The choice of your new sub and the output you get from it is going to be dependent on one primary thing, the choice of the box you put it into. While I will not dive into the types of boxes available I will dive into proper construction as this is where it all starts. Stevdart has provided a great sticky about WinISD for anyone building their own enclosure. Good bass response is all about the box. You can take the best sub on the market, put it into a poorly built box and get crappy results from it. Conversly, you can take the bling bling sub of the month and put it into a proper box and be amazed by the results. A proper box is also going to be about experimenting, do not be surprised to build "the box" and not get the results that you want. Sometimes 2 ,3 or even 4 boxes are built before you get the results that you want. A simple change in the net volume of the box, a change from sealed to ported, displacement and tuning frequency of a port can all make a drastic world of difference to how you prefer the tonal response of the sub in your vehicle. It is important to realize that on a forum populated by the younger generation, it is easy to get caught up in hype. One thing that the younger generation may lack is experience, not that all of the younger people lack experience, but most do. What may work for them in their application is certainly going to be different that your application. Do not progress on your application based on someone elses approach unless the results are going to be highly predictable. If you are prepared to pay good $ for a sub that you just have to have, expect also that your box is going to command a good $ to have it properly built. Most shops will not take the extra steps in box construction, so if you are having one built for you, ensure that it is what you want and not what they think it should be. Be prepared to pay the extra $ associated to it at the same time, no one works for free. A proper sub box should have the following.

(1) If it is a sealed box.

It is sealed, no air leaks whatsoever. A terminal cup is a prime point where a box bleeds air. Silicone the inside seam of the terminal cup and the inner seams of the box. In some cases it is a good idea to resin the inside of the box, fibreglass the inside seams of the box or just use some rubberized undercoating as well. Any box of any type needs to have all the little things looked after inside of it.

(2) If it is a ported box.

No air leaks in the box (like the sealed enclosure) and the port must be the right displacement and length for the sub chosen and the volume of the enclosure. I would follow the same principles building this box as I would the sealed box as pointed out above.

(3) It must be mounted properly.

A improperly mounted enclosure will bleed off energy by causing the box to rattle around your vehicle. This is energy being stolen from the box that you should be hearing in the form of sound. A properly secured box is not one that just uses backstraps or wire to hold it down, it is secured using aluminum, steel, bolts etc. to secure it firmly to the chassis of the vehicle to prevent it from moving at all. This will cause the energy transfer of the subs to come out of the box as sound instead of a box that wants to do the two step. A improperly secured sub box is also a missile in an accident. Sometimes even the smallest of accidents will send a 150 pound box flying through the air, at that speed and weight, it will cause serious and sometimes fatal blows if it makes contact with a person. It is called a accident for a reason. Secure the box properly, yes it takes time and time = $ when you are paying to have it done. Realize though that if you are paying to have it done, you get what you pay for. It also of course makes it much harder to steal a box when one cannot just reach in and rip out the drywall screws holding down the backstraps attached to the box and the cardboard cover over the spare tire. A improperly or unsecured box may also not be covered by insurance in the event of a theft.

(4) Proper construction methods and materials.

The use of proper materials can also make or break a box. K3 or particle board while it is cheap is usually best left for kitchen cabinets etc. The car envirmonment is hostile. It has a high trapped moisture content and goes through temperature extremes that will cause a improperly built and sometimes even a properly built box to fail. Particle board in general is a sponge, it sucks up moisture something fierce. This makes for a very weak box. All installers have a different approach on how they build their boxes. A good installer will learn new techiniques and apply them to their everyday construction methods.

As most boxes are built out of mdf, lets look a little further at them. MDF, medium density fibreboard, is more glues than wood. It is actually more or less wood dust that is glued and pressed together to create a sheet. It is a highly toxic substance that you should take great care so that you do not inhale the dust. Always use a respirator or at least a mask when you are working with mdf. It is best cut on a tablesaw or router. A jigsaw or skilsaw while they can be used, it is hard to get a accurate cut and maintain that all important seal on the seams of the box. MDF is also easy to split in half. Meaning if one wants to put a screw into a edge of it, the piece will separate and any strength in the material will be lost and you will be cutting a new piece. For this reason, if you are going to be screwing a box together, a pilot hole must be drilled first. Do not overtighten the screws as mdf strips very easy. If you are screwing the box together, ensure that you also countersink the heads into the box as well. This makes it far easier to fill the holes and then upholster the box later on. If you are not 100% familiar with your power drill, use a screwdriver to torque the final rotations of the screw so that you can feel it tighten. If you have a drill with a clutch on it, set the clutch so that it will not overtighten the screw.

