custom box

[lu]

I'm trying to fabricate the box design that is available at polk.com but with a few changes to fit my car perfectly. It's a 2.1 cubic ft single bandpass for the MM120. The modifications I have made to it place it's height at about 12.5" internal height. With the .75" of mdf on top there would be about a quarter inch of space between the bottom and the 13" vents... is this too little? I've been doing a bit of research on the matter and have found that sometimes people put the ports on the outside. Would this be a possibility? I'm planning on the front and back of the box being plexiglass and I'm wondering what size plexiglass would be safe to go with. I'm using 3/4" mdf on everything else. And finally I'm curious if the MM124 would work in this box the same as the MM120

[Kim]

Lu,
Since you are planning to use plexiglas for the front and rear panels, I would suggest not having the port protruding out of the enclosure. The "plan B' option would be to change the port length. If you use two 4 inch ports that are 10 inches in length then this will raise the tuning frequency by only 5 Hertz. There will be a slight increase in upper bass frequency output also. The original tuning frquency is 57 Hertz and the new tuning frequency will be 63 Hertz. I have attached response graphs below to show you the differences. Now keep in mind that these are "out of car" response graphs.


Happy Tuning!!
Kim