Sorry for the delay in my follow-up. Has been difficult to find time to do a fair comparison. Thanks again for your feedback
@KEW — the A/B switch proved to be the most valuable tools in the arsenal for this comparison.
Summary: Ultimately I decided to stick with the Rythmik L12. The sound was cleaner (more details further down), and it had enough output for my needs. I also liked the flatter response curve into deep bass (<30 hz) knowing that most listening would be done at moderate levels. However, it was still a tough choice as the RSL Speedwoofer was by no means a bad performer. It significantly outmatched the L12 in output — and at $400, offers realistic, shake-the-room home theater impact and does a commendable job with music.
@lovinthehd was correct to call out that they are dissimilar. RSL is a ported output monster (for a 10 inch sub) and L12 is entry level sealed servo; a more direct matchup between the RSL compression guide design and Rythmik servo tech would be with the L12F (their ported entry level). The L12F gains the output efficiency of a ported design, but I’d be interested to know if this sacrifices anything terms of detail/clarity — many say a well designed port shouldn’t; however, this mentality is what brought me to believe the RSL and L12 shouldn’t sound much different given both subs’ claims/reviews of accuracy and quick response. There is also a size consideration that comes into play for the ported Rythmiks — they are substantially bigger than both the RSL and the L12 and that factors into consideration for a multi-purpose room.
On to the details...
Looks/Design: the RSL is very boxy and the matte finish on outside feels a little slapped on, but has better connectivity in the back (stereo speaker wire integration for 2.1) and allows for phase control on LFE input. The L12 has a much more refined appearance with rounded edges (looks especially nice in gloss white which comes at a price premium), it has phase control but it is disabled for LFE and company recommends adjusting speaker distance in A/V for phase (minor inconvenience). Both companies offer decent warranties with 5 years on the speaker, but Rythmik bests RSL on electronics with 3 years over 2. All other details you need are readily available in spec sheets/other reviews.
Output/Movies: The RSL (“conservatively rated” 350 watt) trounced the L12 (300 watt) on output given its ported design. I realize this can be observed in a wide range of specs/reviews, but I’m new to this and had no reference for what the 2 - 5 db (over 30 - 80 hz) of headroom would sound/feel like. My room is long (24L x 12W x 7.5H) with connections to various other rooms (so not ideal for containment), but the RSL had no problem dominating without degrading in performance. The L12 routinely had to be about 2.5 - 3 hours ahead of the RSL on the gain knob, and certainly bottomed out/knocked well before the RSL (which I never actually heard knock even at significantly higher volumes). The thunderous and well managed response from the RSL was very tempting for movies, but unrealistic for my situation with children at home. Enrico at Rythmik forewarned me that the L12 was likely too small, and it certainly struggled to take over the room. However, it delivered plenty of impact, and I found the sound slightly more realistic when operating at my expected listening levels. I wish I had more time to measure comparative power consumption; would have been nice to see/know the additional draw needed for L12 to keep up.
Sound/Music: This is where the L12 shined. The detail/precision that it delivers is remarkable. The RSL does a very good job, just not as nuanced. Listening to electronic or hip/hop, the two sounded pretty similar, although my wife noted she felt like the RSL was adding extra pressure/resonance in certain situations. Where instruments and effects are combined, the L12 gave a bit more separation to really deep rumbles that appeared beneath the main bass line. Listening to Modeski, Martin, and Wood “Shine it”, both produced the tone of bass notes accurately, however the L12 brought each pluck to life. Listening to Phish “Meat”, Mike Gordon lets long bass notes hang in air while Jon Fishman’s kicks keep time. Again, both faithfully reproduced the tone and overall feel of the music, but the L12 did a better job capturing what I would call the “shape” of the note — to elaborate you could hear the subtle way a single pluck/note changes over time as reverberations run up/down the sting. Finally, I cycled through a bunch of Vulfpeck/Fearless Flyers/Cory Wong to see what happened when varying combinations of Joe Dart/Cory Wong on bass and Nate Smith/Theo Katzman on drums came together. The music is jazz/funk with tons of complexity at and below the crossover point, I wanted to know if the sub could keep up. The L12 did not disappoint. To ensure I wasn’t biased or letting the integration with rest of system fool me, I took the rest of the speakers out to the mix so just the sub was playing bottom end. When I went sub only, the L12 simply sounded like a big speaker (when not being pushed to it’s peak output), virtually nothing was added/subtracted — reproduction with brilliant clarity. The RSL would do well in most situations, but faltered when trying to manage intricate instrumental bass lines coupled with speedy drum kicks. Putting the rest of the speakers back in, the RSL certainly became more convincing as the harmonics at/above crossover point were able to compensate.
Final Note: In the end, there’s likely nothing new to see here for a wily veteran with lots of prior experience. I probably would have kept the RSL if our use was primarily for movies and we had ability to crank the volume on a regular basis. All differences in terms of sound quality are the result of very critical listening, so keep in mind the RSL is no slouch with music — no one is every going to question its quality in middle of dance party/social gatherings because they will be too busy enjoying it. The L12 won for being smaller and sounding a bit more convincing because of extra low end extension, separation, and clarity.