Use a good amount of proper carpenters glue. Any and all seams where mdf is joined needs to be glued. There is no use in having glue overflowing and coming down the sides of the box, all one needs is a small but complete layer on the seam. Smooth it out with your finger and ensure that all areas on the edge are covered. A buildup of glue will cause the seam to actually bulge and not give a proper seal or bond. A improper bond or seal means that the air pressure inside of the box will cause that seam to fail. Glue is extremely strong. In 95% of my boxes, I do not use screws as they are unnecessary. I will use a Brad air nailer and use a length of nail at least double or more of the material that I am nailing though. Meaning, if I am nailing through a 3/4" mdf top panel into the side of a box, I will use a nail 1.5" in length or greater. The only reason the nails are there is to maintain the integrity of the box while the glue is drying. It is important to stay away from the ends of a piece of mdf as that is where it splits the easiest. I generally stay about 1.5" - 2" from the ends of a piece of mdf if I am screwing it together. I can get up to 3/4" away if I am using a 16 gauge Brad nailer and angle my nail away from the ends of the piece.

If you have large surfaces, these surfaces are going to flex. A flexing box is going to bleed energy from your all important bass response. A simple divider will solve this problem by being secured to the large surfaces. A divider is used to separate chambers in a box or if you want, the chambers may be coupled together by drilling holes into it. This will not weaken the enclosure provided you leave enough material to remain strong. Do not drill out a divider unless your box design calls for it and you have allocated the space occupied by the divider(s) into the overall box volume. Another way to keep a box from flexing is to use ready rod and run it through the box from one side to the other. Use a large flat washer and then tighten down a nut onto it from each side, this will squeeze the box together. Ensure to either use a lock washer or nylok nut so that it does not loosen off as the subs pound away.

If you have big monster acoustic hairdryers for subs and plan on putting them into a 1/2" mdf box, well, that is not the best idea. Yes it may save you a couple of extra $ but you will end up building the same box again properly. Use the right size materials for the task at hand. I will use 1/2" mdf only when faced with either a super small box or a highly limited space to work with. After that I will go into 3/4" or 1" mdf for my boxes. The bigger the sub with the more power behind it means that even more attention needs to be made to the box design. The inner stroke of a sub is pressurizing the interal airspace of the box. A weak box is going to blow a seam or flex. You must keep this from happening if you want all the performance that your new sub is capable of delivering.

When you are using a large sub that is also heavy, one needs to pay attention to how it is mounted. Drywall screws for the most part are really weak. I do not like using them except for screwing a box together. I do not use them for mounting subs if I can help it. A large heavy sub, powered properly and mounted to 3/4" mdf is going to want to move and rip out of the box. In this case I will double the baffle board on the box. The baffle board it the part of the box that the sub mounts to. If you can get 1.5" of baffle board to mount the subs to, it is going to be that much harder for the sub to rip out of the mount. I have seen numberous subs rip out of the mounting holes of boxes, even prefab boxes. A bolt with a T-nut is also a great way to mount your new subs as the T-nut is being pulled towards the head of the bolt with the mdf and sub sandwiched inbetween. The type of mount you choose is going to depend on the sub that you have.

When I build my sub boxes, I build them all the same way. There are some exceptions, like a fibreglass spare tire well enclosure but for mdf, they are built the same way. All of my past installers also now build their boxes the same way. I build my boxes as a sandwich. This means that it is the easiest way to construct a box from top to bottom. All cuts can be made at the same time for width, then cut as needed for length. I will cut my top and bottom first, then I will cut all the inner pieces, the front, back, sides and dividers (if necessary) to width. Then I will cut the inner pieces to length. This way there is little changing of the fence on the tablesaw and one piece is not 1/16" shorter than the other side may be.

Plywood may be used in a box design but use a quality plywood if you do. Birch, Marine Grade plywood, Oak and others all can make a exceptional sub box. It is all about how you put it together. Fibreglass will also bond to mdf and plywood and while it is a different topic altogether it allows you to accomplish things that mdf just would take a artist to create. If you are using fibreglass and want to bond it to the mdf, make sure that the area that the fibreglass bonds to has been thoroughly roughed up. It makes a far stronger bond again where two different materials are joining.

