Originally Posted by N8G
Ok, question for the audio scientists. I was A/B-ing the SVS PC Ultra (12" ported) vs the s3000i (dual 15" sealed) with a couple of movie scenes. Both subs were in the same location (at least as close as I could get them without moving each after each test) and dialed to the same levels. My observations were that s3000i went dug deeper and gave me more discernible notes in the 20 hz - 40 hz range. The SVS however, definitely gave me much more tactile response. I could feel it in the seat of my pants through the couch and my legs through the coffee table. The s3000i does give me a rumble and you can feel it in the floor, but just isn't the same impact as the SVS. The couch doesn't shake and the coffee table isn't jumping.
Maybe I am naive, but I thought dual 15" drivers in a sealed cabinet would give me the same tactile sensation that a 12" ported would, even without any room gain to speak of. Am I being naive? The room itself is about 40' long by 13' wide opening into a dinette, dining room and living room with 8' ceilings. Essentially 2/3 of the 1st floor is open either directly or through large door ways to the family room where my setup is. Sub location is mid-wall, right next to the large opening to the living room. Could it be perhaps the configuration of the subs with the SVS being down-firing? Would that give me more gain than a partial wall?
I know everyone will say I need dual sealed or a large ported to pressurize the space, but I am not looking for foundation cracking bass. I am just trying to match the SVS 12" PC from a tactile sensation. Is that realistic from a single sealed? I guess I am surprised a 12" driver is outperforming 2 15" from an SPL output perspective.
What you are experiencing is not entirely an output issue. As Ray said, the PC 12 may have a little more SPL near it's port tune. I haven't tried to do a comparison of the two subs, but let's say hypothetically that it is possible the smaller sub has more SPL in a very limited frequency range. But, what you are describing is not specifically SPL-related. Tactile response is the body's reaction to vibration, literally air moving in this case, creating particle velocity. It is easier to visualize this phenomenon with forward firing ports. We can think of air passing out of the ports in the same way that it does from a fan.
But, even with a down-firing ported sub (where the port faces upward, rather than directly toward us), there will be an increase in particle velocity, and that increase in PV will become most intense as the ported sub nears it's port tune. The nature of the air moving through the port is an important factor in the bass tactile sensations that we feel. As the recent discussions of tactile transducers suggested, even using something like Crowson TT's can generate tactile sensations which are hard to distinguish from those produced by subs. Our brains interpret the tactile sensations as more bass.
You may need a little time to get used to the slightly smoother tactile sensation of the sealed sub, or you might find that you really do miss the TR of a ported sub. In that case, you can always go to something like a V1801. There are some obvious trade-offs between ported subs and sealed subs. Sealed subs will typically have more mid-bass SPL and may have a smoother sound to accompany the smoother tactile feel. Ported subs will have more SPL below about 35Hz, and down to their tuning points than equivalent sealed subs. And the sound/feel of the subs may seem more aggressive in the way that you are describing.
I believe it is strictly a YMMV issue. But, before deciding one way or the other, I might give myself a little more time to experience the differences between the two types of subs.