Originally Posted by BiGBADDABOOM
That's incorrect, I already used the burst number (+3dB) from Ilkka's measurement for the PB13. My comparison was valid.
If his 130dB claim is only "should" but not reality, then his 127dB RMS spec is also "should" and thus also not reality. You can't have one and not the other.
There's nothing incorrect in my post.
How could anyone's "should" be reality? Until it's actually measured, it's "should". What part of that confuses you?
You started out mistranslating Ilkka's numbers into CEA 2010 burst numbers, you used a DIY PR'd sub that's down -5dB @ 20 Hz to compare to the flat-to-20 Hz tuned ported Cap @ 20 Hz, errantly looked at driver X-max to compare ported and PR'd subs at tune where their respective drivers are at minimum X-max and then switched to a commercial sub with a driver that has 35% less displacement driven by -8dB less power with yet another errant comparison that lacks sufficient data to do anything but say "should" in the first place.
Try to focus here: I do not disagree that Danley, Hsu, Chase and now JTR have and still are engaging in whacky numbers games.
This should have been painfully obvious in the case of Danley claiming 120dB at 12 Hz, which turned out to be off by a factor of 20 times or more. Yet, fans of his horn remained unfazed and supportive.
Hsu popped out of the gate claiming 125dB CEA numbers, the measurements revealed 3-4dB less. Yet, fans of Hsu say 'close enough for government work' and remain avid fans.
Chase, although he's measured every ID sub available over the past 8 years and even took to rating them by his own unvetted system, can't seem to muster the technology to measure his own sub. He also has thrown out all sorts of output claims, none of which have been verified. Yet, his fans claim there is a plethora of technical data available (maybe one has to purchase a special map to find them?) and they remain undaunted in their praise.
Now, sadly, JTR has jumped on the wild and crazy numbers wagon. Looking at the claims pragmatically, if the Hsu was CEA burst 1M clocked at 121.7dB max, I don't have a problem believing that 50% more cone and +9dB more amp won't reach 130dB under the same test regimen.
I do however have a problem with the compression sweeps graph JP posted of the "2011 Captivator in 15 Hz tune with 4096W", and it may offer some insight into the claim JP made regarding the CEA guesstimate.
The CEA numbers are based on the THD limited output resulting from a shaped tone burst signal. That test pays no regard to compression. Since the sub should be at a THD minimum at tune, one could drive the sub well into port compression with no effect by the THD limitations of the test.
The posted Cap compression graph was so baffling to me, I decided to transpose the data onto a TrueRTA graph that's scaled to what we're all used to seeing in a compression sweeps graph.
First, I'll note the problems I have with this 'data':
1) It's amazing to me that the folks who created the Tef system would have decided on a graph background of royal blue and traces you can only read if you're wearing the Hale telescope around your neck with a vertical scale of 10dB per division. WTF?
2) As if that weren't bad enough, JP stretched the graph horizontally so as to all but completely render this graph unreadable, as well as to give the impression to the casual reader that the sub has a near ruler flat response.
3) After tediously and meticulously scaling this graph to a readable form, several things struck me:
a) The 16W sweep, above tune, shows minimal compression, but every sweep after that shows expansion.
b) The 1024W sweep shows 3-4dB of port compression, yet, when the level is bumped +3dB for the 2048W sweep, the port compression drops to 2-3dB. This is a new phenomenon to me and I certainly wouldn't mind hearing the explanation for how it might be possible for this to happen.
c) The 2048W sweep shows 2dB of expansion, almost uniformly across the BW above 20 Hz, yet the 4096W sweep shows less than 1dB across the same BW. IMO, this probably means that none of the Watt values in this graph are accurate, and it makes me wonder why a dB increment scale wasn't used to describe the sweeps. In any case, there is no explanation with this graph, so it would again be nice if one was made available.
d) Sweeps 1-5, starting at the bottom, show a normal progression to compression from the port, but the next 2 sweeps take a rather drastic departure from that trend to a new trend that certainly would seem to lend itself to a higher output reading at 15 Hz (where the graph is flagged) than otherwise, Had the first trend continued.
I agree with you that once any company official posts technical data regarding the performance of any of his products, he is then open to scrutiny of that data.
Having said that, I stick to my first admonition that you have your ducks in a row before you post and learn to acknowledge your mistakes before moving on. If JP decides to respond, but adopts your 'yeah, but, yeah, but' method, you wouldn't accept that, nor would we ever get to the bottom of anything.