Two vs four subwoofers for music playback

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. 

Duke

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!