[IronLion]

I already have one Zu Minimethod and I'm considering getting a second one for stereo bass, but I've never had two subs before and am wondering if this could potentially overpower the room (I guess I could set the levels on each sub so that this doesn't happen though right?) or if two subs are easier or more difficult to setup than a single sub?  I thought I've read somewhere that two subs generally makes for more even bass response but I'm not sure if I remember that correctly, or if that would apply to a smallish (11' x 15') room.  Anybody who's using two subs and might be able to give me some insight into the pro's and cons of dual subs?

[warnerwh]

Good questions. Using two subs does increase the smoothness of the bass response. Positioning is very important.
A key to excellent bass is of course the subwoofer itself. Easily as important are bass traps. The best sub in the world can sound like dull mess in a bad acoustical environment.

Traps are commercially available as well as inexpensive and easy diy projects.

Don't worry about overpowering the room with bass because like you said you can adjust levels. My room is only 12x17. I have two sealed subs, each 7.5 cubic feet internally. This does account for the rear of the driver as well as bracing. These each use the Parts Express RS HiFi 15" driver. 

If I turn up the bass or adjust the crossover into the wrong region bass goes down hill. When adjusted properly it makes music much more enjoyable. Real bass is much more important than most people realize.  This crap of this speakers goes down to 35hz or whatever is crap imo. What kind of power does it have there?  There's a big difference between my subs who's F3 is 30hz and most any speaker that claims to play down to that area of frequencies.

Bottom line is two subs can be better than one. However I'd rather have one really good sub with little in the compromise department rather than two subs that were doing as much pretending as doing real bass work.

[Duke]

Hello Iron Lion,

Large room-induced peaks, or level set too high, are what cause an otherwise decent subwoofer to "overpower" a room.  Using two subwoofers instead of one is likely to improve the low frequency room interaction.

In my opinion two subs placed somewhat asymmetrically is a significant improvement over one sub, and assuming you don't set the levels too high are actually less likely to overpower a room. 

You see, each subwoofer location will have a distinct peak-and-dip pattern due to how it interacts with the room (listening position also plays a role, but we'll assume that your listening position doesn't change).  By using two subs placed asymmetrically, their peak-and-dip patterns will not overlap and the net result will be smoother bass than you could get from a single (unequalized) sub - and therefore you're less likely to get a room-induced response peak that overpowers the room.  And note that equalization only works for one listening area, and can make things worse in another area. 

You can read more about the concept of multiple subwoofers here:

http://www.harman.com/wp/pdf/multsubs.pdf   Author Todd Welti advocates four symmetrically-positioned subs, offering two suggested placement configurations. 

As mentioned my preference is for asymmetrical placement, and here is a brief study that compares asymmetrical placement to one of Welti's symmetrical configurations:  http://www.gedlee.com/downloads/sub%20study%20.pdf

I spent several years working on a subwoofer system intended to integrate well with dipole speakers, and the approach that proved by far most successful was a multisub system using four small subs.

If you'd like some specific (but non-critical) suggestions on placement of two subs, let me know the size of your room and which wall your main speakers are along.  Also, let me know what approximate frequency the lowpass filter on your sub will be set for, and what the slope of that filter is.

Thanks,

Duke

[flintstone]

If your going to use a higher X=over setting (80hz and above)...two subs are a must IMO. 70hz and below...one sub is fine as long as you have no setup restrictions.

I own several subs


Dave

[Bob Reynolds]

Along with the paper that Duke suggested on the Harman site, take a look at Dr. Toole's "Getting the Bass Right." The take home message is that it all depends on the room, placement and very precise measurements (he suggests 1/10 octave).