Originally Posted by LTD02
+1 more or less on #582.
bosso, second call, do you suspect that something is wrong here?
how do we reconcile pbc's measurements and subjective impressions with your comment in #518?
First, agreeing with Josh, the SDX test results are irrelevant. The AV drivers are at least +3dB more efficient, which, for comparison's sake renders the 3600W amp an 1800W amp, and that's just one example.
1) The PB13 in 15Hz tune with chuffing present is giving triple digit harmonic distortion, mostly 3HD, which is at 40-45Hz, and will skew a meter reading as well as a SQ presentation. It's also displaying -6dB of port compression at tune when being pushed that hard.
I've said it many, many, many times that ported subs give enough harmonic distortion when driven to max capability right below tune to be far louder than the fundamental. When this distortion is added to a multi-frequencies low freqs effect, it's impossible to discern as harmonic distortion. Some listeners actually preferred the added harmonics in tests I've conducted.
Ilk didn't show the THD below tune with the Ultra, but he did so with the TC2k ported sub, which shows over 100% THD below tune, and that was with the 105dB sweep where there was 'only -2dB of port compression and far less THD than when the sub is driven to chuffing.
2) C weighted meter peak readings of low end effects are all but useless. If you can accompany the reading with a reasonably accurate spectrograph, then the peak reading may be corrected fairly closely. The spectrograph will also show the contaminating effect of harmonic distortion.
3) The Ultra has a +3dB advantage around cross, which is where the meter will register it's peak reading more accurately. During LFEffects, below 20Hz doesn't contribute to the reading appreciably.
4) The AVs FR shows a +21dB advantage at 10Hz at 85dB. I can tell you from my tests of a 4XAV15H system in-room that there was zero compression at 10Hz when I stopped the sweeps, far higher than 85dB @ 10Hz.
This advantage expands exponentially from 10-5Hz, so we're essentially adding reference level output over 2 octaves that is completely missing from the Ultra. Any time you add those bottom octaves, the sound becomes discernibly different. The decay time of those octaves is relatively much longer. This will inevitably result in a difference in subjective comments as it's a new experience for most everyone, and, since the meter is c weighted, those frequencies will not register at all in the peak reading.
5) The 4x15AVH system has +10dB of output advantage above 40Hz, at a minimum. Now, if that system is faithfully reproducing a scene at -1dBRL, that does not mean it doesn't have enough left in the tank to "best, destroy, outshine", or whatever the descriptor may be, the comparison sub in pbc's particular room at his particular distance from sub to LP. It just means that it has enough to faithfully reproduce a given source in that room at that level and distance.
The suggestion that it can't best the Ultra approaches the absurd in my book.
6) Josh also mentioned how critical it is that the meters mic be precisely where the measurement mic was. Just a few inches could place the meter in a spot where one system is creating a _6dB peak and the other system a -6dB null, especially when the Ultra has a +6dB boost applied at 60Hz.
Bottom line is that the Ultra sounds to me like it's not capable of -1dB reference level performance in pbc's room with the source he selected to play. Chuffing, massive compression and triple digit harmonic distortion means there ain't enough sub.
OTOH, if the RMX5050 wasn't clipping, the AV15H system breezed through the exercise, and I'll bet lunch money it gave zero compression and very little THD as well.
As I said earlier... not in this universe will an Ultra match a dual, dual-opposing driver 4x15" AVH system with an RMX5050 power plant.