Sub and amp between middle row seats?

[Foolish]

So, my dear wife has more or less reclaimed her P5, leaving me with the Mazda5 as my daily driver.

In terms of bass, this stock stereo simply will not do. When I had the MPV, even with an upgraded head unit and speakers, the big, boomy box of a van was just too hollow to get any bass sound, and my music all sounded like crap. So, I built a box that fit where the stock sub/amp combo went, put the 8" sub from an MSP in it and put the MSP Kenwood amp under the driver's seat. Worked great, sounded great, made even heavy bass music sound good, but made all music sound better. I kept the sub and amp when I sold the MPV, and plan to install them in the 5 now, but different.

I want to build a box that fits between the middle row's captain's chairs. Ideally, this would hold the sub and amp, though the amp can go elsewhere if need be. I'd like to make it the same height as the seatbacks when they are folded, so that I have a flatter floor throughout, with no hole between the seats. This will also be nice when the dogs are in the car, as they have a tendency to fall in that hole as they move from the middle seats to the cargo area! I'll probably carpet it in black, so it blends in with the rest of the floor/cargo area, and I'd like to build a couple of cup holders into it for my son. I might also like to install an auxiliary power point for his dvd player while I'm at it, so we don't have to run wires to the front or back of the car.

I'll try to keep this thread updated as this project progresses.

 

[Silentnoise713]

Cool. I wonder if you can squeeze in two 8" ? Make sure those cup holders keep the drinks down nice and tight. Also, will this impede access to the 3rd row? When I have the folding cup holds out, it can get in the way of getting back/forth to the 3rd row. I still think relocating the spare tire to under the car (with a full size spare while you're at it) is a possible option. I haven't taken measurements but only visually peeked. I have to remember to do that next time. This will give you the whole spare cavity to play with. I'm just not sure if it will get in the way of a hitch...

Look forward to your build.

 

[JovaBear]

Very curious on how your box will look like in between the middle row. Look forward to your project. Good luck!

 

[Foolish]

Cool. I wonder if you can squeeze in two 8" ?

I only have one! It was plenty in the MPV, I'm sure it will do in the 5.

Also, will this impede access to the 3rd row? When I have the folding cup holds out, it can get in the way of getting back/forth to the 3rd row.

Do you mean that you squeeze between the seats, or just that the folding tray thing gets in the way of the seats sliding? I will definitely be trying to fit this with enough room that the seats can fold and slide without being impeded by the box.

I still think relocating the spare tire to under the car (with a full size spare while you're at it) is a possible option.

WAY more effort than I'm willing to put in to this project!

Look forward to your build.

Me too! Now I just need to find time to work on it! Life, job, kid, dogs, house, etc. seem to be taking up ALL my time lately!


A couple of questions, if anyone reading wants to answer:

1. Is it best to power the amp straight off of the battery? This is what I did with the MPV, and it worked fine, but if it was smarter to run power from a fuse box I could try to do that. Last time, I just used an in-line fuse on the power wire.
2. Where should I tap into the speaker wires for signal?
3. I'd really like to install an auxiliary power outlet on this. Should I use the same power wire as the amp, or run this off the fuse box?

 

[Foolish]

Plotting this out this morning in my mind, I started envisioning making the top surface larger than the console/sub box, so that it filled the space between the folded seats as closely as possible while still allowing room for them to slide. I'm also hoping to build in some kind of storage for my son's DVD case and maybe his DVD player and/or the nifty tablet he's getting for Christmas this year.

I'm thinking of putting the sub at the front of the box, forward-firing, with the amp in a separate chamber near the back so it can ventilate through some rear facing slots. I may add a 12V computer fan to move air across the amp and keep it cool.

I'm getting all kinds of cool ideas, I just need to find the time to start prototyping it in cardboard!

 

[Foolish]

I got in the 5 yesterday and took measurements. The base of this box is going to have to be kind of hourglass shaped, and can only be 6 inches wide in the middle, about 9.5" in the back, and about 10.5" in the front. I know it will be heavy as hell, and I'll probably Velcro it to the carpet, but I'm a bit worried it's going to tip over left and right every time I go around a corner. It won't be very tall, so maybe it won't be a problem, but I don't know.

 

[Silentnoise713]

I only have one! It was plenty in the MPV, I'm sure it will do in the 5.



Do you mean that you squeeze between the seats, or just that the folding tray thing gets in the way of the seats sliding? I will definitely be trying to fit this with enough room that the seats can fold and slide without being impeded by the box.



WAY more effort than I'm willing to put in to this project!



Me too! Now I just need to find time to work on it! Life, job, kid, dogs, house, etc. seem to be taking up ALL my time lately!


