Hi guys! Just wondering if someone could help me out with sub enclosure design. First off, I have a Datsun 260Z 2+2. Ive whipped up some quick sketches in good ol MS Paint to explain my situation for those who dont know what Im talking about!

brown section is the rear 2 seats
purple is the fold down rear seat back
yellow is the rear wheel wells, strut towers and rear seat support sections
the smaller light blue section is a flat top section for the sub enclosure
the larger deep blue section with the two red things in it is the main face of the sub enclosure
two red things are subs
two green dots is just an indicator that between these dots its approximately 24 inches, so its gonna be a tight squeeze for 2 12s!






My car has an open rear space instead of a boot. There are rear seats that fold down to create additional rear cargo space. This gives loads of additional space however, I want to keep the ability to have these seats up for unexpected passengers.When the seats are up, there leaves very little room for luggage (read: car audio!) especially with the rear hatch door slanting down quite low.

There are 2 main requirements. The enclosure has to be shallow so that there is maximum floor space. The enclosure also has to be low in height as I plan to design some sort of retracting cover from the rear strut tower section to the tailgate, as there is no existing cover for this area and we dont want exposed subs and amps now do we?

The cover will be made of a thickish material so that you cant see through it in bright sunlight. Will this make mcuh of a difference, as although I want my subs in an enclosure, most enclosures are in an enclosed boot.

To make the enclosure clear the strut tower height, i was thinking of having the main surface angled as much as possible without having to resort to upward firing subs. Or would that be a beter idea if space is a major concern?

The diagram isnt to scale if that wasnt obvious. The gap between the strut sections is 24 inches and the car inside is 48 inches wide. I havent taken height measurements of the strut tower section, but im pretty sure its under 12 inches. maybe even under 10. So that may be a very important factor. A little revision on some pythagoras should help calculate roughly the height/angle/depth im going to have. But i also need to consider the depth of the sub magnet/basket etc so it doesnt foul the floor. And no, Im not sure of what subs I want yet. SQ on a tight budget is all I know. Maybe I'll even go 2 10s especially given the height restrictions i face. I could always put the cover up higher on blocks or something though.

Those are my main thoughts on the enclosure. Now the main questions I had were that with a sub design, does it matter what shape or size it is, as long as you have decent volume? becuase I want a very shallow enclosure that is very wide to make up for this lack of depth. Will the dimensions make a difference to the overall sound? Mainly with quality? SPL doesnt really bother me. I'd have this as a sealed enclosure. What i thought was that cause the volume is the same, the amount of air to move is the same as in a normal enclosure? Is this right?

Whats everyones opinions? are there any other suggestions? would you guys reccomend i have two seperate enclosures located to the left and right of the rear area, firing inwards instead? what about free air subs in this kind of application?

also, finally how would a single 12 inch sub performing if i mounted it on one side of the cabin firing sideways? would this effect the overall sound reproduction in a large way? does it muddle up the sound staging because of its location? I was thinking of customising the rear seat so that I only half of the seat folded up. the other half being totally removed for spacve for a 12 and amps. what you reckon?

Thanks guys for all your replies in advance. I know this is a long message, btu hte clearer everythign is, the better the answer (im assuming!) ask half a question, you only get half an answer!

If its gonna make it HEAPS easier, i'd strongly consider a single 12 or 2 10s.

On the other hand, take lots of measurements, do lots of drawings and see if u can pull it off. Me and a mate managed to make a sub box for a 10 to fit between the two front seats in a Ford Courier. It even had drink holders!!! If there is physically the space, you'll be able to fit it in somehow, just takes a bit of work!

But the face of the box where the subs are mounted won't be between thos 24" space will they?

Its only the top of the box that will be? therefore really you have plenty of room?

well yea theres technically plenty of room.. but i still want to use the rear area to put luggage for when i go away or groceries etc as this is my only car. This cargo area isnt very deep when the rear seats are up, so I wish to minimise the amount of room taken up by the sub enclosure.

any suggestions anyone? or just one 12 sidefiring? how does this effect the sound?

My best advice is to start with the usable enclosure volume and work backwards from there, as from here you'll find choosing a suitable woofer much easier. You seem like a calculating kind of chap, so this should be a bit of fun for you.

Work out the maximum space you have exactly, then draw this to scale on computer or paper. From here you'll be able to finalise things like total internal volume (based on wall thickness), surface area of the plane into which the woofer/s fit, and how much angle is placed on the main face to determine how much room is insde the box for a frame and magnet structure.

Since SQ is your goal - not SPL - and given that in a tiny cabin like the Z you'll get tons of bass even from one ten anyway, I'd highly recommend sticking with a simple single woofer in a sealed enclosures - with the option of porting if need be.

To give you plenty of options when purchasing I'd aim for a target volume of 1.5 cu/ft as a minimum - which is ample for a sealed or ported 10-inch, or ample for a sealed 12-inch. Most woofers on the market will work at thie optimum with this much volume.

Any greater volume you can achieve will be a bonus, but don't sacrifice enclosure volume (per woofer) for the sake of adding more woofers to the system. One woofer in a large box always sounds better than two of the same in small boxes.