In my beetle I have two speakers on the rear parcel shelf cover, which works well. Only when you’re in the car with 4 people, the people in the back are getting deaf, OR you do not hear anything in front.
The solution to this is, of course, more speakers! The idea is to place speakers in front so that everyone hears the same volume.
The speakers at the back are now 16 years old, but these Kenwood speakers still do fine and give a good sound. So I bought Kenwood speakers again with about the same strength.
I finally bought the Kenwood KFC-E1365 speakers, these are 13 cm in diameter ( 11.2 cm mounting hole).
In the front, however, you do not have much space to place the speaker. You can choose between: speakers with their own housings, in the front firewall or in the kickpanels on either side.
The last option seemed the best to me, because speakers with their own housings will get in the way, and there is very little room in the front firewall.
There are ready-made panels available for this purpose, but they are not suitable for the 1303 (super) beetle.
I still had a piece of 3mm thick plastic sheet (polystyrene) lying around in my garage, so I decided to make them out of this plastic.
I started with a CAD (Cardboard Aided Designed 🙂 ) prototype:
You can not use a flat sheet because there is too little space behind the sheet to place the speaker.
These Kenwood speakers require a depth of 4.35 cm, which is already not so much, but that’s even too much for the limited space.
Therefore, I added a 3 cm elevation or “bulge” to create room for the speaker.
With the CAD prototype, I cut the piece of plastic to size:
After that, i made a frame to hold the plastic, and a shape for the speaker “bulge”. The idea is to heat the sheet to make it soft, and then push the shape into it.
The sheet must be held tight by the frame so that it does not pull the sides out.
The frame+sheet then goes above a cheap barbecue to heat it up and make it soft:
The sheet had to be heated evenly, but the barbecue is the hottest in the middle. As a result, I had to move the frame slightly to the left and right to get the whole sheet uniformly warm.
By poking it with a stick I could check if it was already hot enough everywhere. It does not have to be super soft, but a bit elastic everywhere.
Then I pressed the shape for the speakers into the plastic.
And it worked! :
At the top of the panel I left a bit more material then needed. That’s because the shape would pull material from the top. Now I had to trim that part off. And I also drilled holes for the speakers and cut a big round hole in it to fit the speaker.
Then I could check if it fits:
And it was fine! The panel is on purpose a bit too small on the side of the door, because then you will not see the edge of the plastic from the side once the carpet is glued on, and this way I didn’t have to bend that side of the panel.
I glued the carpet to the panel with contact cement, but first I put the carpets in the sun to warm them up. When the carpet is warm it’s much more flexible and ti can follow the speaker bulge better.
When the glue was dry I cut out the opening for the speaker and put some adhesive velcrow on the backside to mount it to the car. Because it’s velcrow I can always remove the panel if needed:
Then I used the carboard prototype to create a mirror image of the left panel, and then it was done:
It sounds and looks good, I am pretty happy with the result! 😎
And now everybody in the car hears the same volume.
edit 2017-05-13: For those who want to recreate these panels, here are the measurements from the template and the shape:
Start with a square piece of carboard of 2,5 + 1,6 + 5,4 + 24 + 1,4 = 34,9 cm wide and 34,8 cm heigh. Then use the rest of the measurements to recreate the template.
And this is the speaker shape: