Originally Posted by chucky7
Well, S3600i was tested by HTR, not data-bass... so some would say that the numbers are not comparable... IIRC, some have said that Brent's numbers are inconsistent... Since S7201's numbers are derived from those of S3600, that leaves a larger margin of error. That is why I said "Even if..."
10dB advantage is twice as loud. The Cap 4000ULF has more than double the output below 31.5Hz.
I'm not quite sure about the numbers either, regarding Tom's comparison of the S7201 to dual v3601's, so I had just extrapolated some frequencies where I thought that the S7201 might have some advantage over the Cap 4000. ( I believe that Tom was talking about low bass frequencies, as even S3601's would beat V3601's in the higher bass frequencies.) I concluded, as you have, that the Cap 4000 would still have a very serious SPL advantage in the low frequencies, below about 25 or 30Hz, and continuing all the way down to a little below 10Hz.
I think that the reason tvuong said that the Cap 4000 would be more than twice as loud, where it had a 10db advantage, is due to an idiosyncrasy in the way our hearing works. According to the Equal Loudness Contours, which chart human perceptions of loudness, at 1000Hz an increase in SPL of 10db is perceived as being twice as loud. That nominal doubling in volume is consistent throughout our normal hearing range of about 400Hz to 4000Hz. But, our perceptions of loudness change somewhat at both ends of the human hearing spectrum. At 30Hz and below, for instance, an increase in SPL of only about 5db is perceived as a doubling in loudness.
So, a 10db advantage in SPL from about 30Hz down would be perceived as about 4 times as loud (2 X 2). That's why even relatively small increases in SPL in the frequencies under about 30Hz can be so important, and why ported subs like the Cap 4000, can be such powerhouses. Sealed subs just can't go that low, that loud, compared to the really powerful ported subs. Of course, depending on the room and their placement in it, they can sometimes obtain enough room gain to still be more than satisfactory in those low frequencies where ported subs have the edge. Ray's (imureh) recent experience was a good example of how helpful that room gain can be in a small room and at close range.
I can't imagine how big a sealed sub would have to be to beat a Cap 4000 under about 25 or 30Hz.