subwoofer question

Bob, Marty so if i hear you correctly youre saying there is no stereo info or localization info below 80-90Hz. So the superiority with two subs would be cancellations of node and downside if you take money into account would be you could buy a better single sub?

I've extensive experience with that subwoofer. On it's own, they are fast, accurate, musical, and dynamic. They are good subs overall, yes. You can, however, bottom them out/distort them with strong movie material. That is the downside to any of those MX series, accept the MX5000! That's the truth. That said, two of them, will likely ameliorate that potential issue, help cancel out any distortion between them in mono operation, provide more efficiency into your system(regardless of how you configure them), and more output for sure. However, as far as volume of your room goes, really, one should be enough for that small space. Infact, I wouldn't even mess with two of thoose in that room, I think it's a space killer - unless you can get real creative. It's doable, but usually cramping your space.
For the money, at $900 for the pair, that is a a good deal, as things go. You won't get hurt, and can sell em later, and get the money back.
I would be looking for a simplified solution, myself. Even though you can do more with multiple subs, I'd simplify and EQ in that room. I would NOT be looking for subs placed around the room, in that limited space. Balance is important here, as always.
I would probably say, buy the deal, and see if you can get by with one of them. You may find that one sub is all you need. Place it up front next to your center channel/mains, and be done with it! It will integrate well, have proper phase for all seats, and perform well in that room, with a good EQ integrated into the system/processor.
I guess I'm saying that, if I was in your shoes, yes, I'd go try the M&K's, and see what you think. You'll only ,likely get less accurate bass potential from other choices, and they're easily sold if if you change options later.
This way you'll know what the M&K's are capable of in your room, in your system. Then you can try others later if you want.
Yeah, I'd try em. M&K makes a good overall product, that's very durable too.

Perrew,

I've done a/b comparisons with my old Velodyne subs wired for stereo then re-wired for mono. At 100hz, I wasn't sure that I could tell the difference between mono and stereo. At 80hz, I was sure that I could not tell the difference. At 125hz, I thought that I could and at 150hz, I was sure that I could hear a difference.

FWIW and, as always, YMMV.

Marty

Perrew,

These comments are for HT only, as per your description of your system.

Does your HTR have DRC (Audyssey or similar)?

If so, the DRC will both optimize the x-over function and provide smooth FR over the entire audible range (which obviously includes all the room induced nastiness in the bass). Therefore, the "smoothing effect" of properly positioned mulitple subwoofers is much less important.

Once you're at this point, forget about smooth FR.

What's (mainly) left is clean output capability. Since I use Rythmik subs, I'll use them as an example. A pair of 12" Rythmik subs provide roughly similar clean output capability as a single 15" Rythmik sub. The 12 inchers are $749 per unit and the 15 inchers are $899 per. If your main focus is clean SPL capability (as, IMHO, it should be in your circumstance), the single 15" unit is a better value. As Bob noted, you could always add a second unit later - for any reason.

This isn't the most sophisticated analysis, but IMHO, it doesn't need to be.

BTW, from my previous post, you should note that, at 150hz, it was easy to localize the source of the signal. If you want to x-over somewhere near this high in frequency (and there are several reasons that you might, given specific equipment in a specific room), then 2 subs wired in stereo is important.

Also, please note my caveat. Under reasonably controlled conditions, I could not hear signal localization once I got a bit under 100hz. Other people may be more sensitive to this. It's easy to extrapolate from our own experience and assume that it's universal, but this may not be so. Hence my ever present YMMV.

Good Luck.

Marty