Introduction:

This is a step by step guide as to how I made my fibreglass door builds. They were built to house some 16.5cm JBL P6550e component speakers in a sealed enclosure to get the best mid range response. Make sure you read this through though before starting as it will give you a better idea of what kind of obstacles you’ll come up against. Also I’ve tried to write it as detailed as possible to give you the best idea, as I unfortunately, didn’t have a camera at the time I was making them. It really is quite easy so don’t let the length of article put you off having a go! If you do make some door builds, it will be a lot easier if you have the speakers you will be using, from the start to ensure the best fit.

this is what we're making

Think about what you're doing:

This might sound pretty obvious, but if you plan what you're going to be doing properly, it will save you having to make big alterations later on when they will be a lot more difficult to correct. If you are planning on building something similar to what I’ve made, think about how far the speaker will protrude from the door, and if you have enough room to still use the window winders if you have them. If window winders aren’t a problem then designing the layout for the builds will be a lot easier. Also using slightly smaller speakers will make it easier as the main problem I had was fitting the large speaker in around the winder.

my JBL component speakers

Make a template:

Once you’ve decided on where you want the speaker positioned and the basic layout of it all, you will have to make a rough template of the space available to you. I got a large piece of card (actually a folded out cereal box) and stuck it in place around the far end of the door card. I then marked out all the places I could not interfere with, e.g. Door handle and window winder, and also cut the card so that it would not get trapped by the door seals when the door was closed. Once you have a template of the space available, it is then a lot easier to position the speakers in the way you desire (if using components its recommended to try and keep the tweeter as close to the listener as possible due to the directional properties of treble). Remember though that the dash sticks out in front of the door card when the door is closed, so make sure you leave space for this.

Create the base plate:

Once you are happy with your cardboard template, it is now time to start building! The best material to use for the base plate is very thin MDF (rough on one side, smooth on the other) as otherwise the weight will quickly add up and probably wont do your door hinges much good! Trace around the template onto the MDF, and then flip the template over to make the base plate for the opposite door. When both plates are cut out, test them again in the car with the door closed and make any fine changes to each one to make for a good fit. You may want to slightly sand the edges of the plate so that they are angled towards the door, to make them appear to sit flush with the door card.

Make the speaker mounts:

Next up is to make the mounts for the individual speakers (and cross-over if using components). This is basically done by buying a sheet of MDF about 9mm thick, and cutting out rings all the same size as the speaker mounting ring. Layer these rings on top of each other and position the speaker in them, making sure that the rings are just enough to keep the speaker raised, for example: My speakers were about 68mm deep and by using 8 rings of 9mm MDF, I made a mount 72mm deep leaving, just 4mm clearance between the speaker and the bottom of the mount. This was to make sure the speaker didn’t get in the way of my feet while driving. Unlike sub woofers, space isn’t as important to mid-range drivers, so you can mount them in a very enclosed space without worrying about loss of sound quality, although bass frequencies will be reduced. Once you have cut out the right amount of rings for each speaker you will have to stick them all together. I found the best thing for this was to use a liberal amount of ‘no more nails’ on each ring and clamp them all together creating two small cylinders. Make sure you use a constant line of glue round the ring and when they are pressed together, any excess glue can be smoothed round the inside of the speaker mount to make a good sealed enclosure.

If you are mounting tweeters, obviously cutting lots of rings in such a small size would be a nightmare, so I found the best thing to do was to wrap some cardboard around the tweeter mounting rings that came with the tweeters, and sellotape the card in place, effectively making a smaller version of the mid-range mounting ring. Make sure you have made the ring quite thick so that it may be glued securely to the base plate later on.

Lastly you will probably need to make a small platform for the crossover to sit on (if you have one). This is best done using some more 9mm MDF. Make a card template of the crossover but leave about 1 inch around the edge that the cables connect to the crossover on. This is so that you can lay the cables through the pod before you fibreglass it all, when it will become extremely difficult to run cables through once set. Trace round the template on the 9mm MDF and cut it out and then use some small strips of MDF to rise the crossover mount enough to run the cables underneath it.

Now all your mounts are done, drill any necessary holes you may need for speaker cable or anything. Don’t make the holes too big or sealing them will be a problem. With the card tweeter ring, just trim a hole in the middle big enough for the cable, and with the mid-range ring, drill a hole in the side as any loose cables will be hidden by the fibreglass later on. With the crossover, try and drill the holes inline with the terminals as this will give a neater finish.

