By reading this forum as well as http://www.hometheaterforum.com/htfo...?s=&forumid=46
and other's, I have increased my knowledge and understanding of subwoofer and in-room bass response theory.
Here is my story:
My HT is in my basement. Carpeting ontop of a cement slab. Thin wood paneling on top of cement cinderblocks. Large 50 x 22 x 7.5 ft basement, with a portion of it finished off as the HT room. In short, this room sucks for bass. The cement/cinder block walls/floor create the ideal environment for resonance peaks, room modes, and other undesirable bass effects. The carpeting and sectional sleeper sofa absorbs a bit of the high freq's and leave the boomy bass behind.
My Odessey Begins:
Yamaha YST-SW200 Subwoofer http://www.yamaha.com/yec/customer/manuals/14YST-S3.PDF
Bookshelf speakers good down to 45 hz.
Panasonic SA-XR45 Digital Amplifier with cross over freq set to 100hz.
The Yamaha subwoofer is not very impressive with its stats: dual 7" woofer's, yamaha active servo design with 100 w amp. Specs say it goes down to 20 hz but at -10db down. If I had to guess, I would say that the -3db down point is at about 28hz.
I used etf software to measure my room. You will see several of these plots in this thread. You cannot directly compare them since ETF tends to normalize the highest measured peak to 100 db. So look at the trends not the absolute y axis measurements. I have a RadioShack analog SPL meter which has a mic output that works with ETF software. ETF software also has a calibration file for the RadioShack meter.http://www.etfacoustic.com/
The ETF calibration file for the Radio Shack SPL meter does not have values for the lower freqs. You need to look at these postings to adapt the ETF cal file for low frequency measurements:http://www.hometheaterforum.com/htfo...tf+radio+shack
Figure attached is my starting point. Note that the plot is truely awful. Signficant peaks and nulls measured at my primary listening position. Almost no low end response measured at all. This sounds as bad as it looks: