What's Better: One Subwoofer or Two?

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Q If I have a budget of $1500 to buy a subwoofer, should I buy one great sub or two good $750 subs? They would be used equally for both movies and music. Also, how do you connect more than one subwoofer to a receiver? —Raphaël Rainville, Montréal QC, Canada    

A That depends on what kind of listening experience you’re looking for. A big sub with a 15-inch driver should easily deliver deep bass extension and powerful dynamics. On the other hand, with two (or more) subs—even ones with smaller drivers—you can expect smoother, better-defined bass over a wider range of listening positions in your room.

Why? Standing waves. The interaction of the subwoofer’s output with your listening room creates modes that boost bass at certain frequencies, and cancels it out at others. Adding a second sub will help to even out those response peaks and dips. Also, a single sub can usually be localized by ear—something that isn’t the case when using two or more subs.

A few years ago, Sound & Vision published a listening comparison entitled Subwoofers: 4, 2, or 1? that attempted to gauge the sonic differences when listening with one big sub and multiple smaller subs. The tests used the same material to evaluate a single unit with a 15-inch driver, two 12-inchers, and four 8-inchers. The result? The 15-incher delivered the most authoritative low end, but its pitch definition was left wanting compared with the smaller sub configurations. It also found that while the quartet of 8 inchers failed to deliver muscular bass, the 12-inch pair was nearly as impressive as the 15-inch sub on that front. This lead the tester, Brent Butterworth, to conclude: “Two 12-inch subs in the front corners of the room is a damn good compromise for lots of situations.”

So, if you’re looking for brute bass power and the lowest possible extension, go the 15-inch route. But a pair of good 12-inch subwoofers can get you close to the same experience—and also deliver better—balanced bass. Oh yeah—to connect them to a receiver, just use a Y-splitter cable adapter plugged in to the receiver’s subwoofer output.

BobHD1's picture

The size of the room was not discussed in your answer. Does it matter? I have a 12.5 X 16 room that I use for both music and home theater. Would two 12" subs be overwhelming for a room that size?

utopianemo's picture

It was mentioned, but I want to emphasize that the subs should match. It's REALLY hard to iron out the kinks that a setup with mismatched subs presents.

rhirschey's picture

I have never owned what I would consider a "monster" sub (one with a driver >= 15" and/or huge amounts of amp power), but I have been using dual SVSound SB12-NSD's for a couple years now, having them placed in opposite corners and independently EQ'd by Audyssey MultEQ XT32. This configuration, while it may lack the brute force of a 15" monster, has good detail and bass is smooth around the room...all assertions made above and backed by thorough audio research. As long as you properly level/EQ your sub(s), to me it is hard to believe you can overwhelm any reasonably-sized room with two subs. It's worse to not have enough power/headroom, and then when you need it your system is left without steam to fill your room with ample bass. In a room 12' by 16', I doubt you'd turn the amp past halfway on either sub if you're running duals. I have my dual subs running in a 17' by 20' family room that is entirely open to the rest of the house, yet I don't have the amps turned past halfway and can still reach THX reference level with no problems, even when watching/listening to some pretty insane stuff.

pw's picture

With 2 subs you will note an increase in stage detail, as if (music CD) the Bass player onstage moves across the stage the bass image moves from right to left..
I've noticed running 2 10" subs increases my understanding of known music (Led Zep, Doors) as Jimmy Page for example alternated bass tracks in a song. You miss this if you run only 1 subwoofer.

kgh015's picture

I'm curious what you mean by matched subs. Is it only recommended to have multiples of identical units? For example, I have a Definitive SuperCube Reference in a relatively large room (25'x30'). It performs beautifully for movies, but with some music I'd like a little tighter bass. I've toyed with the idea of augmenting it with an additional smaller unit. Would that not be recommended? What about a smaller SuperCube as a second?

StudioApt HT's picture

Fantastic duo. My living space / HT is 12x15. I have never turned them up to halfway; I leave them just below, as recommended by the SVS customer service-- which also, by the way, is outstanding. Running them with Anthem MRX-500, Paradigm Millenia One Surround, and an Oppo BDP-93.

raph1001's picture

Thank you for the clear explanation ! I guess I'll go with dual subs, since many readers also think it has more advantages. Like other readers, I was also thinking SVS, maybe with the new SB-2000. For a single sub, I was eyeing E-sub E110. I want fast sub with a lot of definition to match my Magnepan MG12 (with mathcing center and surround speakers). Let's go shopping !

