I have with a single 10" in a sealed box in my hatch, but I'm always up for experiments, and this sounds fascinating.

[E.Murray]

All of the design work was really just to get me to something close to what you have. If I had a coupe, I'd do exactly what you did. Weeeelllll, maybe a ported box (depending on the sub). But, otherwise, skip the silly footwell box and just do something in the hatch as it should be. All the fancy garbage is just to try to get performance that could be had much cheaper and easier with a standard design. The standard designs really are better in every way. We only use the stuff I used if we have absolutely no other choice.
Honestly, if I could have afforded a coupe, I would have bought one and never looked back. Superior looks and better usability. But there were none to be found in my budget (that didn't have a ton of miles and a rebuilt title). So a convertible it was. And in 60-something different cars, I can say that I've never had more fun. These things are a complete and utter hoot. But a great stereo makes life better, always.

[Steve M]

I may try a box with a couple of passive radiators just to see what it does...yeah, they aren't super cheap, but I like science projects. Bonus points if they actually work worth a damn.

What frequency did you tune for? And how do you decide on mass when using two radiators? Do you calculate what you need if you only had one, then make sure each has half?

[E.Murray]

I may try a box with a couple of passive radiators just to see what it does...yeah, they aren't super cheap, but I like science projects. Bonus points if they actually work worth a damn.

What frequency did you tune for? And how do you decide on mass when using two radiators? Do you calculate what you need if you only had one, then make sure each has half?

Uh oh. You're standing on the edge of the rabbit hole. Back slowly away.
Kidding. It's actually lots of fun and not hard. I'm a mechanical engineer, too, and love these kinds of things. Download Winisd and kiss the next week of your life goodbye. You enter some numbers called Thiele-Small parameters in for a given sub, then can play with box size, tuning, and power. It's a game of balancing SPL and cone excursion (to stay within the limits of a given sub). In a sealed box, you just plug in your power and adjust box size, keeping an eye on cone excursion.
In a ported box, you have an extra bit of freedom using the box tuning. You can adjust box size and tuning to get the best output given your power and sub. The catch is that you need to keep an eye on air velocity in the port as well as cone excursion. Get close to 25-30 m/s in air velocity and you'll have a port that makes annoying noise. To affect the air velocity, you change port area and length. A bigger port area drops air velocity (which is good), but requires a longer port (meaning the box gets bigger). It's a little more complicated, but can give way better results than a sealed box once you balance everything.
A passive radiator setup is both simpler and more expensive than a port. A passive is, acoustically, just a port you can adjust. In Winisd, you enter the Thiele-Small parameters for the bare passive radiator you're using and can add weight to see how tuning is affected. It's nice because you don't have to worry about air velocity and can use a smaller box (because you don't need all the port volume). But they are a challenge because you need roughly double the air movement. That means if you have a 10" sub with 12mm of xmax (i.e. travel in one direction), you either need two 10" passive radiators with 12mm of xmax or one 10" that has 24mm of xmax. That's why my design has 6.5" drivers (which I'm limiting to 9mm of travel with the power) and 8" passive radiators with 11mm xmax.
It looks a little overwhelming at first, but if you spend a little time in some basic research, you end up with a solid enough working knowledge to make measurable improvements in stereo work that don't actually cost any more time/effort than a mediocre design. In my opinion, if you plan to do any stereo work at all, it's worth the couple hours of learning curve.
And I think I officially hijacked the thread. What were we supposed to be talking about again?

[Steve M]

Well, the title says "Another Subwoofer Upgrade Option", and I'd consider this another upgrade option.

I'm going to start playing around with that software, and see what I can come up with. The box design currently in the car should have enough room to accommodate two of the Dayton 10" passive radiators, but they'll be the pricier ones since my current sub has a 17mm one-way Xmax. Thankfully, Parts Express is about 20 minutes away from my house. Based on what I've read so far, the current sub might be borderline with its Qts of .35, but I'll at least run the calculations and see how it might fare.

I'm not too worried about fabricating a decent box at this point - I have a reasonable table saw, and a router table with a lift that makes things fairly straightforward. A nice circle cutting jig really helps too.

Here's to another science project...my wife will be so thrilled.