Foreward;

I wrote this guide over the period of a few weeks, updating every now and then when I had spare time. I’d like to take this note to say I’m not a professional car audio installer, nor am I any kind of qualified wood worker this is purely a hobby for me. I am also not overally talented, anybody can do a simple enclosure like this with a bit of patience and planning. I built this box for a friend, pretty much mate’s rates and was made for 2 x Pioneer 10” woofers for a Charade two door hatchback and it got pretty decent results even though it never really got very far audio wise.

Safety;

The tools used to make this love to, and will bite if you don’t use them correctly. Make sure you’re familiar with what you’re working with or you could easily lose a finger, suffer a serious cut or get crap in your eyes which is never fun. I would recommend as a minimum would be safety glasses and a dust mask for working with MDF which is a known carcinogenic material.

Planning the box



Okay the first step and most important thing when building an enclosure is to plan it.
First go and measure out your car. Things to look out for are, do the subs fit on these dimensions, is it over the window line (only really important if you’re considering dB Drag classes) Do my seats still fold up? Can I still fit stuff in my boot if need be, eg. shopping, tools etc. Also, is the spare tyre accessible or won’t I worry about it? And lastly, but sometimes overlooked, will the box actually be able to fit through my boot opening into the boot??

When measuring, use millimetres, because this Australia, not America. Get as large dimensions as you can, because once you get in your box building programme you’ll find just how little space you may have, it’s always a lot easier to make it smaller than use space that doesn’t exist.

Next is to plan out how the dimensions you’ve taken will be implemented into the enclosure. The program I most commonly use is Car Audio Australia Enclosure Calculator (Free Download). The main flaw with this program is that the dimensions are permanently fixed into imperial, not metric. It does have a distance converter but it’s a pain in the rectal region to use, in my opinion. If you want an easy way to convert is to use Google eg. (12 inch to millimetres) or you can also take into account 25.4mm = 1 inch if you don’t have access to a computer. Another alternative is WinISD (Free download).

Now I’m assuming that if you’re reading this, you know what you want from your enclosure and you won’t have to be modelling different variations because I won’t be going into that. Things to take into account though, are, how much power you have available, how well do you want it to play music, do you want it to go low? etc. etc.

Once you put in your first dimensions, as always you’ll probably realise you’ve made it waay to large, don’t panic, you’re lucky! It’s better to have more than not enough. Ensure you have enough space on the baffle for your woofers, enough space for ports and also take into account the depth the port needs to work effectively. Then you can start decreasing the volume until you’ve reached optimum volume. Now that you’ve calculated how you want your external dimensions, take a screenshot of your final measurements so you don’t forget them. To take a screenshot of your screen, press the ‘PrtScrn’ button on your keyboard and then paste it into Microsoft Paint.

Now you can get out either a piece of paper and a pencil, or your favourite drawing program and sketch out the box so you have something to work off. This is a good time to work out your cut list, taking into account material thickness when working out the dimensions; you might end up with three pairs of the same piece, eg. Each two share the same dimensions, but all six make up the box, this way, cutting pairs is easier to get dimensions the same, a lot of pieces will have common dimensions. Label your pieces A (Baffle), B (Left) etc. etc. so you know exactly what to get cut up. Write these pieces down in a table and leave space to tick them off once you’ve cut them.





Making the box

What I used:

It's handy to have everything you need before you even start the box so you can just get stuck in and work. As a rough guide, here's some of the stuff I used.
1 x sheet of 1400x1200 18mm MDF board ($29 at Bunnings)
45mm 8ga Chip Board Screws (Price depends on how many you buy)
28mm 8ga Chip Board Screws (As above)
160mm PVC Pipe (Go for a drive around near construction sites $FREE!!)
Fibreglass resin (If you shop around you can get it cheaply, if you don’t shop around you’ll get ripped off, don’t buy it from Bunnings buy it from a fibreglass store)
Router
Selleys Polyurethane Aquadhere ($20)
Assorted Router bits (Round over, straight cut, flush trim etc.)
Router Jig (Free, make it in 10 minutes with a bit of patience)
Jig Saw
Circular Saw
Drill
P&N Quickbit set
90° corner clamp (Under $20 at a hardware store)
Tape Measure
300mm engineer’s rule
Sharp Pencil

Now I’m not going to explain how to cut up a piece of wood, it’s self explanatory. If you can’t, for whatever reason, take it to your local cabinetmaker or Bunnings etc and get them to cut it for you. Just double check the dimensions before you leave their shop as sometimes they can screw them up and it sucks finding out when you’re back home and things are already glued.

Label each piece of wood so you can easily identify them and lay them neatly in your work space. You can see in the pic below I have the 3D drawing, the cutlist and also dimensions printed out so I can easily see what’s what and tick off what’s been done.



This is time to turn some bits of wood into a box! Select the pieces you want to work with and assemble them together to check fit and squareness. Do this on a nice clear, level bench so you can lay it perfectly flat. I use corner clamps which are available at most hardware stores for far less than $20, it’s a worthy investment if you’re building it yourself and don’t have six hands. Take the pieces out of the clamps.





Run a nice, thick bead of your favourite wood glue along both joints and spread with your fingers if you’re keen. I used this Polyurethane glue which I think is awesome, however it’s a little more expensive. It’s better to have more than enough than to have a weak join, excess will be cleaned later. Keep in mind the glue is what should hold your box together, not the screws.




