Originally Posted by bossobass
Please apply an equal amount of power to both drivers in your example and post the graph.
Now your trying to see how sensitivity plays into this bosso, I was referring to frequency response, not what happens at a given power input.
Here I'll post the graph of the 15" TC5200, the 18" one still has less output at 20Hz, but things look different because you can't see the effects of its excursion as well since its cone is so much bigger. The 15" model has an fsc of 21Hz while the RL-s15 has an fsc of 25.5Hz, heres how they look in a 1000 cubic foot box being pushed to near max output with 1500 watts of input power. I have factored in the inductance, but the RL-s15 still has a hump without it, its just smaller. Here I'll extend my results down to 5Hz so we can see that yes, the TC5200's slow rolloff causes it to take over again, at 20Hz though, the results are quite apparent. Furthermore, the effects of inductance in a system can cause the frequency responses to behave quite differently where the fsc and qtc are the same.
Here I'll go back to what I said earlier, about a driver with a Q of 0.5 being down more at 20Hz than the one with a Q of 0.9 with similar or even lower fs's in an IB system (so of course the fs will nearly equal the fsc). its hard to find any drivers that fit this bill exactly, but I'll choose the ficar Q15, it yields a Q of 0.508 in an IB but its natural qts is 0.493, anyway, its right around 0.5, also, its fs is 24.9Hz, a tad lower than the RL-s15 with its fs of 25.5Hz.
Now, the RL-s15 still has a lower F3 (naturally, the math still supports that) and its down 6dB at 20Hz, whereas the ficar is down 10dB at 20Hz. Once again, you can see that the more gradual slope of the Q15 causes it to take over down low, around 8Hz. (I am not saying this to inform you bosso, but to show what I understand).
Actually, the math supports the models in winisd perfectly, how do you think it calculates its F3? From what I can see the math is by no means "more accurate" at least, unless you are referring to the discrepancy that I had with ThomasW saying that at 25x vas, fs = fsc and qts = qtc which from the how it looks to me, it still can need more volume than that to drop more and with less volume, it may not change significantly, still I had no problem with the generalized statement as I said earlier, pretty much any driver will look good at 25x vas for IB.
Welcome to the realization that more motor or a higher sensitivity driver ain't always mo-better.
Actually I noticed this a long time ago, all this talk of Q kinda brought it to the surface. There was a time that I was interested in trying out an RL-s15 a little over a year ago, and that is where my true journey into the Q began.