TimmyS's picture

You will be laughing your head off if you compare the difference between a single sub and TWO subs. Much lower distortion and more even room response. Way better than a single sub!

Ovation123's picture

I just added a sub to my setup--SVS PB-2000. Was originally planning to replace my old sub (Boston Acoustics PV900--decent sub. There's a review of it here at Sound and Vision) and move the old sub upstairs to the living room. However, I decided to first try and make it work with the SVS. It took a lot of measuring and trying a few different placements, but eventually I was able to get a really good response curve (using the PV900 in a near field placement, away from walls to minimize boundary gains, and with a low level setting for the output volume). The SVS provides me with much greater low end extension than the PV900, while the combination of the two subs (with an Anti-mode 8033C taming a major peak at 22hz) eliminates a nasty, deep null at 43hz and smooth another, less pronounced trough at about 60hz. The use of REW (free room measuring software) was essential in getting the response curve in great shape.

Two is definitely better than one.

mnc's picture

In the review of the SVS PB-2000 it was mentioned that in his large room it didn't perform as well as his PC13-Ultra. I asked hoe TWO PB-2000s would compare (a more fair comparison price-wise) to a single PC13-Ultra. I never got a response.
I'm still wondering how these would compare. While output would improve using two PB-2000s compared to just one, would it match the single Ultra? What about the PEQ features on the higher-end models? What about any perceived difference in the QUALITY of the bass? The Ultra driver is FAR better than the 2000 driver.

David Vaughn's picture
Sorry I didn't see your comment in the other review (we don't get notifications). Anyway, two PB-2000s would probably be the better choice for the reasons mentioned above. While the low-end extension may not go as deep, it's a fair trade-off for a more even bass response. As for the build-in EQ...it depends on how much you like to tinker. The majority of people find that the EQ in their AVR works great.
mnc's picture

I realize that two subs can help with room modes BUT only if they are properly placed. What if you don't have flexibility placing two subs? Can't it possibly do more harm than good? For instance, if the only place is next to the front left and right speakers, would you still get a better response?

rhirschey's picture

MNC, from what I have read placing two subs along the front walls (at the quarter points) is actually preferred for many rooms. That would likely place them next to your FR/FL speakers as you state. I've had this configuration before and it worked well. Look at figure 1c in the link. While placement is very important, having an AVR with decent subwoofer EQ helps a LOT after you've placed them as optimally/reasonably as your room will allow. A recent article here on S&V interviewing multiple subwoofer manufacturers had agreement that placement in opposite corners for two subs is best when you have EQ at your disposal, as it will excite room nodes (filling in voids) and allow the EQ to tame those peaks down.


Jonasandezekiel's picture

Hi David. Do you mind commenting on a previous person's post regarding matching 2 subwoofers? I found his question to be a good one. Do you need 2 exact same subs, or will different sized drivers or even different brands be acceptable? I would have to use 2 different sized subs if I were to add a second one.

Jonasandezekiel's picture

Hi David. Do you mind commenting on a previous person's post regarding matching 2 subwoofers? I found his question to be a good one. Do you need 2 exact same subs, or will different sized drivers or even different brands be acceptable? I would have to use 2 different sized subs if I were to add a second one.

rhirschey's picture

The link I shared above touches on this question. I've read elsewhere also that you should really try and match the subs, but this paragraph hopefully provides good justification.

"Ideally you should use identical subwoofers for the best overall performance, but it is possible to mix and match subwoofer brands and types if you're willing to do the extra work. If using mismatched subs, bear in mind that systems with different low frequency cutoffs may well be in phase and additive over most of their band, but at or below system resonance may well be out of phase. This can put us in the position of having the sub with a higher cut-off frequency reducing overall system output below its cutoff frequency. This is why we usually recommend using identical subs all around."

Chimneysweep's picture

I use my system equally for music and home theatre.
If I use a sub for each L/R channel to enhance the bass on my stereo system do I need another for the LFE channel on 5.1 for movies?