Testing the SVS subwoofer on sinewave tones with the main stereo speakers resulted in a 10dB dip precisely at the sub's low-pass filter (crossover) cut-off point at 40Hz.
(shown in orange on the graph to the left)My apologies for the small size of the graph. A limitation of the website's standard page templates that I haven't been able to overcome.
Raising the low-pass filter setting on the subwoofer amplifier from 40Hz to 60Hz flattened the response perfectly at 40Hz. (Shown in blue)
The blue "cliff edge" is @ 15Hz!
Finally, adding in the RS SPL meter correction figures filled in the shallow trough at 90Hz and tilted the extreme bass line upwards into a ski jump ending at 15Hz.
(shown in red)
The response falls very rapidly beyond this point. The complete graph covers from from 10-150Hz on the horizontal axis. The three heavy lines represent 60, 70 & 80 dB on the vertical axis.
The RadioShack meter has a well known bass roll-off which must be corrected for to achieve reasonably accurate results. But at its low retail price it still an invaluable testing tool for the audio enthusiast. The correction figures are listed on the SVS website.
This final smooth, virtually flat frequency response is quite remarkable. Future adjustments could be made to the phase. To see if that makes a worthwhile difference.
I put my excellent result down to the use of a 30 foot long attic room with typical sloping walls/celing. A listening room such as mine has few parallel boundaries to support standing waves. Which would otherwise cancel or reinforce narrow bands of frequencies. Usually leading to deep troughs and peaks often exceeding 20dB in total rise and fall.
The smoothness of the frequency response in the bass is also a tribute to the SV Subwoofer's in-room response. Note the inbuilt house curve popular with film fans.
The link below is to a graph of the semi-anechoic response of the family of 3 SVS PCi subwoofers. Of which the 16-46 is the largest and lowest tuned. It makes an interesting comparison with my corrected in-room response.
http://www.svsubwoofers.com/subs_pci_performance.htm
