If you had 1K to spend on a Sub

Maybe try to redo a sub crawl before you spend more money. My living room area is a bit over 2600 cu ft and the STF-2 works well. I had to try a few placement options for it to sound right, but I'm more than happy.

If not, I'd go Rhythmik.

Do yourself a favor and step up to the F15, another $100 for another 2-3db output. $989 delivered from Rythmik. I purchased one last August.

I am very happy with music on the VTF-15H and it was 1018.00 shipped to my door.
Can be tuned to your satisfaction and I see people saying they might get 2 but one is plenty for 4500sqft.

For that matter, the Rythmik FV12 has about the same SPL as the F15, and a good bit more than the STF-2. Based on all the testimonials so for for the FV12, it should have much tighter bass than the STF-2.

If you feel there is enough output out of the HSU...then the Rythmik F15 will give you probably a little bit more, plus sound much cleaner. The HSU VTF-15H will give you more output than the sealed F15, but it may be a little less accurate. I went from an F15 to an FV15HP. There is a slight difference in sound quality... both are clean, but the F15 was just ridiculously accurate. I think it even turns some people off because they are so use to bloated bass. Since my room is over 3000 cubic foot and open, I had to upgrade. The FV15HP does much better in my room now. I sacrificed some extension and sound quality to go ported, but let's face it, any extension I sacrificed in this large room wasn't being put out at much volume in the first place so that is really a non issue.
You have a smaller room and even though it has doorways I suspect the F15 will do well. My room has more than doorways...it is completely open. I could get some good bass in the listening positions. The problem was it couldn't fill the large space and when I really wanted to jam it would stress a little bit. The FV15HP breezes through it. Not sure this all matters to you since your room is smaller and it should do fine though. I would def. go F15 over F12 for the small amount more you have to pay. It's almost silly not to, unless you are really tied to some sort of size restraint. Good luck and enjoy the hunt.

Well you can leave the vtf15 sealed, single port with two different EQ modes or leave it wide open. I have two and they sound great single port with switch on eq2.

I would also consider a Epik Empire, SVS and Rhythmic, but what you plan on using the sub for, types of finish, space available,flooring the sub will sit on, etc all have some play in the end decision.

I have a lot of room, so the size of my vtf15s wasn't a big deal.I was also able to listen to different models which helped my decision.

I'm sure you will be happy with all the subs in this price category. I do find those who do listen to movies end up needing more than one sealed sub to get that effect they are looking for.

Did you actually set your sub in the main listening position, yes elevated to ear level where you sit, and then crawl around at 'sub' level to find Exactly where it sounds best? Listening to your favorite bass heavy music, of course. This will work for one listening position in almost all circumstances.
I'm a firm believer that you can get the most possible out of any sub, in any size room, at any budget, by using this method. It's literally finding the best spot in the room, taking to account your room. Noone else has the same size room, furnishings, floor coverings, placement ,speaker size and location, openings to other rooms, wife acceptance factor, etc... ad infinauseum.... let alone the single most important factor of all... your ears, without spending a single cent. Not that I'm cheap or anything, but you've already spent hard earned $$$.. get the absolute most out of it before spending more.
This will not work across multiple listening positions in a large room, but it's not about that... it's about getting the most out of what you already have at one listening position, and one only. Then if you decide you need more, for more output at that position, or a more even (or just more) bass response across more seating positions, or just want more in the alpha seat, that changes the equation. Exactly what issue you want to address then will depend on the issues you face then... more even bass across multiple seats vs. just more bass at one seat... hard to determine until you get there, but make darn sure you're getting the most out of what you already have.
hope it helps even a little,
Joe

I just ordered a pair of Rhythmik F12se a few days ago. Unfortunately some of the sub parts are on order so I'll have to wait a couple of weeks. I'd have gone with the F15's but I needed a smaller footprint. Waiting almost-patiently.

Question .... when using a pair of subs, how would one go about doing a sub-crawl?

If I had 1k to drop on a sub it'd either be a hsu vtf-15h or ed a7s-450, leaning towards the ed personally as I prefer sealed.

Well, there is no way any of these subs will do it all due to room modes. I have done an extensive amount of research and measuring that proves multi subwoofer placement is essential for a flat response.

It would be a total waste of money to spend 1,000.00 on one sub if you really want a flat response at all your seating positions.

My advice would be one sub midway on all four walls, or corner load four subs. You can pick up four BIC-200's for 1,000.00 shipped and they will get you much better results than one 1,000.00 sub.

Anyone who touts a flat response with one sub is measuring from one mic position, not multiple seating positions