I've been active in this forum for 11+ years. In many discussions over the years, many things newer members take completely for granted were not known and many more were mysteries of physics that were thoroughly debated until a consensus could be arrived at through formulae and data.
Many if not most of those discussion were what many newer members here today would obviously find unacceptably heated. We just called them 'spirited debates'.
Brian Ding, to my knowledge, is the only principal of a product mentioned in this thread who is a degreed engineer in the field. Dr. Hsu is obviously degreed as well, but I'm not certain of what his degree is in. Brian contributed truckloads to those early discussions and never resorted to the sort of abrasiveness, bullying and general whining some of us have come to see from Tom as his signature posting style. Brian always added to the discussion without ever using the debate to sell his products or lording his education over anyone, and all of this despite the fact that English is not his first language.
Thanks, Brian. I owe you a lot where this subject is concerned.
IMO, FWIW, YMMV, if the decision to buy a sub comes down to anyone vs Rythmik, I'd opt to go with Rythmik, no hesitation. Brian is a solid engineer who has built very good products from an engineering standpoint and with an appreciation of the arts, which is a rare combination. He as stand up a guy as I've met in my electronics travels, so I personally would not sweat reliability of his products in my decision.
I wanted to add my 2 cents regarding the sine wave sweep, shaped tone burst testing results data and its interpretation. I've been building and measuring subwoofers for close to 10 years and I have never used sine sweeps or band-limited bursts to assess performance. I use the most demanding soundtracks. It has always struck me odd that measurements folk have a mind that soundtracks are somehow not good input to test performance.
The hang-up over a 5dB higher sweep capability, despite massive compression, unacceptable non-linear distortion and grossly distorted frequency response has reached the point of just being silly nonsense. My subs is 1.1 of your sub because the sine sweep says so. Wow.
If you just have a glance at the performance at 20 Hz (a kinda important frequency for the subs mentioned in this thread), it's plain to see that the sweep increase from 115dB to 120dB shows zero increase in output, yet harmonic distortion quintuples... all so that an octave of bandwidth can play a few dB louder before the typical 80 Hz crossover LPF shuts down the top end at a rate of 24dB per octave.
So, the sine tests show us that limiters allow one to bump the sub a few dB while introducing triple-digit harmonic distortion and distortion of the native frequency response by 7dB with input of a sine wave sweep to 10 Hz and debaters here are seeing only the few dB out extra output and touting it as a good thing. So, what happens when you play WOTW, HTTYD and hundreds of other soundtracks with content to 3-10 Hz, some of which effects are centered <10 Hz? Who knows, as it's never mentioned, nor has anyone besides Keith Yates ever used actual program to test performance.
(BTW, Yates' tests in a series of articles tilted "Way Down Deep" are archived and a simple search will find them. I recommend reading through it. It's easily the best subwoofer testing ever by a really smart guy.)
The subs mentioned in this thread are not 120dB subs. Maximum output at the expense of bandwidth is all too common. You meet the maximum output metric by using multiples, not by choking the low end and pushing your sub beyond its capability. This is not a debatable point.
Bottom line, the Rythmik sub is first rate and Brian will stand behind it. Buying one with plans to add a second is a good plan. I don't see a down side. Of course, that's just my 2 cents, but I chose to add it to this thread because of my opinions on the integrity of Brian Ding, who doesn't get the credit he deserves on these boards.