So build your box properly, do it right the first time. Take your time to lay out the design and consider the alternatives. This site has a great box volume calulator on it that I encourage you to use. Couple this with Stevdart's great post on WinISD and you are well on the way to great bass response. Remember to boom responsibly, no one likes a annoyance, you will also never ever recover your damaged hearing. For any changes, additions, deletions to the topic, please send me a PM and the changes will be made when necessary or as time allows.



I will also ask Stevdart if I can copy and paste his info here on WinIsd for you member to use as well.

Moderator please sticky this thread.

Great info there Rob

I know it's long people, but read it!!!!

hey, i tried to read all of that, sorry if i missed this bit but, what do u recommened is the easiest and best way to secure the actual sub box to your boot? my friend mentioned velcro?

You'd be surprised just how popular velcro is as an option.

When used in the correct amounts (generally, a lot), and placed correctly, it works very well. For example, putting several strips in different directions (that is, the hooks in different directions) will help prevent movement.

Otherwise, an L shaped bracket also works well. Simply put the box in the spot you want, push the bracket under, mark its location, take out box, screw down bracket. I myself use this method with two brackets as one side of the box is wedged to the side of the boot. It doesn't move an inch, yet can be fairly easily removed with some pushing. Provided that will only work if you have a solid floor you can drill into (ie. MDF).

Remember though, if using velcro, make sure the boot carpet isn't going to move

ROCK ON
R~R

hehe yeh thats wat i was thinking. thanks

What, no velcro is not alright. The first person that says it is gets an e-smack upside the head. A sub box is a missile in the event of a accident. No amount of velcro is going to keep it in place. While it may aid in keeping it planted in normal use, in a real world it is far from adequate. If the sub is making energy in the form of sound, the object that is coupled to it, the box, is going to want to go in another direction. Couple the motion of a moving vehicle and the box is going to move. If thebox moves, you are losing energy that should be coming out of the box in the form of sound. Velco to mount a sub box, um no and no professional installer should ever recommend it.

No offence Rookie, but just because it is a common option does not make it right. One accident with a sub box mounted improperly that comes directly and 100% back to your improper install will change your mind forever. Why on earth would you set yourself up for something like that is beyond me.

bolted down is the best method. in the case of a boot I'll use ROC straps but a hatch will see it anchored.

How does the sub box get out of ur boot in an acident? Thought back seats were stronger then that.

I believe making a floor out of mdf and than bolting it down is the key to success done it in all of my cars. at the same time velcro wouldnt hold crap, velcro doesnt even hold my neon up under my dash.

if you build a 12mm mdf false floor that fits firm to every edge of the boot then you can just screw the box amps and anything else you want to it and nothing will move all you have to do then is carpet or vinyl it and it will look like your standard boot floor then all is mounted and wont movethats how i did mine anyway

You havent even gone into differnet types of woofers, and as for calling them 'subs' i have to disagreee as i rarely come accros a woofer for a car that comes close to having the ratings and specifications that would classify it as a Sub-Woofer, creating the perfect box for a woofer is not as simple as you have described, it is a series of mathmatical equasions and you ahev to take into account if using a ported enclosior the angles inside the box or exclosure and how that is going to affect the way the sound is reverberated. using ported or sealed boxes using an acoustic sound deadener sutch as inabond can help with the cancelation of sound from the angles within the box. port possitioning is also a factor not only length and diameter or port (equating to volume of the port) again some woofers are designed to drive the air directly (designed for sealed enclosures, some to displace the air through a horn (reflex horn's and bandpaa enclosures) if you port a box for a woofer that is designed to drive the air directly you can ruin the sound and usual cancel out your lower end bass as the sound waves cross each other.



as for mounting your woofer enclosure it will depend on what type of enclusure you have and the type of car.

if you drive a hatchback it is most efective to use the hatch like a reflec horn compressing the air at the back which gives it more force as it gradualy expands, working jstu like a horn, youve all seen megaphones with there tinny little driver, without the cone they are useless drivers and put out verry little sound, this is a verry similar principle.



hope that may have helped somone

^^^ no it didnt help, this is a car forum, not a Home HiFi forum.