I have a 2006 coupe without the Bose system. I took the day off today and took some measurements for my own custom box. This is what I wanted to address:

1) Make box match the angle of the back of the trunk (73.7 +/- 1 degree)
2) Make it as wide as I can without having to have complex clipped corners. I made it 26" wide so it wouldnt interfere with the trunk lining on the roof when it starts to curve down.
3) Tall enough in the back section to go right up to trunk lining.
4) Extend height up again after I cleared the low level in the back.
5) Make sure the extended height did not conflict with the magnets on the Boston Acoustic 6 x9's (SL 95's)
6) Make sure the box didnt extend out too much so I could still pack two medium suitcases for a weekend getaway with the girlfriend (don't underestimate how important this is.

I attached two PDF's showing the box and it's dimensions. The drawing doesnt mention it, but the board thickness is 5/8. It will be constructed out of Baltic Birch as it is very strong and no more dense than MDF.

Cheers,

Marshall

 

Looks good. I'm working on the same thing for my sedan. Make sure and post pics when you get done. You going ported or sealed?

 

Sealed. I'm planning on putting in two 10" Boston Acoustic G2's. They have been described as being better sounding in a small sealed enclosure. Personally, I listen to rock and instrumental music....I want my bass response to be more punchy than sustained. I will be driving it with the Alpine 1 x 600 watt amp.

As for the box...I assembled it today after work. I did have a couple changes to assembly. I'll take pictures to demonstrate and most likely update the drawing as well.

Consider the fact that you have a sedan and I have a coupe, mine is a 2006 and I'm not sure what year your car is, and my 6 x 9's are a particular model. Knowing these variables...make sure your car will accomadate my drawing. In fact, if you have any adjustments from what I have in my drawings, I'll make revisions for your car if it helps. Just let me know. Ohhh....when it came time to mill the panels, I converted to Millimeters...it's a bit easier. With that said, I can reprint the drawings in metric.

Marshall

 

Thanks for the offer, but the sedan has slightly different dimensions. I drew mine up in Google Sketchup, I'm going to try to build it sometime this week. I'll post pics when i'm done.

Matt

 

What is the internal air space of the enclosure? I find it odd that it is the single most important number but you don't have it listed anywhere.

How does it sound?

 

I havent done the math yet because: 1) The design changed. 2) It's irregular shape lends itself to a more complex calcualation.

You're point is valid though...I'll come up with the number. In designing this box, I didn't use ideal volume as a guideline... With the space to work with being a premium, use of space as a guideline...not an audiophile's answer, but the truth. I still wanted to have some trunk left. With two 10's and 600 watts....I'm certain that I'm going to have all the bass I'll ever needs and most of my trunk.

I will say that there were prefabricated Boston Acoustic boxes (made for the G2) at the store that are awfull close to the size of my box. I couldn't use it because of height clearance. But for the volume lost in my reduced height, I gained back by efficient use of the matching angle in the back of the box...I suspect I'm close.

 

The general rule of thumb is to keep it within 10% of the manufacturers recomendation. It won't just be bass output that will change, it will be the entire range that the sub plays in that can change. I wouldn't waste the time designing a box until you know exactly how big it needs to be. Also, don't forget to account for the displacement of the subs when you do the volume calculations.

Just to illustrate my point, if you have a sub that requires a 1.25 cu/ft box and you are running two subs you'll need a 2.50 cu/ft box. 10% of that would leave you with a range from 2.25 - 2.75 - that's a pretty tight tolerence!

There's an old saying - the worst sub on the market in its ideal enclosure will outperform the best sub on the market in the wrong enclosure!

 

The box has an interior volume of 1.307 cubic feet. Spec calls for .5 cubic feet per speaker including basket displacement. This leaves a net .307 cubic foot of overage. I will line the interior of the box with some dampening material to tune the box to an even 1 cubic foot.

 

awesome, that sounds like a good plan. Make sure you post pictures when you have it installed.

You may also want to consider putting a small vertical support in the middle of the enclosure between the subs - it probably won't be required but you have some extra space inside and it definately won't hurt.

 

Will do... I'll be cutting out the holes tonight. With the box assembled, I'm kind of limited on what I can do to partition the two drivers... At best, I can put something in between simply to consume space.

I'm not sure what to use for dampening material...something more ridgid than not. I've been reading that soft materials such as fiberglass actually effect the box such that it has virtually more internal volume....not what I want in this case. I'm wondering if perhaps a light, yet ridgid foam is in order? I can cut these into managable bats and glued to the interior of the box. This gives me a control over volume. On the other hand, perhaps some expanding foam in the corners will be effective...but this gives me less control.....thoughts?

 

I went to home depot and bought a 2" thick slab of polystyrene that is quite ridgid. I will but it in managable peices and glue it to the back of the box with liquid nails. A 2" thick layer along the back of dimensions 2 x 9 x 24.75 will have a volume of .2578 cubic feet. I'm at 1.307....this should bring me to 1.04 Cubic Feet....4% over manufacturer spec. Hell....I could cut a little strip and glue it down the middle to make up for the 4%....yep, that's what I'm going to do.

 

Oops...It wasnt 1.307. It's 1.36 I have now. I need to fill in .36.

 

Here's a couple of shots. I'll be turning the car in for install tomorrow after work....should be complete in 48 hours.

 

Here's a couple pics of the final install.

 

Couple more.