I have the EP-500 and the SMS-1. It allows adjustments in every conceivable parameter, including low pass, high pass, slopes, phase, EQ level, frequency, Q, and so on. You can do self-EQ (listens to subwoofer alone), auto-EQ (listens to subwoofer along with your mains), or manual EQ. I thought the self or auto-EQ were not that great. Manual EQ is painstaking as you sit for hours listening, looking at the graph, and tweaking the response. However, at the end of all that hard work with manual tweaking, once you achieve a flat response at the reference SPL, you will never have to touch it again if all else remains the same. Before the SMS-1, my EP-500 sounded great after careful placement, calibration, and EQ adjustment (full, half, flat). After I added the SMS-1, the FR response was even better and soundtracks had noticeably more articulate and satisfying bass.
I looked into RealTraps and GIK Acoustics bass traps. Ethan at RealTraps is the co-owner and was very helpful. You can e-mail him pictures and dimensions of your HT room and he can provide you with advise. Their site also has a free program with test tones and graph to plot your response manually. Their traps are excellent but not cheap. GIK Acoustics (I think his name is Glenn) never replied to my two e-mails. They seem to have decent and somewhat cheaper traps. I think BrotherBob uses theirs in a modified way. In either case, buying several traps quickly stacks up the cost, and WAF becomes a real issue. Of course, you can always go the DIY approach. In my case, I decided to spend much less and bought the SMS-1 with excellent results. Both jakeman (John) and dllewel (Dave) have the SMS-1 as well, and I actually used their valuable feedback when deciding to buy mine and also when setting it up. Outlaw Audio has an excellent manual for the SMS-1 that is also far more detailed and helpful than the original manual by Velodyne. I hope this helps.
John