Finishing the base:

Once you have all your speaker mounts and your base plates done, it is time to position them together. Lay the base plates down flat and then place the mounts for each speaker (and crossover) on the base and draw round each one. Once again, make sure that none of the speakers or any part of the door build will interfere with the dash or with your feet when the door is closed. My pods stick out just a bit further then the door pocket, and I’ve had no problems with them, although much more then that may pose as a problem. When everything is checked and your sure that it is all fine and good, use some more ‘no more nails’ and stick each part in the place you require. Position each piece so that the holes you have drilled are facing the component platform, as this will make running the cables through easier. Use a couple of screws as well from the back of the pod to keep all the bits in place while it dries. When it is all dry and secure, thread the cables you will need through the holes making sure that the midrange cable comes through the right hole in the crossover platform so that it sits inline with the terminals it will be connected to and the same goes for the tweeter. With the supply cable coming from the amp or headunit, make sure you drill a hole in a suitable place so that you can connect the cables to the crossover easily. Make sure that the cables are longer then you need as if they’re too short, it will be very difficult to put longer ones in later on. Also don’t worry if the pod seems a bit flimsy on account of the weight of the mounting rings, as the fibreglass will stiffen it all up a lot.

Getting ready for the fibreglass:

Now comes the fun part. You will need a fair amount of fleecey fabric from your local fabric shop. Fleece is good because it is very stretchy and quite thick, so when it soaks up the fibreglass resin, it goes very hard. When buying the fabric, remember, the thicker and stretchier the better. Once you have enough fabric, you will need to stretch it over the base plate and mounting rings so that there is a smooth transition between the top of the mounting rings and the edge of the base plate. Start by placing the fabric on a flat surface and position the base plate face down on top of the fabric so that the mounting rings are touching the fabric and the back of the base plate is closest to you. Find the flattest edge on your base plate design, and begin by pulling the fabric evenly and fairly tightly against the flat edge and stapling it in place. When its smoothly stretched and stapled against the flat edge, pull it tight over the opposite side, making sure that there are no creases in the fleece and that it is of fairly even tightness. Continue pulling the fleece over the front of the door build and stapling it all around the back of the pod. If you pull certain bits slightly tighter you can adjust the definition of how the mounts appear and how smoothly everything ‘flows’ together. Make sure that everything is pulled tightly and evenly over the whole front of the build and that there are no creases. Also try to make the back side of the build as neat as possible as this will make the finished build sit better on top of the door card. When putting the fleece on, make some small holes where the component mount is and pull the cable through as when its covered in resin it will be a lot harder!

Fibre glassing:

There are various places on the internet that you can buy fibreglass resin from but it will probably be easier and maybe cheaper if you go to a boat yard or marine merchants as they have loads of the stuff. You will also need approximately 20ml of hardener to every 1kg of resin used. I’m not sure the exact measurements of each one but if you buy from a marine merchants, they should be able to help. When your completely happy with your builds, its time to start laying on the fibreglass. If you’ve not worked with fibreglass resin before, only mix up a fairly small amount so as not to waste it. I mixed my 1kg of resin with the 20ml of hardener I was given and within 5 minutes it had as good as set. This stuff goes off quickly so only mix up a small amount or enough to cover one build, or even better, get someone else to help you. When you’ve mixed it together, get an old paintbrush and basically start slapping all the resin onto the fleece till it soaks in. You will have to apply it fairly liberally so that it soaks in but you can easily tell when a section is soaked as it will go darker. It may help if you get a fairly light coloured fleece as well if you have the option. If you have time after covering the front, try and cover the fleece left over on the back as well, but you can always do this after the front has set. When you’ve finished doing the section your doing, leave the pod outside for about half an hour until it is dry (the fumes from the resin are unpleasant to say the least!) and then mix up some more resin and hardener and do any more that needs doing. When they’re both fully covered in resin leave them outside overnight to dry fully. You will then need to trim the holes out where the speakers will go, give the whole pod a light sanding and also to trim as much excess fleece from the back as of the pod as possible.

speaker and an empty door pod

Finishing:

Now that both pods are fully dry and fairly smooth, you can choose how you will cover it. I chose vinyl as I thought it would be easier then spraying, but as I made the shape of my pod fairly intricate, covering with vinyl was a nightmare! If your finished design is fairly smooth and flat, then vinyl will be fine. Fit the vinyl in a similar fashion to the fleece but when placing it over, cover both the pod and the vinyl in contact adhesive and leave for a few minutes until tacky and then press them firmly together and staple on the back. If the vinyl does come away after you’ve stapled it down, leave it for a few hours then press it down and it should stick no problem. If you choose to paint the pod, you will need to cover it in a thin layer of filler and then sand until smooth before spraying. Finally, you can now put your speakers in and wire them up.

speaker fitted into the pod

The conclusion:

I do recommend people to give it a go as it is fairly cheap and also fairly easy, if a little time consuming. The results however are worth it, and you will notice a big difference in sound quality.

speaker fitted into the pod

The Max Power/Haynes manual on ICE is also quite a good book concerning door builds. Good luck.