My Box idea for 2 8"s...

[chuyler1]

Ok...so my ID8v3s came in last week and its time to begin planning for the hatch. I've got two MTX amps (both 9"x9") and a Stinger Capacitor ( 3.75x3.75x14 i think) that will also be going in the hatch of my P5.

I am going to attempt a ported enclosure using the flex ports sold at www.selectproducts.com. These subs only need about 1cuft to be tuned down to 30Hz so my plan is to build a false floor that serves as an amp rack AND a subwoofer enclosure. It will be about 4-5" thick to allow the amps to be resessed. I haven't worked out the dimensions yet but stop me if you think this is a bad idea. Since the subs require more mounting depth than any of the other components, I am thinking about having them protrude from the floor at an angle.

This is where you come in with opinions. Should I put the subs in the back corners of the hatch (as you look in) and have them face the hatch door (so they are displayed nicely when you open it). Or should I have the subs in the near corners and fire towards the front of the car. The first option will place them out of the way when I get groceries and what not but they will be in the way if I fold down the seats. The second option will be in the most used portion of the hatch (where I just toss stuff in), they would fire towards the front (not sure if this is better than the first option), and they would be out of the way should I fold down the seats to put something big in.

To describe this better, see my 30 second mspaint drawing that is attached. Those of you with P5s will quickly recognize the shape of the hatch. For those of you who don't, the top is the far side of the hatch and the bottom is the near side (or the rear bumper). The amps will be in an oval shaped tub, one on each side and the cap in the center. A pods will be triangular while conforming to the oval shape along the hypoteneus. Each one will have an 8" sub and a 2" port.

As seen in the picture, the pods and the oval trim panel for the amps will be painted silver to match the stock P5 interior trim. The rest of the hatch floor will be a single 1/4" piece of mdf covered in black vinyl. I will have an oval cover for the amps and I will make a carpet to cover the whole thing.

So whadda ya think? Which option in the photo will work best?

For symmetry purposes, I may use the remaining corners for the component crossovers...but since I haven't decided on those...that may come at a later date.

 

[Poseur]

I'm thinking option 1 would look cooler, and likely sound better (rear-firing seems to be the best setup in our cars) 'course it all depends on how often you fold your seats down. Plus avoiding the asymmetrical rear might make it look more balanced as well. Far's raising your floor thatmuch... I know that when I removed my stock sub and all of it's attached crap, I was astounded by howmuch space I gained, and that was only 3-4ish inches. Maybe you could make a "bubble" or something for your amps? Or perhaps do them towards the rear of the hatch, and sorta slope the floor up to them? I've toyed with the idea a bit myself, but it just Seems like alot of wasted space just to get amps to sit flush. I might do it if I ever felt like ditching my spare, but with biking and boarding and such, I'm up in the middle of nowhere too often to risk getting stranded.

 

[MisterT]

Have them firing towards the rear hatch area for best bass response. So the bottom picture would be the best if that is what represents the 8 and the port. Sounds like it is going to look really nice. Please post pics when done. I would like to see how it turns out!

 

[chuyler1]

Well, the thing about wasted space when I raise the floor is...there will be none. The amps are only 2" tall so I only need a maximum of 4" (if you include the height of the MDF they will be mounted to). As for the rest of the space around them...it will be air space for the subwoofers.

Think about how big a 1.2-2 cuft box would be in your trunk...roughly a sealed box for 2 10"s. Then imagine it not being there but still getting the sound of 2 10"s...Thats my goal...I will be sacrificng the space...but without a huge honkin box in the hatch.

Our hatch is about 40"x33" if you square it off. Take the amps out of the equation for now and say I raised the floor 5" using 3/4" MDF. That gives me an internal airspace of 38.5"x31.5"x3.5" which works out to be 2.5cuft. That is definatly a useable number seeing as I can port my 8"s at 30Hz with 1.8cuft, 34Hz with 1.2cuft, or 36hz with 1.0cuft. I could drop down to a 4" floor if I went with a 36Hz enclosure.

 

[Poseur]

Ah, alright, gotya. That should be pretty damn cool. I was thinking you were planning on having the volume coming form the "bubbles" for the speakers. Fully understand now. That should be pretty damn sweet man.

 

[sam1]

i vote for option 1. i think that would look the best. and you could still use most of your hatch, and if you do it right you could still fold your seat down without those getting in the way too much. also, maybe you could use your spare tire area to get the airspace youre looking for.

 

[sndsgood]

i'll go with option 2, it appeats that it will take up less space. if u get them in the corners far enough it really should't eat into mouch of your useable trunk space, and should give u the best bass, with the sub all the way to the back bumper firing forward you won't have any of the cancellation normally associated with a forward firing sub. and the bass will have allot less coloration from reflections normally associated with a rear firing sub.

 

[chuyler1]

Hmm...I knew this was going to be a tough decision.

Well, using the spare tire well is out because I need a spare....The whole thing should be able to lift up for somewhat easy access.

Option 2 will also be less symmetric because that part of the trunk isn't symmetric. One sub will be tucked in the corner while the other will be out in the open...If I try to line them up with the oval amp rack, I will be wasting more space than option 1...and they will be using more usable trunk space when the seats are up unlike option 1 which uses the space that a tall square box will not fit because of the angle of the seats.

However, you have a good point about cancelation with option 1. However, option 2 the woofers will fire into the headliner (asuming the hatch cover is not there) while option 1 will fire into the rear glass and reflect right towards the front of the car...

Its a tough call...I've got a week or so to think about it before I actually start so more opinions are welcome.

 

[sam1]

decisions, decisions=) gotta love it. and who says you need a spare? you could always throw it in the back seat=). j/k

 

[chuyler1]

I've only gotten a flat once in my life...but Murphy's Law states that the first road trip I take after I remove the spare will be my second flat...and it will suck.

 

[Rider69]

I have had two in my life...the second was not long after I removed my spare in the P5 for the stereo install. Good thing I was not too far from home!

 

[sndsgood]

make it symetrical. add a hidden hinge so you can slide the one sub out and get to a hidden compartment behind it


as for the reflections option 1 will be absorbed by the headliner as well. may not be a direct hit but it will effect the sound close to the same. build a mock up box and try them in both positions first to see wich one sounds best.

 

[Poseur]

Wouldn't alot of those cancellation/absorption isues be negated by the porting? Where are you planning on running the ports? and how are the ports gonna be separated from th Flat low box? (seemslike that kind of airspace might work to interfere with your porting...)

 

[chuyler1]

I will use flex-ports that can bend. They will be right next to the subs (see the diagram in my first post -- the small circles are the ports) and will bend so they extend along the bottom of the box. This is another reason why the floor needs to be at least 4" high. I should prolly order the ports now so I have them when I'm ready to start.

 

[sndsgood]

what about porting them out the back straight up to the rear deck?

 

[chuyler1]

umm...well, the P5 doesn't have a rear deck and the ports only have to be about 12" long...but I have always been told that you will minimize cancelation by placing the port on the same plane as the woofer....is this wrong?

 

[sndsgood]

not really wrong, there is a chance of more cancellation, but id think the gain you got from bouncing the port off the rear window would make up for it. i guess you are right though about not having a standard rear deck in those things.