Two subwoofers in smallish HT room?


My home theater system is set up in a 16x11x8 ft room. I currently have one line-level HT subwoofer in the front-right corner. It's a very good subwoofer (Vandersteen V2W), but it needs to play pretty loud to produce good LFE. When it plays loud, it seems to localize.

I've been thinking about getting a 2nd sub and locating it near, but not in, the back left corner of the room in an attempt to smooth out bass response and give me the opportunity to turn down the volume on the front sub.

Does this make sense, or will it make in-room bass response worse? Is the room too small for two subs?
rex
A question was raised about using subs of different sizes, but seems to have been dropped.

I was looking for a second Velodyne HGS-10, when an opportunity to buy a local HGS-15 arose. The HGS-15 was delivered by a system integrator who is very familiar with high-end equipment. He recommended I set my pre-amp to send everything below 80 Hz to the sub. Relieving the smaller KEF 102/2s of handling these frequencies really opened them up; I was surprised that the effect was the same with the 104/2s. The sub sits on an Auralex SubDude. I set all speakers, including the sub, to equal SPL, using the C scale of my Radio Shack sound level meter with slow integration. The pre-amp generates white noise for this purpose. The result is seamless open sound without boom or heaviness, and a grand sound stage with precise imaging.

Now the question: Is it worth hooking up the HGS-10 next to the left 104/2, or should I move it downstairs to use with a pair of 102/2s, and someday look for another HGS-15. The room is 14' X 19', with an opening leading to a dressing area and bathroom. The existing setup seems quite free of peaks, and the single HGS-15 is quite able to deliver the goods for movies. Stereo music is about as good as I've heard.

db
db you now own both..Feel free to experiment, by doing so can only increase your experience and may be beneficial later on..I do feel your results will have you placing the hgs 10 in the lower level..Tom
I design rooms with multiple subs often. I agree with Rives about using two subs and room modes. They know what they're doing. This is one of the hardest things to get right in any home theater. I really dislike locating a sub that's near my seating area even if the bass is great. I strongly believe that the room's low frequency room behavior needs to be looked at first (test the room, our ears can easily deceive us) and a few questions answered:

1) Were you happy with the bass except for the low output? If you were happy except for the output I'd get another bigger sub and try it out using the processors crossover. The then play around with placement if needed.
2) The Vandersteen needs it's own crossover and your main L/R amplifier as per it's instructions unless you carefully changed it's hook up. It makes it hard to use it as an LFE.
3) If you still want to use two Vandersteens (or any two subs), although very good subs, their hook-up make them problematic to use. I'd probably try two identical of a different brand. I'd need to carefully set them up by taking measurements which can be done with a simple Radio shack meter, a free audio generators through your computer as a source or a very good CD that has very closely spaced frequency bands and a piece of graph paper. It's time consuming but very enlightening about bass performance.
Hi Soundprogression - thanks for the note. This particular Vandersteen subwoofer (V2W) is made specifically for HT applications. It does not have an external crossover like the Vandersteen 2Wq subs most audiophiles are familiar with. It's a line-level input only sub, and uses the processor's crossover, so in that respect it is just like any other HT sub on the market. My processor has two identical LFE outs, so adding a second line-level sub is a piece of cake from that standpoint.

My local dealer suggested I try the route you put forward in your first paragraph. I have been pleased with the bass of the Vandersteen, but not with its output. He thinks I ought to try a single Velodyne DD15 in the room before considering adding a second Vandersteen HT sub (or dual subs from other brands). He says the combination of higher output capability and the EQ functions of the Velodyne would probably make it an easy fit. It would also not create additional space constraints.

The only problem is that adding a second Vandersteen would cost approx $1300, whereas the Velodyne lists for like $4000. :-( I'd be able to sell my existing Vandersteen very quickly, but the Velodyne is still a big chunk of change.
That's good news. I saw Richard Vandersteen at CES and I failed to look up the newer sub. I mostly looked at his speakers.

What you could do in a pinch is stack Vandersteen subs. You get significantly more output with another sub (not double but say 3-5dB. 3dB officially but it depends on how they react in the room). That's often enough to satisfy people. Kevin Voecks used to do that at shows to make sure he had enough output to satisfy a crowd.

I think you still need to look at the room behavior to find out if your dealing with a big frequency hole next to a big peak to make sure that your not fighting another battle. Adding another sub in the smae location won't help you then. If you have some time and want to learn the subject, especially about multiple subs, try Dr. Floyd Toole's white papers on the subject, http://www.harman.com/wp/index.jsp?articleId=1003.

I use a small and free tone generator named NCHTONE, http://www.world-voices.com/software/nchtone.html, from of the headphone out of my laptop to my system when I don't wnat to setup my complete testing system. With that and a Radio Shack meter you can make a graph of your system's behavior and pretty much KNOW and not believe you know what the problem is.