Room Acoustics Problem?

While I agree with the previous two folks, I also think that the combination of Bryston and Thiel can sound bright and forward under some conditions. If this system does sound "bright" to you, DO NOT toe the speakers in unless they are wider apart than their distance from your listening seat -- keep then parallel to each other. Also, this system can be VERY cable-sensitive. What speaker cable are you using?

Best of luck,
Joe

OZfly, I assume that you already have corrected for the ERROR added by the measuring device. If not here are the corrections. ADD the error value to measured value and review the results to see where the problem is.
Freq error
20 6.2
25 4.4
31.5 3
40 2
50 1.3
63 0.8
80 0.5
100 0.3
125 0.2
160 0.1
200 0
250 0
315 0
400 0
500 0
630 0
800 0
1000 0
1250 0
1600 0.1
2000 0.2
2500 0.3
3150 0.5
4000 0.8
5000 1.3
6300 2
8000 3
10000 4.4
12500 6.2
16000 8.5
20000 11.2

Of course this may make your upper mid-range, low treble problem worse. In that case room acaustics would not cause big boost unless you have highly reflective surface-mirror, cabinet glass or big picture frame between you and speakers. If not, thiels are known to on brightet side in low treble range. Joe suggestion in combination with near field listening, verified by trial and error re-measurements should do the trick or try different IC between Pre amp and amp.

Thanks all. I did measure at listening position and did adjust the readings to correct for instrument design. Speakers are fairly parallel to one another and I do have an oriental on the floor. But, I used a slightly different adjustment than Nilthepill recommends (with those adjustments, things look better -- there is still a big dip in the 32-50 Hz range and a 2-4 db spike at the 5k - 6.3k range but the 20k is only down by 5db -- everything else is in the 2db range with a couple of 3db issues). I am using the Stealth Premier speaker cable but agree that an alternative might be good. The low end dips and upper mid spikes still drive me nuts when I'm listening so please keep the suggestions coming. Thanks.

I have the CS6's as well but have found that the bass in my setup rolls off more or less nicely into the mid-20hz range. I am driving them with a Krell FPB-300. I have found that using different amps can cause changes in the frequency response especially in the deep bass. My speakers are also a little over 4 feet from the rear wall. I found that I got the smoothest overall response where they are now, not closer or further out from the rear wall. It sounds to me that you are getting a room interaction problem to get the spike in the 20hz region after they start rolling off in the 32-50hz region. How close are they to the rear wall?

Gregg, thanks. I'll move the speakers out another one to two feet and retest. The bass doesn't exactly roll off. At 63 Hz, it's +3dB and then it plummets to -6dB at 50, -7dB at 40 and -6dB at 32 rising to +2dB at 25 and -1dB at 20. That's strange, and noticeable. My other concern is the spike at 5k. It will take a few days to do the testing but I appreciate the suggestions.