Single vs. Dual Subs

You may have a single, fixed listening position, but the sound that you are hearing is coming from the whole room.  And a single sub, no matter how well placed, will tackle all the acoustic anomalies that the room has.  

I have a small dedicated listening room with a single chair in it. I had a single REL sub and thought my setup sounded pretty darn good (Anthem STR, Merlin TSM’s), I decided to try adding a second subwoofer, the improvement was well worth the investment.

One sub can be fine with your head in a vice. It depends how important a smooth room is to you.

twoleftears

Grow another one?

It's all about nodes. With one sub in a room smaller than a wavelength no two locations are going to have the same pressure, i.e.bass response.

What do two subs add to the music presentation that a single dialed in sub is missing provided that single sub is dialed in perfectly for the listening position?

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You answered your own question. If ONE sub was dialed in perfectly, the second sub will add ZERO.

The first one is dialed in PERFECT. STOP!! :-)

Second who said the first sub can’t have 6 active drivers and 12 passive radiators, BUT all in the same SINGLE 50 cubic foot box. :-)

One box fits all in some cases.. At one time I built 500 lb enclosures that were 22 cubic feet. You only needs two in a 50 x 100 x 12 room.
2 18" 2 15" and 4 passive 15" radiators.. 500 watts was plenty..
BTW they were Bins not subs, they were CUT on purpose at 28 hz and below.. 28-80 hz. The room still had 4 72" Narrow baffle bass columns 80-280hz. 6 8" MB drivers per enclosure

It’s about pressure in a room for BASS. 60-80hz and below not so much. WRONG kind of pressure.. High sub pressure can wear you out.. I don’t like it when I have to open my mouth to EQ the pressure fast enough to get clarity in the mids...

I've built single driver slot loaded bass bins.. ONE would fill a hole two car unfinished garage to 110+ db.. with 200 watts MAX. Boom Boom in the room room.. Modified Jensen Imperial Subs.. I've seen them look like an upright pianos, they were so big..

When you see SUBs working well into the BASS region, that’s when it get messy and bloated..

Regards

The technical theory behind multiple subs stacks up and there’s a lot of support for it. The only caveat I can see is that to make the most of it you need to be pretty flexible about where those subs go, if they just go right behind the L/R speakers then it may be an imperceptible improvement. Also it’s worth remembering that your room is a 3d space so different height placements should be considered as well. Basically symmetry is most pleasing to the eye but probably the worst way to lay out your two subs. If you have the freedom to put them wherever you want then there’s a good chance you’ll hear the benefits.
You’ll also want to do a bit of research into how to systematically set them up either by ear or using a mic.