The OP was asking about the Rhythmik L12. Can you point to where you found CEA-2010 data on the L12 or any Rhythmik 12" subwoofer for that matter? I'd be interested.
Also, can you clarify how you were able to determine that Rhythmik subs outperform JL Audio subs? The link you provided only has CEA-2010 for Rhythmik's 15", 18", and 25" subwoofers and JL's mid-line (not Fathom) 10" and 12" E-series. Not sure how you can draw any conclusions from that, but wondering if you have additional data you could share.
I was only speaking about the subs that have been measured. Going by what's been measured, Rythmik outperforms JL on a price/performance scale. Would you agree with that? I suppose you could say that Rythmik is lying about the performance of their cheaper subs, since they haven't been measured, but I just see that as unlikely, given that their more expensive model measurements match what third party measurements show. Who knows, though.
Subjectively, I've never compared JL Fathoms to Rythmiks, though I have compared the F113 to the Seaton Submersive and JTR Captivator 2400, and the JL was the worst of that group, though it was the most impressive for its size(imo).
Some of it is just physics that dictates that JL subwoofers are almost guaranteed to be overpriced(relative to the best). They're prioritizing size(which limits performance) much more than companies like Rythmik or JTR. Let's look at a Fathom vs competitor example,
JL Fathom 113:
$5,000
19" x 17" x 19"
3000 watts RMS
-3dB @18Hz
JTR Captivator 4000:
$4,200
41" x 21" x 40"
4000 watts RMS(6000 watts for $300 more)
-3dB @10.5Hz
The Captivator also has fantastic distortion and group delay measurements, just like the Fathom, though both are very likely inaudible. The Fathom is
very impressive
for its size, but the JTR stomps it in terms of price/performance, and (ime) Rythmik generally offers greater price/performance than JTR(now that JTR raised their prices by $600). I suppose you could argue that since we don't have CEA2010 data for the JL, then we can't make any conclusions about these 2 subs
. But come on, do you really think that little sub can deliver more than 108dB(2m anechoic) at 10Hz and with less than 10% distortion?!? The JTR has way more woofage, more power, and all in a box that's 5x the cubic feet. There's no way, and even with the recent $600 price increase, it's still $800 cheaper.
You're right in pointing out that we don't have conclusive proof. But I do think there's enough evidence to say with a good deal of confidence that a similarly priced Rythmik will outperform it's JL Audio equivalent. Same goes for HSU, and PSA. I don't see that as a knock against JL, either. They're not lesser engineers, they just have different priorities that tend to run counter to price/performance(size/finish), and they're going for a more luxurious brand image(similar to Funk Audio).
Perhaps Eric could jump in here to provide more data?