Hey GGM,GibsonGM wrote:Good suggestions guys, thanks! I'll try a pad. It has a weird resonance when I play 1st C...pretty good otherwise. I still have to stuff it with insulation or something, tho! {lazy}
I'm not exactly an expert, but have made a few custom cabs, so here's my 2 yen ...
1) I'm not clear about all the dimensions of your cab, but the slant probably reduced the interior volume of the cab (this is critical in a closed, unported cab). I know you said you made it deeper, but 12" bottom to 6" top is a pretty radical slant, so interior volume is probably down by 20% (just a guess). A while back I explored "optimum" enclosure size for a 12" 100dB speaker, and the ideal cab is the size of a closet! The thing with adding foam or felt "wadding" is to create an artificial volume by soaking up some of those interior waves. It also breaks up some of those specific "pitch assaults" o the backside of the speaker cone. Just throwing a small wool blanket on the floor of the cab might work wonders! (wool and felt seem to be better than cotton ... so I've heard)
2) The slant complicates how the waves move around in the interior. How exactly that works is apparently a very deep science ... at the same time, most folks say it still requires a lot of experimentation. In other words, even the scientists admit that the calculation to real-time achievement of great sound is somewhat hit-and-miss.
3) Porting is REALLY complicated, while open back is a lot more forgiving. But if you need that closed back "projection" and tightness, you have to work at it. As has been said, some speakers just don't work with open back, and some don't work closed. (very generally-speaking, low-efficiency speakers do well open, and more powerful and efficient speakers like closed environments)
I get you about lazy (welcome to the club!), so my suggestion is to just throw any towel inside and see what happens. If it seems to work, you have motivation to try other stuff. And as has been mentioned, irregular bunching (or waves or wadding) will definitely work better than just a flat piece of carpet felt. Don't stuff the cab too much, or it will muffle the tone.
Best of luck!