Two vs four subwoofers for music playback

Hello guys,

I currently have a pair of subwoofers for my 2 channel audio system and I enjoy them very much as they make a big difference in sound quality, mostly on body, presence/ambience and 3D image.

I'm thinking about buying an extra pair of subs to emulate a Swarm bass array and smooth out even more the room bass response and get even better dynamics, 3D and presence.

Has anyone had experienced a similar situation?

Has anyone done it?

Can you share your thoughts here? 

Is it worth the expense and the effort of voicing extra subs? 


I went from no subs to a Distributed Bass Array and I will never, ever go back.

My system was set up professionally. Meaning, I paid someone who knows what they're doing and he used acoustical software to dial everything in. There was no guessing where to place the subs or how to dial each one in.

Of course, you can do it yourself. I'm sure many have and there are instructions for doing so. So I'm not advocating you pay someone to do it. I just know my limitations and what I wanted.

As for the reasons four is better than two (and two better than one) there are different, technical resources you can look at. Check out and you'll find the theory behind it.

You're half-way there. Like I said, two is definitely better (IMO) than none, so you may be happy right there. But, if you go further so will your entire system and musical experience. 

In short, I am 100% behind the benefit and value of a DBA. That's a big "yes" it's worth the expense and effort of the "extra subs".

I went from two subs to three. I considered four, but in my case, in a dedicated room, I have full freedom of placement and also have measurement equipment to get them where overall frequency response (FR) is smoothest. So I thought I’d try three first, since we’re getting old and trying not to get a ton more STUFF. I like the result. I still might go to four someday.

The advantages of three over two are easy to hear and match what people say. First, smoother FR at the main listening position. Second, a greater sense of envelopment. Third, far smoother FR across space in the room. I can walk around the room while bass-heavy music is playing and not go from areas of little bass to areas of too much bass. The variation is much, much less.

Try to get all four subs the same. If not identical, than at least don’t mix ported and sealed subs.

I also highly recommend measuring (use REW or an OmniMic [simpler!]). You can then fine-tune location and phase relationships to get smoothest bass. It’s not an absolute necessity, but I for one like to have the objective measurement in hand as well as listening impressions, especially in the bass.

When I added three more subwoofers it absolutly negated my rooms nulls and modes. Since the subwoofers have extensive multi band multi parameter processing the ability to better match the main speakers full range presentation in the crossover region was not subtle.

I've since removed two of the subs which resulted in a mode in an unused corner of the room. With every rooms uniqueness this may not be as desirable.

Mike's is good advise. The ability to see how your room is handling the low frequency is very useful. Along with repositioning and some form of processing you may find a level of satisfaction before committing to more subs. Good luck with it.

I think woofer towers are the best way to handle low frequencies. There are many statement systems that use that configuration. I think the multiple drivers are as effective as multiple subs but with better imaging. 

The use of woofer towers -- essentially stacked woofers -- will produce more output, but their usefulness at evening frequency response is debatable. The utility of a distributed bass array (DBA) comes from the distribution of woofers across distances that are significant fractions of a LF wavelength. Then ideally, one woofer’s node will be another woofer’s peak, and the response will be smoothed. It’s a kind of averaging.

That doesn’t happen by stacking woofers. It does happen by putting them in different parts of the room. Now, in stacking, the multiple woofer heights can help spread out floor-bounce cancellations, which is useful, but I would expect much more value to come from woofers distributed across space. A very tall woofer tower, I guess, could give some of that effect.

Every room is different, of course, and some will benefit more than others from DBAs. Some lucky listeners have rooms with exactly the right combination of bass retention and loss so that little or no special action is needed to get even frequency response.

A very tall woofer tower, I guess, could give some of that effect.

Notice how I said woofer tower not subwoofer tower. The main benefit is they crossover higher and recreate the recorded room ambiance. That is lost by distributed arrays. Towers are my preferred set-up for that very reason. I've been running an Infinity RS-1B woofer system for many years. 

What do you have today? I suggest you put your system photos under your user ID. That will give us something to work with.

I have have owned 4 B&W 800 subwoofers, two for my home theater and two for my two channel audio. At some point I upgraded my speakers and got rid of my subs… a great move. Better coherency… overall the sound took a giant leap up. But, it depends. What is your system?

According to Earl Geddes, whose ideas the Swarm is based on, the in-room smoothness goes up as the number of independent bass sources goes up.  So four subs intelligently-distributed are theoretically twice as smooth as two (and "smooth bass" = "fast bass" because it is the in-room peaks which take longer to decay into inaudibility).  In practice the measured improvement is typically not quite as good as in theory, but is still significant.

A little bit of frequency response improvement in the bass region goes a long way, and this is because the ear is actually more sensitive to changes in SPL at low frequencies than higher up the spectrum.  If you eyeball a set of equal-loudness curves, you will see that they bunch up in the bass region.  So a 5 dB change in SPL at 40 Hz is subjectively comparable to a 10 dB change in SPL at 1 kHz!  This heightened sensitivity to SPLdifferences at low frequencies is one of the reasons why it often takes a long time and a lot of fine-tuning to "dial in" the ideal gain setting on a subwoofer amp.

Also, it is not necessary that all four subs be identical.  In fact in his own distributed multi-sub system, only one of Earl Geddes' subs extends all the way down. 


Swarm manufacturer

Duke >> Also, it is not necessary that all four subs be identical.  In fact in his own distributed multi-sub system, only one of Earl Geddes' subs extends all the way down.  <<

Thanks for that information, Duke! In my setup, only one of three goes to 15 Hz, and it seems to be enough. Since that was only one example, I hesitate to recommend such an approach to others. But now with Geddes, N = 2, much better!

Hi guys

Thanks for the answers.

I like very much the bass response I get from my current set up and room, but it took some work to get it.

I think that I can try adding just one more sub and experiment with different locations and orientacions before buying a pair.

I also have límited places to place them due to decor, so buying a pair is much riskier.


Adding 4 subs in a distributed bass array was the single biggest improvement in the overall sound of my system. Fixed most of the issues I had previously with small room acoustics and put a big smile on my face.

My cat loves it.


When using four subs, are they used in stereo mode or mono? I've always found 2 stereo subs sound more spacious than 1. 



At least one of your subs should be a Velodyne dd+ so you can dial in perfect bass response at your main listening position at all levels. Preferably a 15".  :-)

If 2 is good, 4 must be better. Hell,12 should be the gateway to enlightenment!!!!

@aldnorab - I have heard of their being used in either way (stereo or mono). In my system, I use the 3 in mono, because of equipment limitations. Also, it’s hard to run 3 of anything in stereo! I ran the 2 in stereo before that.

As to spaciousness, that’s an interesting question. I am not sure how much spaciousness in stereo subs is real (i.e., on the recording) and how much is caused by slight phase differences, which might create a sense of spaciousness. IMO, it’s one of those areas in audio where it’s difficult to know exactly what’s going on. If I had 4 identical subs, though, I think I’d try them in stereo. One reads that many modern recordings do have stereo bass, and it would be interesting to compare.

My main speakers already go to 20Hz. But due to a standing wave in the room, there was no bass in the listening position! I added a pair of Swarm subs and it took no fiddling (once I placed the two subs I've not had to move them at all nor mess with their wiring). I set up the subwoofer amp per Duke's instruction and they worked a treat. I can tune the sub amp on and off and the difference at the listening position is profound. Its worth noting that nearly everywhere else in the room there is bass without the subs. I amp limited by the room layout as to where the listening position is though. So this proved an elegant solution.