Your experience of moving to two subs


Hi all, I have a 2.1 system with the sub sounding best in the center between the loudspeakers. My speakers have substantial, deep, and detailed bass for their size and with the SS amp I’ve chosen. Thus, the sub’s optimal crossover setting is only at about 28hz. I have plenty of bass amplitude going on -- don’t need "more" bass.

I’m wondering about soundstage effects of having two subs on the outsides of my speakers, though. Having my sub in the center does result in some apparent compression of the low frequencies towards the low-center area. The L and R channels from my preamp are combined at my sub. I know some people may disagree and think that the source of frequencies below 60hz can’t be located by human hearing, but my experience tells me differently.

Does anyone have an opinion on the benefits of 2 subs vs only 1 when there’s no need for more bass oompf?

128x128gladmo

It pressurizes the room more evenly and helps avoid or minimize in-room bass anomalies.  Plus, each sub doesn’t need to work as hard to produce the same bass.  I don’t know anyone here who prefers one sub compared to two, so take that for what it’s worth.  Best of luck. 

The oomph is not the goal for me, either. The goal is evenness, tightness, naturalness. It's like having a room with two vents for heating/cooling rather than one. It is about distribution of waves, in either case.

Guessing about subs is an infinite project. I suggest a umik and REW and some time spent measuring.

If your subs have adjustable phase, like my Rythmiks, that will help a lot. Sometimes subs need to interact in certain ways to create evenness. Adjustable phase makes that much easier. 

@hilde45  Is 100% correct.

"The oomph is not the goal ...... The goal is evenness, tightness, naturalness."

My findings indicate that two subs are better than one and four subs are better than two. 

 

According to acoustics and psychoacoustics researcher Earl Geddes, the in-room bass smoothness increases in proportion to the number of independent bass sources. So two subs can theoretically be twice as smooth in-room as one sub; four subs can theoretically be twice as smooth as two, and so on. "Independent" in this context means that the subwoofer locations are acoustically completely and significantly dissimilar, and in practice that just about never actually happens; for instance even if both subwoofers are placed asymmetrically with respect to the walls, both of them are probably still on the floor, thus they are both the same distance from the floor and ceiling.

That being said, imo two subs intelligently distributed will make a very much worthwhile improvement in in-room smoothness versus only having one sub. Ime a steep-slope low-pass filter (like 4th order) can be very helpful for rapidly rolling off the top end of any subs which are positioned well away from the main speakers.

And "smoother" bass = "faster" bass, subjectively as well as literally, because it is the in-room bass peaks which take longer to decay into inaudibility and which therefore muddy the bass response.

Improvements in smoothness in the bass region pay disproportionately large dividends. This is because our ears have a heightened sensitivity to changes in SPL in the bass region, which is shown by the way equal-loudness curves bunch up south of 100 Hz. A 5 dB peak in the 40 Hz region can be comparable in perceived loudness to a 10 dB peak at 1 kHz!

The improvement in bass smoothness tends to extend throughout the room, which makes equalization more likely to be an improvement over a large listening area. With just one sub, equalization tends to fix problems in one location at the expense of making things worse elsewhere. So two (or more) subs intelligently distributed have the added benefit of making equalization beneficial across a larger area.

Duke (manufacturer of a four-subwoofer system)