Have you looked into REL and JL Audio subwoofers? They have won 2006 and 2007 TAS subwoofer of the year awards. My suggestion is the Rel Britannia B2, very musical and integrate really well. Disappears in my room and sounds un-box like. Read the TAS review on the B3.
Are you a DIY'er? I made my first infinite baffle subwoofer about two years ago, due to what people were saying concerning the QUALITY of the bass. The bass is EVERYTHING you could wish for!!! (and then some) It is very "different" than bass from a box.
Here is a link to wet your appetite. Be sure to read at the bottom of the page concerning the "quality".
Do a search on Google for "infinite baffle subwoofer"
Try a sub from Genesis Advanced Technologies. The G928 is awesome. Price is a little high but well worth it. If you are on a budget, try a Z Sub from BG. Best sub I have heard under $1200. Fills the room, without a boomy box feel. It has 2 10" drivers, fast enough for music, and powerful enough for good movie watching.
I cannot agree more with Bob Reynolds on setting up the sub.
Apart from that, bass traps behind the speakers at the corners would substantially improve bass definition. I have read from a few posts that they don't help in some rooms but once I took out the bass traps from the corners of my room, the definition was lost and bass got considerably loose. That was the point when I figured out I cannot live without those traps.
Yes! What Bob Reynolds is infering here is correct! You simply don't know what all the variables you were dealing with are, and their impact (no pun). Single 3 biggest issues for sub performance is location, location, location--then setup, level matching, phase with speakers/seating, and EQ'ing!!! In your still relatively smallish room, I suggest passing on the Arcam (which lacks severely needed EQ and DSP room correction features! Any relative potential great sound quality will be mostly voided by the likely bombastic room mode problems you'll likely have, as well as other acoustic issues. That's my perspective. Infact, in all these smaller acoustic spaces, that's one of my main issues! That being that even the best potential audio equipment is necessitated by needing EFFECTIVE room correction or EQ'ing! Most high end gear doesn't include much here(yet). I'd like to see more, because it's a HUGE ISSUE! Food for thought here. Yes, the Arcam is an otherwise good sounding piece, on it's own. But then what about the extremely difficult acoustic issues you'll be faced with? That's the dilema, IMO. As for Subwoofers, and your original post, if you have to go with one sub (not knowing sub placement and setup), I might suggest you won't go wrong with the Paradigm Servo 15--especially for the money!! You'll spend more on a sub, and not get more really. Overall impact, extension, lack of distortion, tightness, relative accuracy, quality, etc. That's my blind suggestion.(unless you don't end up with a system EQ, then look into others like Velodyne, with Parametric EQ feature) And I've sold/used a lot of subs over the years, and don't think you'll beat this, overall.
"honestly the signal from my two front channels will mostly be absorbed by the couch"
No this won't compute much here. Bass modes will still abound, even with the largest of couch and furniture infront of the speakers, regardless of what speakers the bass is coming from. The room modes will still excite, and be audible.
"open ended on three corners I doubt the room modes will be that severe"
Doubt? Yeah, if you get in there an measure (and listen) through the frequency sweeps, you'll be able to tell where you're at--which is the only way to tell. Yes, possibly, depending on seating arangmenents, you may or may not be able to get away with good fidelity and smooth response, in some possitions. But you gotta measure and test to find out, yes. I've not seen the room, but Know from experience what usually ends up is modal problems at certain points, regardless of how open the room is. I hope it works out very well for you however. I recently did a lawyers home theater in the main living room, that was open on both sides of the listening space, and the room was 21feet deep x over 33 feet wide (43 in once spot)to the open spaces, with a 10-11 foot tiered/coffered ceiling. After running through all the test frequencies, and test material, the owner strongly concured that we needed another pre/pro in his system--one that had a parametric EQ built in, at the time. Problems solved, the 3 main bass mode problems were eliminated (over 20db boost at two frequencies!!!!!...bombastic to say the least!!!!...not hi-fidelity). Anyway, it's always a consideration. Nonetheless, I do hope you get better results with your Arcam option, if you go that route
The best of the best of the A$$ KICKIN BEST subwoofer you will ever get PERIOD- JL Audio f113 http://home.jlaudio.com/products_subs.php?prod_id=371
I have tried them all and this is the most bang for the buck and musical too- I just bought my 2nd one Read what Larry Greenhill from Sterophile had to say about 2 of these bad boys with 1 I was in bass haven but 2 well we will see tomorrow Good luck
The JL woofer looks impressively built - so this may be a good start. Nevertheless, if you want to watch music DVD at audiophile quality distortion levels (not just impressive volumes by moving copious amounts of air, as in car systems or war movie such as in U571) then you may want to enquire about the Xmax (one way movement at less than 10% THD) for this driver. I have not found a quote for this specification which matters to audiophiles whilst only moving air matters to impressive car system and U571.
As far as I can tell, JL use the "overhang" Xmax method which when doubled they cterm as "linear peak to peak", which is simply geometry based and ignores the voice coil offset, magnetic field asymmetries, suspension problems and other driver defects (The 10% THD Xmax method has issues too, but at least it is much more rigorous)
JL claim the linear peak-to-peak excursion is 2.7 inches for the F113 (constant number of VC turns in the gap). EXTREMELY impressive but how linear this is one can only begin to guess...geometry is geometry and it is not sound!
JL's data is so impressive you could think that famous driver manufacturers like Volt that sell expensive drivers (with far less impressive specifications) do not know what they are doing ....but I doubt it somehow!
So be careful, despite the rave reviews this is a car audio speaker adapted to HT...perhaps the Hi-Fi speaker industry has some tricks to learn from this newcomer ...perhaps not.
Shadorne makes some valid points but as with everything being equal in HiFi, let your ears and body do the thinking for you not the stats. Car audio is harder to make sound good than home audio is and since when does true bass not move air?
Indeed - I just looked at your impressive home HT system and the quality of your gear is a strong endorsement for the quality of the JL F113 sub. I expect we will continue to hear great things from JL. Sorry if my cautionary note was only based on what I read and saw on the website...I hope I made it clear that I haven't heard this sub and was just so amazed by the extremely impressive specifications that it kind of threw up a cautionary flag and I couldn't help but add two cents.