Hey all, I hope you don't think I'm coming off as a know-it-all. I'm far from it and I'll be the first to admit that there is so much that I don't know and probably never will. That said, there are hundreds of correct ways to tackle any problem. There are also countless incorrect ways.
If you don't mind me sharing a little of my background, I used to be a member of the Image Dynamics Elite team back in the mid to late 90's on the IASCA, USAC and SLAP circuits. I learned the bulk of what I know from the guys that ultimately became the heart of the Image Dynamics engineering team until the breakup a few years ago. I don't compete anymore and haven't since early 2000s but I still enjoy SQ competition level sound. My installs have definitely shifted to more of the stealth side than the flashy side though and are definitely not as complex as they used to be.
Over the years, I've done sealed, ported, bandpass of various orders, isobaric, aperiodic mats, you name it I've probably built it at one point in my life. I find that sealed is my overall preferred method. Affords better mechanical control of the sub, slightly higher power handling, smaller enclosures, and just easier to build and integrate.
Spraying the interior of the enclosure with undercoating used to be pretty common. It doesn't technically absorb vibration, but it lowers the resonant frequency of the enclsoure by adding mass. It's the same principal behind sound deadening mat and spray. Add mass, lower resonant frequency below a point where it is an issue. The up side is that it can help seal minor leaks.
The polyfill is also a great trick for small enclosures. General rule is to start somewhere around 14-16oz of polyfill for every 1cu ft of enclosure space. You can sometimes "gain" anywhere from 25-40% of perceived air space which really means you're altering the internal airspace in such a way that the mechanical properties of the sub alter and perform as if they were in a larger enclosure. The larger the natural air space of the box though, the less effective this becomes.
A half way decent sub in the right enclosure can sound better than the best sub in a poorly designed enclosure. I've seen people thrown money at the best equipment on the market only to skimp on the install and end up pissed off because it underperforms.
Hopefully I can get back in the shop one night this week to finish up the front baffle. If not, I'll see if I can squeeze it in between doing the bilstein/FJ suspension swap this weekend.
