Do you buy tweeters and swap out tweeters regularly? Do you want a way to be able to easily mount tweeters on-axis and make them look nice? Do you want to mount tweeters up on your A-pillars to avoid as many diffracting surfaces as possible?
If you answered yes to any one of these questions, I have just the solution for you!! My friend Glenn (GLN305), has come up with a very inexpensive solution for tweeter mounting that allows for easy swapping out of tweeters, makes it easy to mount tweeters on-axis, provides a certain degree of adjustability, and makes the mounting look nice. Glenn was kind enough to install a pair of Scanspeak Illuminator 2004-6020 tweeters in the A-pillars of my Mazdaspeed 3 and so I took pictures so that I could share his very innovative design with others on the forum.
Parts:
(1) 2 x PVC end caps (find ones that fit your tweeters, the ones in the picture are 1.5" diameter; some tweeters may need bigger end caps),
(2) threaded pipes (in Home Depot these are called steel nipples. Yes, the jokes about nuts and nipples are endless) these are threaded and used in lamps to thread the power cord through),
(3) hex nuts, a
(4) a can of bed liner to create texture, and
(5) optionally, a can of spray paint in a color that matches your car.
Next, sand down any imperfections on the end caps. Then drill a hole at the desired mounting angle where the base and the sides of the end cap meet. These have an approximate 45 degree angle for on-axis mounting.
Spray the end caps with two coats of bedliner. In this picture, Glenn stuck screwdrivers into the holes and then put a wire tie on either side to prevent the end cap from sliding off the end cap so that he could spray paint the end caps and then leave them out to dry. The bedliner provides texture to the end cap. After the bedliner, optionally, spray the caps with a color suited for your car. For example, you can use a can of touch-up paint to match the paint to your car's exterior paint.
Thread a threaded pipe into the drilled holes. They look like little ack ack guns. They appear grey in this picture due to the flash but they are in fact black, as you can see in other pictures. Use a grinder or pipe cutter to cut the length of the threaded pipes to slightly more than the thickness of your A-pillars.
Remove the A-pillars in your car, drill a hole in the A-pillars, and then fasten the tweeter pods to the A-pillars by pushing the threaded pipe through the A-pillar and tightening a hex nut on to the threaded pipe. Thread your speaker cable through the threaded pipe and connect to your tweeter. The picture shows that Glenn soldered and put heat shrink around it but you can also use quick connectors.
Note that the tweeters can be swiveled if you don't over-tighten the hex nuts.
Total cost was under $20 for both. Total time spent was less than 3 hours. We did it over 2 evenings because it was humid here in Austin and we had to wait for the bed liner to dry.