A couple of questions, if anyone reading wants to answer:

1. Is it best to power the amp straight off of the battery? This is what I did with the MPV, and it worked fine, but if it was smarter to run power from a fuse box I could try to do that. Last time, I just used an in-line fuse on the power wire.
2. Where should I tap into the speaker wires for signal?
3. I'd really like to install an auxiliary power outlet on this. Should I use the same power wire as the amp, or run this off the fuse box?

The gap between the middle seats is meant to be a pass-thru. When the drink tray is out, this makes it more difficult to walk thru, more like over. Will the length and size of the box block this pass thru? I took a look (no measurement) at the space and think even one 8" sub is going to be a tight fit in due to limited width... Like you said, you may raise the box but if the height exceeds the seat cushions, I think it'll become too obtrusive and out of place; unless you don't need/use that space.

1) Ive never heard of anyone powering their amp from anything other than directly from the battery (or capacitor). Unless you have a weak amp, like an equalizer. How many watt is the amp and what gauge wire are you using for power and ground? I dont think the fuse box has space for a low AWG wire.
2) This depends on where you mount the amp. Do you have an aftermarket radio (the harness would be the obvious choice)? I prefer to tap at a location where all 4 channels are together, so essentially behind the radio.
3) I would use the same power wire, just be sure you have a rely that will close the power source when the car is turned off! But why stop there, integrate an AC/DC converter too

 

[Silentnoise713]

Another though. If you are happy with just one 8" sub, I think you should just save yourself the hassle and get a "beefy" component setup all around with nice sized mids AND a good size 4 channel amp. If you are after base, look at JL, Kicker, RF, type, some are pretty darn cheap now-a-days (but so is quality on some of them). This will improve your overall sound quality and provide added base without taking up interior space. If you are not looking to shake, rattle, and role, there's no need to build a box. Thinking back, having a ported box with two 12" in the trunk was not the smartest thing but it was a learning experience. You really don’t appreciate things like interior volume and trunk space until you have kids.

 

[Foolish]

I think the sub itself will end up being located at the very front of the box, where it can be a bit wider, and faced forward so the flange can be at the widest part of the box.

As far as taking the space between the seats, I'm not worried about it being able to be used as a walk-through. If I had two baby seats in the middle row, plus an older kid who needed to be able to get through to the back, I'd be more concerned, but I've got one kid in a booster seat and two dogs. On the rare occasions that we use the third row, we fold and slide a middle row seat forward for access. The top of the box should be even with the seat backs when folded flat.

Here's a quick MSPaint sketch of what I have in mind. The yellow boxes on the side could be some kind of foam to create a tighter fit between the seats, while allowing the seats to slide forward and back.

 

[Foolish]

Did a little bit of prototyping over lunch today. Just cutting one piece of cardboard for the bottom, I learned a lot! The box can't be hourglass-shaped like it is in the drawing above, the front can't flare back out from the narrow dimension because the "humps" on the insides of the seat will hit it if I slide the seats forward to let someone into the third row. This means that the front of the box will be a maximum of 6 1/4" so the sub can not be forward firing. Fortunately, the rear of the box can still be 8" but I'm not sure what the minimum actual size of the panel can be and still fit my 8" sub. I may have to turn the sub to face one of the sides of the car.

This picture is from behind the second row, facing the front of the car. The second row seats are all the way back and the left one is folded flat.

 

[w2zoom]

ok I want to see this I was thinking of putting a bazzoka in the middle too.

 

[cowdog360]

What about instead putting a single 8" sub in one of the rear compartments and hiding the amp in the tray.

See this for an example:
http://www.cardomain.com/ride/3008760/2006-mazda-mazda5/page-4/

See this for a step by step how to build the actual fiberglass box:
http://www.cardomain.com/ride/2328523/2006-mazda-mazda5/page-3/

That's what I plan on doing.

 

[Gravity]

Ok... First thing I need to point out here and a basic "You can't get around this rule of speaker design": You CANNOT just stuff a speaker (esp a sub) in an arbitrarily sized box and expect it to perform properly.

From the looks of this project, you're designing a sealed enclosure, which does eliminate a lot of the math involved, and pretty much means that the shape will have a negligible impact on the SQ, however if your internal volume isn't calculated properly and/or the box isn't fully sealed (esp where you plan to put those cup holders) then it's a recipe for all kinds of frequency response issues.

You haven't mentioned if the box the driver originally came out of was sealed or ported. If it was sealed, then you're good to carry on... If it was a ported cabinet, then you could run into some issues. I'm assuming that finding the T-S parameters of this driver is going to be neigh on impossible, but the basic idea is that if a speakers Qts value is above or below a certain point (0.54 i believe) it will be suited to either a ported or sealed design.

