Thread: How to build speaker boxes

I don't do this as a hobby or a job so it is based on some audio engineering I did as an under graduate. Mid range and tweeters are no problem and as long as you can mount them somewhere so they are firm and don't vibrate you should be fine. For the bass speaker you want the biggest circumference you can get. The enclosure should have as much volume as you can afford in terms of space. The bass speaker needs to have the back side of the speaker isolated from the front i.e., you don't want the pressure wave come of the back of the cone coming around an intefering with the pressure wave that has come of the front of the cone. For efficiency and extended low end response you would use a vented enclosure but that is more difficult as you effectivelly have to build a tuned circuit balancing up the volume of the box and the length and area of the venting port.

Fill your enclosure with sound absorbing material so that it looks like an infinite volume and you will reduce the reflected waves coming of the surfaces of the enclusre and intefering with the back of the cone. Bass is fairly pervasive and can be placed without worrying about line of sight from the speaker to the listner unlike tweeters and to a great extent mid range where you should not have things in between you and the speakers.

If you want to make the most of the power from your stereo use a heavier cable particularly for your bass speaker, although you can get bass speakers with an amp built into the box to reduce the problem of lossess in the wire.

I suspect that all this is probably way beyond what most people want to do, unfortunatelly I don't have a speaker model I can recommend so perhaps the best advice is to go to a car stereo place and have the boom boom boys fit or recommend something for you.

There are plenty of tutorials on the web showing what is the preferred volume size of the base enclosures.
I made mine from MDF and filled the inside with the stuffing used for pillows. It's a polyestor type of cotton wool and works very well. It took a number of attempts to get the volume right but in the end I found that I had to stuff as much of the filling inside the box as I could.
Messing around with port sizes is time consuming and should really be left to the pro's...so just go a regular closed volume box and stuff it out.
I used cargo ratchet straps to secure mine down. It's in a Discovery but you get the idea.

No way I can have unobstructed line of sight (line of ear? ) for mid range rear ones - they will have to be in the corners kind of behind the seat backs.

Mind you - I'm not after afficianado quality sound... itl's a Defender after all....



Large diameter bass eh ? That's gonna be IMPOSSIBLE in a Defender twin cab.

additional to teh above - there is a small(ish) (well, shallow anyway) "tool box" under the rear seats. I wonder is there a type of speaker maybe I could put one or two of under the rear seats, facing forward. These use this toolbox as an enclosure - lined with MDF and stuffed appropriately ?

Speakers would need to be relatively small in diameter. Looking for some low range don't necessarily need BIG doof doof bass !

VT Jaycar at Aspley will have all the bits you need (except MDF)

You could replace the existing rear speakers with components. You'd be able to put the tweeters up high in the back and they wouldn't get bashed by peoples heads. If you're wanting to keep to a tight budget then have a hunt round second hand and see if anyone is flicking off any tweeters and crossovers, you could reuse your existing speakers.

If you're wanting low end then look for a spot you can fit a box that's about 0.7ft3 will take a 25cm diameter, 15cm depth speaker. That's about the space requirements you'd need for a 10" subwoofer.



This is an Image Dynamics IDQ10 v2 subwoofer in a 0.4ft3 enclsoure (those are size 12 shoes for reference). It worked very well to add some decent uumph in a car where boot space was at a premium.

.7ft3 ? You've never seen the inside of a Deefer twin cab have you. There's not that much room for that type of setup anywhere that I can see.

Dumb q: What's a "crossover" ?

Edit: OK from here http://ezinearticles.com/?Car-Audio-...Them?&id=74801 I now know what it does - but I have no idea what it looks like, how big one is, how many I need, but I assume passive are the way to go in a bsasic application like the one I am proposing.