Three price points, three choices.

[Turkeybaster]

I'd go diy, makes the $ go much further.

I had thought about that, and while I love the idea of a project like that I don't wholly trust myself to put something together myself first try, that I would trust myself. I have some basic wood working experience and tools, however I'm not 16 anymore putting together a volumetric rectangle to throw in the back of my shitty car. I would have to be happy with my volume and tuning calculations, my wood working skills, finishing skills, as well as paint and polish and I know that I am my own worst critic. I do however have some old car audio subs that I would like to experiment with, as well as an external rack mount amp that I have no problem going mad scientist on, however for something on the level of they Rhythmic I just wouldn't want to take the chance.

I calculate about $950 for the CI kit plus materials (not including tools i would need that I not have) vs $1,200 for the completed item. Until my skills are up ill throw $250 and let the pro's do it.

 

[Turkeybaster]

I told you what I think. The FV15HP.

Do you understand the purpose/advantage of multiple subs?

Yes..... and no possibly? I understand that the primary purpose is to reduce the dead spots in the room by introducing a second wavelength, however I still would have expected 2 FVX15's at 400w RMS a piece, while not doubling volume output, at least to match or surpass one FV15HP at 600w RMS, while also offering a more consistent bass response in more seating areas.

Am I mistaken in thinking this?

 

[Turkeybaster]

Buying dual subs at same should qualify you for a additional discount if you call any of above mentioned vendors directly. I won't expect to be huge, but ballpark of $100-200 just for making short call would be worth in my book

that was factored in to the SVS ($100) and HSU ($50) but not the Rhythmik though I had thought about calling them and seeing if they would match the SVS deal. Great tip though and thanks for the heads up.

 

[Turkeybaster]

... how about yet another option? If you'd prefer to stay within your budget and get something a little more diminutive to spare floor space, a pair of Outlaw Ultra-X12 subs might be worth considering as well. It won't move as much air as one of your 15" options, but it will dig deep, has variable port tuning, and a pair ships for... Oh, I dunno... got to be less than $1500 anyway. With Memorial Day coming soon, I should also point out that often times around holidays Outlaw offers free shipping or other sales on their subs.

Once again thanks for muddying the waters!
I haven't seen much in the way of reviews for that unit I will have to dig around, but besides even that I have found another possible option on my own. I was watching Audioholics CES2016 coverage and their Emotiva booth coverage. They have a new line of subs coming out. 12" driver with 12" passive radiator and a freaking 600w RMS class AB amp. That thing looks to be a monster, and with that passive radiator a small footprint! $700 each (Maybe a 2 unit discount?) The CEO basically said that he designed it as a friendly middle finger to Gene at Audioholics for chastising their last attempt at a HT sub for not going low enough or loud enough. That thing has great promise, can't wait for them to do a hands on review.

 

[Turkeybaster]

Hey guys! Just wanted to take a break from the thread really quick to thank you all for your personal input, recommendations, and ideas. I take them all to heart. You have been super helpful and I can tell this is a friendly and healthy community of like minded maniacs.

Cheers.

 

[herbu]

I still would have expected 2 FVX15's at 400w RMS a piece, while not doubling volume output, at least to match or surpass one FV15HP at 600w RMS, while also offering a more consistent bass response in more seating areas.

I'm gonna let one of the technical guys answer this one, because the answer will necessarily require an explanation of why. I don't think I could do justice to either.

Here's what I can tell you. My HT room is a lot bigger than yours. Open to the dining room and with a cathedral ceiling. One FV15HP provides more than enough volume. In fact, I had to set its gain down to ~9:00 for Audyssey to get it near Zero. So your issue will not be volume either way.

 

[rojo]

Yes..... and no possibly? I understand that the primary purpose is to reduce the dead spots in the room by introducing a second wavelength, however I still would have expected 2 FVX15's at 400w RMS a piece, while not doubling volume output, at least to match or surpass one FV15HP at 600w RMS, while also offering a more consistent bass response in more seating areas.

Am I mistaken in thinking this?

Yeah, don't get too hung up on wattage. There are lots of factors that go into how loud a sub will play -- driver sensitivity, excursion limit, box tuning, amp DSP... And with two boxes and drivers being equal, 600 watts will only deliver ~1.5dB more output than 400 watts.

CEA 2010 bursts are a pretty good yard stick for total output when you find them published. You can compare the FV15HP with the Outlaw Ultra-X12, although there's no guarantee that both labs measured with the same methods. There's also little indication of how long a sub rings after an impulse, which a waterfall plot or spectrograph might indicate. Jim Wilson measured the Rythmik E15HP's decay, and it demonstrates some highly impressive control. One would expect the FV15HP to measure similarly. I haven't been able to find any impulse response measurements on the Outlaw Ultra-X12 (or any other Outlaw sub), but all I can say is they are anecdotally well-reputed.

To answer your question more directly, I have read that the FVX15 matches the FV15HP with 2 to 2.5dB less output. So yes, having two FVX15's will probably give you more output than a single FV15HP (as having two subs generally nets an additional ~6dB).

But, there's a bit of a learning curve and some additional purchases involved for managing two or more subs. You'd need a DSP, a calibrated measurement mic, and something to plug that mic into. A popular route to take is a miniDSP with 2way Advanced plugin and UMIK-1 microphone, using the freeware Room EQ Wizard on a Windows PC to handle the measuring. There's an excellent beginner's guide to REW available.

Long story short, if you enjoy fiddling and tweaking, get two subs. If you prefer automatic, get a single sub.