My spare tire sub audio build.... need some help!
 

I finally had enough of the terrible stock stereo sooo, here we go!

I plan on adding more detail to this but i have a few questions. Basically Im upgrading my head unit to a Pioneer navigation unit with a backup camera. My speakers are upgraded to the Polk db6501s and I plan to add a slimline 10" sub and amp. Ive built a box that fits into the spare tire and if my calculations are correct, I have 1.5 cu.ft and a mounting depth of 3.5". This is where i need help. I calculated the volume of the sub box by filling it with sand and then using a 6x6x6 box to measure the sand. Well, I counted 3 boxes full, so that would be 1.5 cu.ft., right? ive got pics below....

With the top, the box will sit about 5/8" off the foam top. I plan on adding a carpeted false floor using 1/4" birch plywood and 5/8" mdf(for bracing/raising).

Im not exactly sure how i am going to get enough clearance with a sub grill to remain flush with the rest of the floor....but ill figure it out as i go.

im really ot sure about what sub to get, especially if my calculations were correct with the cu.ft.

also, the amp is TBD as to the sub selection and if i decide to upgrade to Polk mm's :yum:

Any advice is appreciated, hopefully this helps someone else out as well, this is my first custom build with the exception of some simple installs.

I Currently have or have on order:
Headunit
Pioneer AVIC-X930BT Pioneer AVIC-X930BT Navigation receiver at Crutchfield.com
Metra Axxess ASWC Universal Steering Wheel Control Interface
Scosche NN04B 2007-Up Nissan Car Stereo Connector
Pioneer CD-IU51V AV iPod/iPhone Cable for Pioneer AV and Navigation models

Front
Polk db6501 (if theyre blown from using my stock hu, then MMs)

Sub
TBD

Amp
TBD

here are some pics

almost forgot....
I got this..... Color CMOS/CCD 420 TV Lines Car Rear View Camera for Nissan Livina - Tmart.com

and was thinking about this amp kit..... Amazon.com: KnuKonceptz Kolossus 4 Gauge OFC Amplifier Installation Kit: Car Electronics

Math check: A 6x6x6 box is 1/4 of a cubic foot not one half.

thanks guard dad!

I thought something didn't make sense. so, i would have about .75 cubic feet.

i just checked the dimensions:

smaller diameter at the bottom 14" x 2.5"h
portion that covers middle of wheel 8.5" x 1.75"h
larger diameter at the top of the box 16" x 2"h

I did a similar sub and used the Pioneer 10" low profile sub which I was just able to squeeze into the enclosure I made.

I didn't use a grill, I just laid the factory hatch floor panel and carpet over the sub and called it a day. Sounds good too! Just don't through bricks or an anvil on the sub and you are good to go.

Double math check! It's 1/8 cubic foot.

wouldnt 6x6x6 = 1/8 cu.ft? i could fit 8 into a 12x12x12 box.....

if so, that would be 0.125x3= 0.375 cu.ft.??

HA! just posted that!

Bigger would be better but the Panasonic speaker works well in small enclosures. I made the enclosure as large as possible and the walls of the enclosure as thin as possible to maximize volume.

Your enclosure looks shallow, how deep is it in the center?

There's about 3.5" deep including the top

OK-

If you go with a grill the speaker height might not be so critical but keeping crud out of the speaker may be an issue.

If you go with a hidden speaker (my choice) then speaker depth and enclosure depth are critical.

To help minimize the finished height of the enclosure I used a router to hollow out (about 3/8") the back side of the enclosure to create clearance for spare tire anchor-screw and I used a power sander to round off any other points of contact on the back side of the enclosure to allow it to nest into the spare tire as deeply as possible. I had just enough useable room in the enclosure to allow me to recess the speaker about a 1/4" into the top deck of the enclosure. When installed the top deck of the enclosure was even with (maybe a tad above) the factory styrofoam sub deck that rests on the spare tire and creates the floor of the hatch. When installed this way the mounting rim of the speaker stood about 1/4" above the top deck of the enclosure, this was not noticeable with the carpet and trims installed. I also used 1/2" MDF to allow me to better fine tune the final height of the enclosure. 1/2" MDF gives you more precise control of the height of the enclosure than the often used 5/8" or 3/4" MDF but using 1/2" MDF means it takes more layers to build the enclosure.

Pioneer, focal, JL, or kicker slim sub would work here.

I would go focal or kicker.

You do this for a living so you would have way more experience than I but I can say that the Pioneer is only 3" deep, costs about $100, works in a compact enclosure and sounds great for a real-world (good bass but no blown out windows) kind of system.

interesting.....

