Fiberglass boxes for 8 inch subs

[randy8876]

Originally I had planned on using my 10's, but they can't fit in the area I chose so I had to re-plan and go with 8's. I'll likely use 8W3v3's, although I've been eyeballing a pair of 8W6's. I don't want to give up any usable trunk space or my cargo organizer. I've just started this project, so bear with me as it's going to progress slowly as I have full time work and college classes.

I had made a fiberglass box for a 10, which I'll probably post up for sale later this month.



Taped up and covered in plastic. I also put up a couple layers aluminum foil. I used a piece of cardboard to give an angle to the base so the box can slip in place without removing the cargo organizer.



I cheat when applying the first layer of fiberglass. I initially use cloth since it's easier to work with. I use spray adhesive to keep it all in place, and after every bit I want covered has cloth over it I paint it with resin. The biggest drawback to this is that the shell doesn't like to pull away. I found by having multiple layers of foil it separates the foil layers and pulls away much easier.



front



back

Time warp ahead a little. These are the back part of the boxes. I've already done a lot of the reinforcing on it. I used chopped mat. Buy a box of 50 disposable gloves for this. Put on 2 pairs and when the outer pair gets torn, melts, or is just too sticky to deal with peal it off and put another pair on. The keeps your hands from getting messed up. And use a respirator- if you're set against it at least do the work outside on a breezy day.


Tomorrow I'll take pictures of them in the car. They sit right on the edge of the cargo organizer. I'll get the mdf rings this week and post as the project progresses. I'm open to any feedback.

[Promise Land]

I want to see these in person when you're done. I smell a road trip for somebody...

[randy8876]

Yeah, once it's all done it will be a good time for a trip. The soundproofing needs to be done this month since I'm driving to Jacksonville, FL in June and July.

I was gonna use JL 8w3's, but I went to the local shop and they didn't sound that impressive. I've decided on the Image Dynamic ID8's, but I have to wait 2 weeks to buy them since everyone is out of stock. The box will be about .4 cubic feet, maybe as big as .5, both are perfect for the ID8. If it doesn't provide enough kick I might be able to port it, but I'll decide after the 2 are up and running.

Here are the shells in the car. I still need to cut them both back some, but when it's finished it should sit about 50% over the edge of the cargo organizer. There's a little gap above the fiberglass which is from the 1/4" thick cardboard I had sitting under it when I made it. I wanted to have some spare room to work with so I could wrap the front glass around and wrap the box in carpet. I might delay doing the front half until I have the subs in my hands to ensure they fit properly.

[08versailles]

Boxes are looking good! More updates!
With two subs facing each other, will there be cancellation issues?
I'm not sure how to describe what I'm talking about.
If you're not happy with results, try one speaker only. Or reversing polarity on one speaker so they drive in the same direction at the same time, not cancelling each other somewhat.
I HAVE NOT TRIED THIS MYSELF! This is why my tidbit of info can be a dangerous thing...

I have an empty 8" box that I will fit someday, and I am very curious how one or two 8" subs will sound in the hatch.
Keep up the good work!

[randy8876]

Boxes are looking good! More updates!
With two subs facing each other, will there be cancellation issues?

I've thought about this also. I'm putting speaker terminal cups so it will be easy to try different wiring arrangements. I'll post on Image Dynamics site and ask them how they think it should be wired. Unfortunately it will be 2 weeks before these can be completed.

[CrankyVersa]

There is no need to worry about cancellation issues here friends.

[randy8876]

I'm dragging me feet on this project, but the subs won't be in for another 10 days so it's not a rush.

I failed to take pictures before laying the fiber glass over the "fleece" (dingy old t-shirt). But here are a couple pictures to show some progress on the passenger side.
Outside the car:


Inside the car:


I know it looks a little rough right now, but it should sand up nicely. I don't know the proper way to avoid resin all over the mdf ring, so I taped it up prior to stretching the fleece over it. The resin should be able to come off with the tape fairly easily. Also prior to stretching the fleece over I sanded inside and a little around the outsides. The roughed up fiberglass of the back half allows the front new part to attach to it a lot better. After it set up and I had a few coats of chopped mat on there I cut away the dowels inside and laid some chopped mat inside where the two pieces meet. I also dumped resin inside and swirled it around the mdf ring to ensure it is completely sealed in there. It's probably overkill, but I've read stories of guys hunting tiny leaks and I hope to avoid that.

