Originally Posted by basshead81
If the sub put out a passing 98db @ 12.5hz 2m rms, then I dont see how it would not have useful extension down to 12.5hz in room. I think its up to the folks that actually own and have herd the FV15HP to determine if your so called caveats should be considered. From what I have seen reported, port chuffing is not nearly as big of issue as some of you make it out to be.
You and the Bee guy seem to be arguing for the sake of arguing.
Luke got it right and it seems to me that, although this should be a no-brainer, and Luke explained it as simply as is possible, the facts are just being ignored.
For any ported sub, max burst at below tune, if and when it's even possible to register a number there, is completely irrelevant to actual use of the sub. It is, as Luke said; "IMO hitting at reference refers to frequency response as much as output. So if you had 6 clustered xv 15's in ricci's room they would be 10 dB down at 12.5 hz relative to 20hz. So you would have to be running at 10dB over reference to have 12.5 hz at reference, or you are going to boost below tune 10 dB, which sounds like a bad idea. Scores for this thread shouldn't be given below tune IMHO."
You don't get to select a single frequency and base your assumptions there. The number being looked at for max output @ 10 Hz is the subs max capability at that frequency. That would have to mean that the sub is being pushed to max across its entire bandwidth, which presents an entirely new frequency response than its basic response.
It also presents a lower maximum output curve because LFE effects are wide spreads of an infinite # of simultaneous frequencies, lowering the overall maximum output.
Compare the basic response to the max long term output response and even a first-timer can see the radical response difference. In order to retain max output at 10 Hz AND the basic response, you have to EQ out the max output capability above tune. Otherwise, you are still down -25dB @ 10 Hz from the subs peak performance bandwidth. When calibrating sub levels, the highest SPL will dominate the reading and, in this case, that's obviously at 60 Hz, not at 10 Hz.
What determines reference level at 'x' Hz, as Luke pointed out earlier, is native response + room gain profile. Period. Commercial subs employ limiters that make native response an infinitely moving target from basic response to max output response based on output level, which changes constantly with playback at reference level, unless you plan never to push the system of however many subs until the limiters kick in, which is a highly unlikely scenario.
It doesn't matter how many subs are used. What matters is the native response + room gain and the desired playback level. Multiples are, first and foremost, to reach the desired playback level without pushing the system to a new and completely unpredictable response. Using multiples of a sub to "smooth the frequency response" is tossed around like a law of physics and is usually the last resort excuse for buying more subs. Multiple sub placements does not guarantee a smoother response unless there are infinite placement choices in the room and enough subs to reach the desired playback levels without radically changing that coveted response.