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May Issue Tech Feature: Passenger Footwell Enclosures, Part 2

Mobile Electronics May Issue, May 10, 2016 -- In the previous article we discussed adding bass to an audio system and the challenges that go along with that. We zeroed in on the footwell enclosure, an often overlooked option for adding bass to a car with limited space. Now let’s look at construction of a footwell enclosure. We are going to look at a build from start to finish in a BMW 135i Convertible. As we discussed in the last article, convertibles can be excellent candidates for footwell enclosures. This car was a perfect example.

We had the client’s permission to cut the carpet in this car, so it was time to do a little reconnaissance. I took apart the necessary trim pieces so I could pull back the carpet in the footwell area. Typically, removing the passenger kick panel trim and a fastener or a clip or two will let you pull the carpet back. If the carpet is very difficult to pull back, and you know you have all of the fasteners removed, there is a possibility that it has a large piece of foam attached to the back of it. That was the case in this car. While it is more of a headache initially, the space the foam takes up ends up paying dividends in available airspace. Once the carpet is pulled back, make sure there is nothing in the area that would hinder you from using that location. I haven’t run across anything yet, but always look. You never know what you might find. At this point I usually decide how the carpet will need to be cut. In the case of one of the NSX enclosures, I was able to cut two lines in the carpet and have it lay flat. In the event that the enclosure was ever removed, the carpet could be repaired. I don’t think it would look perfect, but both cuts were in molded corner seams, so it wouldn’t be too bad. For this car I cut out a conservative area of carpet and foam. The foam ended up being even thicker than I initially thought!

Determining Factors

With the carpet addressed, it was time to bring the subwoofer in the car. Now I had a good idea of what I was dealing with. The main goal at this point is to determine how far out the enclosure will have to be molded to fit the subwoofer. Check with the client to see what their expectations are when it comes to subwoofer orientation. I had a client that wanted the baffle for the subwoofer to be completely perpendicular to the floor. I was not very excited about this, as angling the baffle gives the enclosure more of a factory look. We always have to keep in mind that it is the client’s car and not ours, and sometimes what they want isn’t what we would want! This BMW was really a best case scenario. The subwoofer fit almost completely in the cutout area. The enclosure only had to extend the footwell area about an inch and a quarter. Now that I had determined roughly how far out the subwoofer would have to be, it was time to get to work.

Read the rest of the story in the May issue of Mobile Electronics, HERE:

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