Mix and match subs?

Unless you’re hell bent on its looks I think you’re nuts for considering the SF sub at $3k.  First, SF is not a premier subwoofer company (as opposed to Paradigm that makes some of the best subs extant IMHO), and the Gravis lll only goes down to 25Hz (-6dB), which probably is no better than your Paradigm.  And BTW, it pisses me off SF doesn’t publish a -3dB spec, which inhibits direct comparison with others that do and only makes me think they’re not proud of the number.  Second,, it’s a sealed sub that’s a different design from your x10 that’s ported, and I can’t imagine that makes it easier to integrate the two. 

Gotta tell ya, to me another x10 makes a lot more sense on every level except looks.  Then again, given you may be looking for some added depth I think an even better (and cheaper) option might be an SVS PB1000 Pro.  Like your x10 it’s a ported design, but the 1000 would get you down to 19Hz (-3dB) and costs only $599.  Plus, and this is a biggie, SVS offers a generous and true risk-free trial period that includes shipping both ways, and they have excellent customer service and would probably be a big help in integrating your subs.  Either way, just adding a second sub is an excellent idea, and that alone is going to yield huge benefits to the quality of bass you’re getting.  Ok, that’s all I got.  Hope it helps, and best of luck. 

The advice I've gotten from various informed folks has been: second sub should match first one; more than 2, mix and match.

I agree with soix. Scratch the SF sub idea. But yes, add another sub by all means. I'm running three SVS (2 SB-2000 and a SB-3000 in the audio room in asymmetric locations with great results and would like a fourth. Paradigm makes good stuff; not sure how their subs stack up bang for the dollar with the surge of great inexpensive mfrs now, SVS, Rhythmyk, HSU, etc...   Idle curiosity, which SF model? I do like the sound generally.

What is your goal with the addition of another sub? Listening to 2 channel music on a dedicated 2 channel stereo, or both, home theater and music listening through an AV processor? If it’s 2 channel, whatever sub you decide to acquire (makes good sense to use same, however, not a show stopper…check out a pair of SVS Micro 3000s for a little added punch in the lows while saving space), you should measure the in room response to see what settings have an effect at the listening position. You will get the crawl, low crawl, hang em high, recommendations, but why? Use technology to see on a display as to how the sub settings can be smoothed out by changing certain parameters to get an ideal and smooth curve.


More subs allows you to balance those bass room interactions to a certain degree and get away with smaller subs to boot. You should still use bass absorption judiciously if required to further help room issues, in particular smalle rooms. Smaller rooms are way more complicated than larger rooms, so multiple subs aids a lot in smoothing out bass modes. Larger rooms are more forgiving because, well, they allow the lower frequency to travel farther thus reducing the amount of bass frequency propagation, although their is still some and you need to again measure. REW makes a great application to measure your room.



For home theater and fire and forget use, just use the built in room measuring equipment built into your processor if so equipped. You may still not like it’s results.
The reason I suggested the SVS Micro 3000 is that if all you are looking for is some bass assist, and a means to control the sub, these little powerhouses are ample enough, while being subtle in size to add that extra flair to bass without messing up the stereo image if used properly. They are equivalent to nearly 12” woofers with their dual 8” size. I may or may not be testing a pair in my very large room with very large speakers:)