I think i will go with something like you have GuardDad.

As of now, the top piece of the box sticks almost 5/8" above the top part of the styrofoam deck. I dont mind it being alittle above, especially since i plan on raising the floor at least 1/4" when creating the false floor. Im using 5/8" mdf for most of the box including the top piece which will hold the speaker. If i was able to router down a small portion of the top piece to allow the sub to sit a little more flush, I might be able to use a 5/8" mdf ring to create a speaker grill while allowing enough room for the sub to move(displacement?).

Here is a pic of what i plan on doing, kinda but not as elaborate.....

kudos to butdamnbrian!!!! these are from his audio build and it looks fantastic... good thing my carpet will cover this cause its def not going to look as good.

I was just thinking the same thing.....

BIG, what focal were you recommending? I was looking around and they seem pretty pricey...!!!!!

I was originally considering these....
JLw3 8(assuming theres enough clearance)
Memphis Reference shallow mount 10", 15-mr10d4
Pioneer shallow mount 10, TS-SW250IS4
Kenwood KFC-XW1000F....

That would be my fault, I could of swarn I remember focal doing a slim line sub when I was looking through a magazine last year Hmmm. JL or Kenwood depending on what you want to spend.

Nice setup..

The Pioneer has a pronounced "spacer" ring on the front face of the speaker and the speaker cone is placed such that it really doesn't need front clearance at any semi-reasonable volume level.

At some point it comes down to how much money you want to spend and how much cargo space you need. I think that this approach really rocks considering cost and and cargo space. It makes the factory system sound like a kid's toy. But better systems can be had if you choose to go big and go with sub boxes and multi-channel amps.

Update:

Installed my Pioneer avic-x930bt on Monday. Took close to 8 hrs, and installed the back up camera. When attempting to move the mute wire over one pin to the left on the pioneer harness, i broke the pin :( Now i have no idea what to do to in order to bypass the nav/dvd function while driving..... sux! but at least everything still works....

Anyways, i LOVE the HU so far and my polk db6501s sound much better!

I plan on ordering the ARC XXD4080 and pioneer shallow mount 10" today, everything else is ready!

Im finally almost finished with my build the only thing left is a speaker grill, redo the carbon fiber film and mounting/tuning my amp! oh, and i bought enough dynamat to do the entire car. but thats gonna have to wait a little while. here are some pic. more to come....

Please let me know if you have any questions on the process.

Not bad for a first timer....
oh, and i know the cuts arent perfect. This was all done with a battery powered jigsaw , a drill and some sandpaper. The floor is also in the process of being leveled.

morrrr

How is everybody holding down their enclosures and preventing bumps/thumps?

My intended approach is to use a fabricated "T" bolt which would bolt from the inside (with gasket) and keep the enclosure and the tire together. This has one obvious disadvantage in the event of a flat but some (?) advantages.

Do your subs bump/thump on uneven road surfaces?

I'm starting mine next week ... also using the Pioneer.)

(I think we should form a DIY subclub ... we can have a secret handshake and everything.)

Regards-
Bill

i havent had any issues with the box or false floor moving around. Im silply using industrial velcro to hold the pieces down, they are very light. they box sits pretty snug on the spare tire. I plan on using some dynomat to ensure its in there tight. I dont think it would come out during an accident. The box would first have to come straight up about a foot and only then could it move around freely in the back. The box is the least of my worries if i get in another accident.

oh, and i really thought i would have gotten more feedback on this build. guess it looks like ****

Looks good. Nice and clean

No, your build looks great, its just that you are an Astros fan that delayed my response!

As you know, I am starting my own build ... I'll post pictures of the project as I go along.

I've learned alot from you, Antennahead, mecha1000. jikhead, sigur, chimaera, Guard dad and others attempting the same idea. Many thanks to each of you and others who I may have left out of my acknowledgement.

This build concept is alot more complex than just gluing a bunch of rings together and you're done. Sure, that's one approach but one that doesn't appeal to me. My goal is to advance the overall concept through incremental improvements...

We'll see if I'm successful or not.

Again, a very fine build and thanks for sharing...
Bill

thanks! i appreciate the feedback. this took about 50+ hrs and a 'few' cases of beer to build.

I highly recommend using a router to create the rings. It took forever using a jigsaw!

Alot of the 50+ hrs was just figuring the correct way to do it and making sure the pieces for the false floor joined flush.... lots of sanding!

i should be uploading more pics soon. let me know if you have any questions. I'll help ya out