Ah, audio. We all want objective criteria to compare on, but it's never straight-forward what that means in the real world, is it? I suppose that's half the fun.
I appreciate the response Enrico! But I must admit, I find myself again a bit hesitant about what the right move is. Cost is a factor, but a clearly superior result would be my priority.
What I find really tricky just reading around, is trying to aggregate and weigh different factors into a real-world end result.
Here's a non-exhaustive list of factors I'm thinking about. In particular, with dual 12" paper cone vented LVX12s vs. a single 18" aluminum cone sealed F18.
Distortion. Reading responses like
Brian's discussions of THD vs. other sources of distortion here, it seems to me that distortion modeling is difficult to accurately measure, chart, and interpret. Presumably, all Rythmik subs are as well-optimized as they can be, cost-savings factors aside?
Driver size. All else being equal, smaller drivers should be capable of better transient response, no? I've noticed
some discussion around the F8 talking about this, with its 8" drivers. Is this noticeable between a 12" and an 18" driver when playing music at the same (say, moderate) output level, in the same (say, 16-60 Hz) frequency range?
Driver material. All else being equal, paper drivers have less mass than aluminum, and thus are capable of "
slightly better dynamics at low to moderate volume levels".
Enclosure type (sealed or vented). On the one hand, "
[Rythmik's] recommendation for a subwoofer for music are [their] sealed Direct Servo subwoofers. If your interest is also home theater as well, one or a number of [their] sealed subwoofers will still be an ideal choice. If you are a home theater enthusiast on a modest budget and don’t listen much to music, you might consider one of [their] vented subwoofers.". But on the other hand, "
Don't be fooled by typical comments about vented subs lacking accuracy. [Rythmik's vented] subs are tight and musical." So there's a difference. But it's not huge?
Frequency response and masking effect. Perhaps the biggest advantage of bigger subs is lower frequency reproduction. But how often does that matter? "
Due to the masking effect, deeper bass will often not be noticeable, unless at very high in amplitude as a special effect. Of course, there is music with high amplitude bass that will mask very low bass." But on the right recording,
low response is necessary to capture all ambiance and dynamics. Does the F18 accomplish this noticeably better than dual LVX12s?
Amp type and power output. Rythmik offers class A/B, class H, and class D (Hypex) amps. Not much to say here, as the LVX12 and F18 both use Hypex, and are both sized similarly to their driver size (unlike the LV12R, which uses less power for its size to cut back on cost).
Room modes, etc.. There is no end to discussion around how the room itself affects what we hear, and it's plainly very important (
here is a short bit from Rythmik about it). One frequent bit of advice I see is that multiple subs, when placed carefully, can help with evening-out frequency response (room modes) at different points in the room. This is of course not the only factor, but it's an important one.
Perception.
Brian makes some good points about this. My experience over the years with trying various headphones and building amp and DAC kits is that I prefer neutral reproduction overall. But do I feel differently about bass reproduction? I want things that may be opposed, like more "slam", but also more room ambiance. One thing I can definitively say is that the LV12R made all other subs I've heard (which includes nice commercial movie theatres, but not much else for home stuff) sound like boomy crap to me, so clearly I value transient response. Maybe I won't know what sub(s) I prefer until I live with them for a bit...