I'd get an F. Alton Everest book first, "Sound Studio Construction on a Budget" or "Master Handbook of Acoustics, 4th Edition", and read about perforated panel absorbers in particular. A DIY one is cheap and easy and they work. Jon Risch's site is good on an ASC-style Tube Trap, but it's a heavy duty DIY project compared with panel absorbers. I thought my bass was fine, then clearly improved it with a panel absorber. Everest's books will also tell you how to analyse your room's resonant modes, which should tell you how to tune a bass-absorbing device to best effect.
Room Treatment Options?...What to use?
I am having some trouble with boomy base. No, it's not the speaker placement. I have consulted the Cardas sight and have the Robert Harley book, so I think I am ok there. But the base still seems boomy. I need a bigger and more silent room but don't have the $250K down payment money in the Silicon Valley. I can only spend a couple of hundred dollars. How can I get my hands on some effective room treatment/sound absorption material?...Are there places I can buy this stuff and assemble it myself?..Your help will be appreciated