Originally I wanted to angle the sub slightly, but I might have had issues with magnet clearance. The sub is just about at a right angle. \Doing it this way also earned me a little more space, so the box should be about .4 ft^3. I'll get some foam peanuts and measure it later this coming week.

[Promise Land]

what are you going to wrap or paint the outside visible surface with?

[randy8876]

what are you going to wrap or paint the outside visible surface with?

Paint is way too labor intensive. I'm leaning towards 4 way stretch vinyl, if I can get a good color match. Or if the surface is too sloppy looking I'll track down some carpet that matches the cargo organizer and use that. I'm not sure which would look better.Carpet tends to allow for a lot of slack in surface quality and pads around the box, but it could look weird.

Here's my original attempt. It holds a 10" but with if the cargo organizer can't be used. I'll probably complete it someday and ebay it.

[randy8876]

Made some progress today.
Here is the mdf ring taped up prior to mounting:

The take helps to keep the seating surface clear of any resin. If someone knows an easier way I'd be happy to hear it.


Here's the ring set in place with dowels.

Pretty basic. Hot glue gun, dowels and something to cut them with. I found it easier to make an estimate of dowel length, cut it and glue it to the mdf ring. Then when you position the ring how you want it you only have to glue one end. The glue flexes enough to allow any positioning of the dowel.


Here it is wrapped in a T shirt:

I used hot glue to hold it in place. Just glue one corner, then go to the opposite corner and work your way around until you have it tight with no creases.

That's all for now, I'll update as the work progresses.

[randy8876]

Here's the first coat of "milkshake" sanded down and covered in black primer. I was surprised how much the black primer matches the interior. I've still got some sanding to do on it.

Here's a little closer with a fresh coat of primer. You can see a little resin got on the seating surface. The primer definitely makes it easier to see all the flaws.

This job will be on hold again until after the 4th.

[randy8876]

I couldn't help myself and had to work on it a little more today. I did the initial sanding and coat of primer on the other side Here's a picture of both in the car:

I'll cover the front in vinyl, the back side I might cover in carpet just so it slides in easy and stops rattles. I'm not sure how I'll fasten either side down yet, although both sides fit in kind of snug and I could probably get away with just setting them in place.

[08versailles]

Looks awesome.
I'm sure with your attention to detail, the result will be outstanding!
How do you feel about an 8 or 10 under the driver's seat?
I might go that way, but never done it, nor seen it done in person.

[Promise Land]

there's not enough room under the seat for a good enclosure.

[randy8876]

Looks awesome.
I'm sure with your attention to detail, the result will be outstanding!
How do you feel about an 8 or 10 under the driver's seat?
I might go that way, but never done it, nor seen it done in person.

t subs

I've read of the idea before, but I see 2 major issues. First off there's not a lot of space, but it *might* be possible to build a very shallow .2-.3 cubic foot enclosure.

The second problem are the shallow mount subs I've heard kind of suck. They have very low excursion (xmax) and thus can't move a lot of air. But, technology can change and somebody might make something. You might also want to look at the passenger side footwell, there might be room there.

On a positive note there is enough room for stuffing amplifiers under the seats. JL has HD and XD models, Alpine has their PDX, Soundstream has Stealth, Arc has their mini's and there are numerous others out there.

If you find a sub that can move air and go low you can put it anywhere and still get the good bass feel, and not be able to determine the location. My subs will handle from 20-70hz, in that range it's pretty much non-directional sound.

[randy8876]

Here's my first attempt at trying to wrap it

The vinyl is the stinger 3 way stretch type. It's more of a PITA than I thought it would be. I used spray adhesive on both the vinyl and enclosure and waited for it to get tacky and then stretched the vinyl on. If you start at the bottom you'll end up with ripples all over the top and the only way to fix it is to tear it off and start over. As I stretched it and glued it in place I ended up with spare material to cut off, which gave me a seam at the bottom.

Also the hotter the vinyl is the easier it is to stretch. After setting it in the sun after the initial gluing I had to re-stretch it, the second one I'll leave the vinyl in the sun prior to gluing it on.

The carpet on the back allows it to slide in nicely, not rattle and seems to make it fit a little tighter.