Baffle Step & Freq. Resp. Combiner Help

[69stingray]

Hello everyone. I am having a problem with baffle step simulator and Frequency Response Combiner. The generated baffle step response looks correct, so I think I am doing something wrong in FRC. I am using the FRD files from Parts Express for the Dayton DA175 woofer. PE’s response curve is at approx 83 dB, so I would expect approx. 77 dB before the baffle step raise. I am getting 75 dB, two dB low.

The attached blue curve is the measured enclosure, 2,000-L closed box response from Unibox. Yellow is the predicted response with a ported enclosure (I just used Unibox’s suggested volume & tuning). Both are approx. 2 dB higher then PE response measurement (HHHmmmm, 2 dB). The green like is the baffle step response (which is at 77 dB with an approx. 7.5 dB peak and a 6 dB overall raise). White is combined.

Is the Unibox outputs being 2 dB high effect the combined response? With the combined response being 2 dB low, I am nervous it may be off in other areas also.

More info: I extended the Unibox curves by using “maintain top value” and “maintain low slope”. The Baffle Step curve was extend using “maintain top value” and “maintain low value”. I tried the “set Baffle to Zero” on the low end but made it worst.