If it came from a sealed cabinet, you will want to be sure that your new cabinet's internal volume is as close as reasonable (within a few cubic inches) as the previous cabinet. If it is too small, you WILL get weak thin bass that will be very 'tight' or more appropriately it will sound 'choked', in a best case scenario you will find the low end extension is very limited. If the cabinet is too large you will likely end up with ill defined upper bass and a 'tubby' quality. You could run a higher risk of exceeding the speaker's mechanical power handling as well at higher volumes.

It's VERY difficult to establish T-S parameters if they arne't already known/documented. You'd need some relatively expensive software/hardware, but determining the type of cabinet the speaker originally came out of is the best start. If it was ported, you should (at the very least) try and match the box volume(minus the port volume) and the port volume for best results.

 

[cowdog360]

It nice to hear someone actually talk about design parameters. It's funny when I was in high school I built all my own boxes using DOS speaker software to build the box to math the Q values of the subs. I always preferred a sealed box, but once bought a ported box. I tossed out the cardboard tubes inside it thinking they were packing material and wondered for the longest time why the box sounded horrible.. lol.

 

[Nybiomed]

True 'dat!

Silentnoise713: "Another though. If you are happy with just one 8" sub, I think you should just save yourself the hassle and get a "beefy" component setup all around with nice sized mids AND a good size 4 channel amp. If you are after base, look at JL, Kicker, RF, type, some are pretty darn cheap now-a-days (but so is quality on some of them). This will improve your overall sound quality and provide added base without taking up interior space. If you are not looking to shake, rattle, and role, there's no need to build a box. Thinking back, having a ported box with two 12" in the trunk was not the smartest thing but it was a learning experience. You really don’t appreciate things like interior volume and trunk space until you have kids."

I paid an installer $700 to Dynamat my M5, install a 4 channel Kenwwod amp, tint all the windows, and swap out the WEAK OEM 5x7's with better Infinity's- Worth every penny! I recently got an 8" SoundStream amplified subwoofer ($145 shipped) and it fits neatly under the drivers seat pushed towards the seattrack nearest to the door to avoid a wiring harness. I haven't completed the subwoofer install yet, but unless you have a sh!tload of time and are just looking for a learning experience, i'm not really sure the point of all this, but to each his own...

 

[Silentnoise713]

I paid an installer $700 to Dynamat my M5, install a 4 channel Kenwwod amp, tint all the windows, and swap out the WEAK OEM 5x7's with better Infinity's- Worth every penny! I recently got an 8" SoundStream amplified subwoofer ($145 shipped) and it fits neatly under the drivers seat pushed towards the seattrack nearest to the door to avoid a wiring harness. I haven't completed the subwoofer install yet, but unless you have a sh!tload of time and are just looking for a learning experience, i'm not really sure the point of all this, but to each his own...

$700 for all that (parts and labor) is not bad at all but I'm guessing they only dynamat the doors. Where is the amp mounted? I'm very interested in seeing where folks mount their amp and since a shop did this I'm hoping to see a clean low profile install.

 

[Silentnoise713]

ok I want to see this I was thinking of putting a bazzoka in the middle too.

I have a new-used 8" bazzoka tub lying around in the garage (years old but never used). I'll have to remember to test fit it and let you guys know.

 

[Nybiomed]

4ch amp is under....

$700 for all that (parts and labor) is not bad at all but I'm guessing they only dynamat the doors. Where is the amp mounted? I'm very interested in seeing where folks mount their amp and since a shop did this I'm hoping to see a clean low profile install.

...the passengers front seat. $700 was for ALL labor. I paid for the amp, speakers, and Dynamat- actually only half of it was Dynamat, the onther half was "Peal/Seal" stuff from HomeDepot- it really seemed every bit as good/thick as the expensive stuff, but check it, because there was thinner stuff not as good, right next to the stuff I used that was indeed layered with aluminum. Nearly the entire roof, doors- including rear hatch, and spare tire well was covered with it.... Tint and "amp kit" was covered by the $700 tho....
Kenwood amp was $108 from Ebay:

https://www.ebay.com (commissions earned)
- I see this seller has for $126

6 rolls of Peal/Seal from HD was $64- had 1/2 roll of Dynamat left over from previous project

2 sets of Infinity 5x7's were $88 from Amazon

 

[Foolish]

Well, this plan is on hold for now. I'm not sure if we're keeping or selling the 5, and I'm not sure whether I'll be driving it regularly.