Clamp the pieces together, squarely and tightly. Take the time to get it right, the glue sets slowly so you have time to work with the join to get it absolutely spot on. Grab your drill and put in the correct size drill bit to pre drill for your screws. The size of drill bit and screw will vary but it’s essential to get it correct or you’ll wreck the join. Here’s a shameless plug for a product you can buy cheaply for just over $30. P&N quick bit adapter kit for your drill, means you can easily swap between tek bit and drill bit without bothering with your chuck, especially handy if you have a corded drill without a quick release chuck.




Remembering more screws is generally NOT better, but correct screws in the correct spaces will be a far better join you can look at the length of the panel and decide where you need to put the screws. A distance of around 150mm of so between screws is fine, just make sure you’ve applied a liberal amount of glue. Do not put screws too close to the edges of the wood or it will ‘bust out’, split or possibly ‘dog ear’ the wood which will weaken the join and look plain bad. This is especially important near corners of the box, do not place the screws in the very corner or you’re guaranteed a split, keep the screws at least 25mm away from any corner. Pre drill the screw holes, your packet of screws will tell you the corresponding drill size in relation to your gauge and length of screw. Put in your appropriate sized tek bit, (usually PH#2) and screw the screws in, if you’ve done it right, the screws will bite in nicely and screw all the way down and sink their heads themselves. If they go in put do not tighten up at all and don’t sink, the pre drilled hole is waay too big, if you split the wood or hear bad tearing sounds from your MDF you haven’t drilled the hole big enough. Once you’ve done this panel, continue to place the rest of the panels together, but do not attach the baffle yet because we’re not done with it.

You’ll notice this isn’t a plain baffle, it’s four separate pieces each with a different hole in it. First I dry assembled them together with minimal screws to make sure it all lines up. I didn’t attach it to the box because that’s un necessary at this stage. Each side were then marked with an X, from corner to corner to pinpoint the exact middle of the box, this will make sure they are both evenly placed and that the holes I cut won’t foul on the sides of the box or anything like that. As you can see, the top and bottom halves are screwed together, and this will be their final position so in this next step it is critical these pieces stay in these places.






Drill a small pilot hole through both layers, this will be the centre point for the router jig and you now know the jig will start at the exact same centre point on both layers which means perfect holes! After you’ve drilled these pilot holes, you can pull the baffles apart again ready to cut the holes. You can also see my router circle jig, it’s nothing special, in fact if looks quite terrible but it’s strong and reliable and the best bit, free! Screw the jig down on the prior drilled pilot hole and begin to cut the holes. Don’t rush this or you could really injure yourself. For this cut I used a small straight cut bit. No need to cut through it all at once, take a couple of runs on it, you’ll put a lot less stress on your router bit, if necessary, flip the piece over and go from both sides to get the depth you need. Cut the other holes out the same way making sure not to rush. You’ll see the second layer’s holes are slightly bigger than the woofers, this gives them a nice flush mount with the added strength of double layered wood.

Dry assemble these pieces again and check the holes are nice and round and overlay each other nicely. Test fit the woofers and make sure it’s how you like it. If you like, use your round over bit in your router and take the edges off the wood to make it look neater and reduce the risk of chipping.








Cut out the panel for where your port will fit, I used a jigsaw and a lot of patience. Make sure you’ve got enough room for the port face to bolt onto if you’re making it removable. You can glue the baffles together now, one piece at a time, first the bottom layer to the box, just like the other sides, then the second layer onto the first layer itself. Use plenty of glue on the second layer and spread it out with a paddle or something similar to ensure no air bubbles inside. On the second layer, this is an instance where you can use as many screws as you want to get it to clamp nice and evenly, go nuts! Just make sure the screws aren’t too long and protrude into the inside of the enclosure. Array the screws evenly for a tidy look, you can fill these later if you want. I also rounded over the top edges of the box with the router to stop them being chipped whilst it’s in the boot.




The next step was to make the enclosure air tight and smooth inside. Remember, MDF is porous and leaky boxes don't work well... Mix up a batch of fibreglass resin (Don’t do it too hot or it will crack like mine did, never, ever rush! ) Pour it into your box and slosh it around inside, lay the box on its side and let the resin flatten out, leave it until it dries then mix up a new batch and repeat for the other sides. You can also pour it into the corners to help airflow and brace the enclosure if you like. As previously said, go nuts!!





The port is very simple, make it as per your enclosure’s specs. This one is large, and also flared for maximum airflow. For a tutorial on flaring ports, check out Blackice’s PVC flaring tutorial, it’s a very easy process! This port is also removable to swap between daily and SPL (Low and high tuning). This is done by insert threads on he baffle face and M6 metric fasteners holding the port in, that part was pretty self explanatory, drill the hole, screw the threads into the wood with a hex wrench and now you have a solid mounting base for big bolts into your wood. The two faces of the top (The port and the baffle) aren’t exactly air tight so I also used closed cell foam around the edge of the box and cut out gaps for the bolts to go through, no leaks!






This is as far as this enclosure ever got in my hands and concludes this guide for a sub enclosure.

Good write up

you have done a good job on the write up mate, keep up the good work.

Catch

Great write up there. Well done, should help quite a few people out.

Awesome right up matey has helped me out a lot... fairly self explanitory but the bibreglass inside and that was good.. didnt thiunk any one other then me ever though of that

Nice one charger them subs go alright for the price hey

Great write up Charger, good tips and pics on the FG resin and how to make the removeable/changeable port.

EDIT: another benefit of the front baffle design is it allows you to use rails like the ones in my avatar as a grill, no bolts or crews etc showing for a nice clean look.

great write up charger, but this thread is missing one thing...a DIY on a spare tyre well box! i have a spare tyre well just sitting in the back of my car if you need one