I have a new favorite holiday. Fiberglass Day! Though I wish it were a national holiday so that everyone could enjoy it, for now it will have to be my own personal holiday.
I can already hear you now, "What the hell are you talking about, Pete????"
I took yesterday off to work on my car. I've got a GREAT subwoofer for my car stereo, but it was designed with accoustic quality and durability in mind with little or no thought for how it looked or how heavy it was. I didn't really feel how heavy it was until I upgraded the suspension on the GTI. That made it so that I pretty much had to upgrade the sub enclosure.
The sub placement I've got now is perfect. I wanted to try and keep that if I could. The shape and size of the box really made the bass tight and powerful. It is the best of both worlds. If I'm listening to something that is technically challenging to reproduce in a car (classical, jazz or some electronic music), I have a program for that equalization so that I can enjoy the music. If I want to put on some Black Eyed Peas and assault the neighborhood with some booming bass, the sub will handle that too. As I said above, the problem is that the sub is ugly and heavy.
In an attempt to make a box with similar characteristics, I designed something that would work very well, but be challenging to form. Because of my needs and the desire for strength in certain specific areas, I decided that a hybrid fiberglass/MDF box would work best. I don't know too many people that build like this, so I was kind of going out on my own. MDF is great accoustically. It just stinks because it is heavy. Fiberglass is light, but isn't as accoustically perfect as MDF. I spent all day yesterday working on building a frame upon which to drape the fiberglass.
My other constraint is that I have very little money for this project. My goal was to build a sub enclosure with either stuff that I've already got, or things I could get cheaply. My budget for this entire project was $30. I had resin and hardener. I also had a pretty good amount of fiberglass cloth. I got 2 sheets of prepeg for $14 each. I needed hot glue sticks. I barely made the budget... though if you add in tax, I guess I blew it by a buck or two.
I'd found a place that sells prepeg fiberglass. This is fiberglass with the resin already impregnated into the cloth. The resin hasn't been activated yet, so the cloth is still flexible. This is used in places where you've got some difficult fabrication to do. Prepeg allows you to form things first, glue the fiberglass to the frame, then activate the resin and it gives you a base coat of fiberglass. You then can remove part or all of the framing and add additional fiberglass where you need more strength.
This plan worked well in some ways, not so well in others. I wasn't happy with how the prepeg fit on the form. It really didn't feel right and wasn't flexible enough to make the kinds of shapes I wanted. I figured I'd fill in with regular fiberglass when I got the shape I wanted. The other problem was that I ran out of time. I didn't realize how late it was and how cold it had gotten before I activated the resin on the prepeg. It was too cold and the resin didn't set up properly.
The end result is that I learned a lot and I'm going to start over. I tossed the prepeg idea. It wasn't designed for the kind of things I wanted to do with it. I also tossed the idea of starting with a technically perfect box. I'm going to basically smash the box I created and come up with something simpler and less accoustically perfect. It will be substantially lighter though. That is always important.
I'll post up when I get something worth looking at.
Pete
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