Di ko pa mahanap ung spreadsheet for determining room modes. I recall that was actually in a magazine that I read a long time ago. Hanapin ko pa.
In the meantime, the best that I could get was this link:
http://www.componentacoustics.com/It includes a simple calculator for determining good room dimensions, but given a set of dimensions, it doesn't tell you which frequencies will give you trouble.
If you have a problematic room, you may be able to reduce those problems through the use of bass traps and portable diffusers, as well as the proper location of furniture. I guess the big problem is to know what are the problem frequencies and for that, you need a Real-Time Analyzer or RTA. That will provide you a graph showing the relative db in your room at each frequency.
After you have done all you can with acoustic treatment, then you can use a room equalization system such as Audyssey. My guess is that Audyssey is much better than most other systems in the market today. This is based on what I have read, as well as my own experience. In fact, if you don't have an RTA, you can get a good idea of the problem frequencies in your room by running Audyssey and checking out the equalization curve (available with Denon AVR's). The frequencies where Audyssey applies big cuts or boosts are the problem frequencies.
Audyssey does equalization for all frequencies, including bass, but probably the best specialized equalizer for bass is the Velodyne SMS-1 (subwoofer management system). This has a calibrated mic and built-in RTA which can show you in real time what happens to your sound as you adjust the equalizer, phase, crossovers, etc.
