Acoustic treatment


I want to build my own bass traps and was wondering if there are any other alternatives to fiberglass and rokwool. Foam is not a consideration as I don't believe it has the necessary qualities for absorption. I have heard of cotton batting, does anyone have experience with this material. The idea of fiberglass makes me itch just thinking about it, but I'm resigned to using it or rokwool if that's all I have.  Please make suggestions and let me know your experiences.

Thanks
Mike
zardozmike
Tim, I think you should find a job as a used car salesman, excuse me salesperson.
Actually summed bass below 100 Hz is an advantage in most acoustic situations you would have in the typical home.
Jon, It would be easier with identical subs. But if you have to use the large sub midway between your speakers and the small ones flanking. I would mono the lot. 
Geoffkait  you did not answer the question, how big? Wikipedia has the equation. I'll give you a hint. It is highly unlikely that anyone here has a room large enough to fit a Tube Trap that large.
Back to Tim, The term "room control" is a misnomer. You are not controlling the room. You are controlling the speaker to correct response abnormalities of the speaker/room system, to make both sides have exactly the same response and correct timing so that the sound from each driver hits the listening position at exactly the same time. With a good unit the listening position can be any where in the room! Where ever you plant the microphone. You still have to minimize acoustic aberrations in the room or you will waste a lot of power and even bottom out a sub driver. Any sub woofer system is going to sound better because you can correct and improve the sub inherent frequency response which is hardly ever flat. Every uncorrected smaller (12" and less) sub that I have ever measured has a response curve that falls off as you go down. 
This can be correct and I even give them a response that rises to +3 db at 20 Hz then at 28 Hz falls off like a rock 10th order! Tim, if you want your bass to really perk up you want to make sure each one is exactly the same distance from your listening position. You can put them anywhere in the room as long as the distance is the same. They should preferably all be up against a wall. It also helps if your speakers are also that same distance assuming everything is phase correct. 
                                         
                            
Huh? OK, I’ll repeat it. Maybe it will sink in this time. The frequency of operation for a Helmholtz resonator is a function of 3 variables - volume, nozzle diameter and nozzle length. Therefore, you would be able, well, maybe not you personally, but someone who knew what he was doing, to construct a Helmholtz resonator for 20 Hz that did not (rpt not) have a very large volume. You can also affect bass performance with tiny little bowl resonators. There’s lots of ways to skin a cat.


Sorry folks. It falls off like a rock at 18 Hz. My typing is worse than awful.
They did not teach boys how to type because we did not become secretaries. 
Geoffkait. Still not a direct answer. I probably knew what a Helmholtz resonator was before you were born. In 1978 I had two RH Labs (Randy Hooker) sub woofers. They were essentially enclosed Helmholtz resonators adjusted to 30 Hz if I remember correctly. They were by today's standards huge. I do not have a scientific calculator but to make something the shape of a tube trap a 20 hz Helmholtz resonator it would have to be huge. Think of a 20 Hz organ pipe. 32 feet long. Yes I know it is a different principle. Oh, and the equation is

                          F = v/2 pi times the square root of A/V L

F is the frequency, v is the speed of sound, I hope you know what pi is,
A is the cross sectional area of the stem, V is the volume of the chamber and L is the length of the stem.