Is One Subwoofer Really Not Appropriate For 2-Chnl

Hi Bryon, great post! I have a practical question. As I mentioned above, I don't have a lot of placement options for my sub. So, my sub is aimed directly at my seating position and sits about 4-5 inches behind the mains.

In addition, I summed the channels into mono for the sub, so I don't think I can reverse polarity as you suggested, or perhaps I still don't understand how the method works. Having said that, my sub has a built in phase adjustment capability which I adjust to achieve the loudest bass when playing music that puts out a lot of bass. The thought is that I am trying to reduce phase cancellation at the crossover point.

Anything else I can do to improve the bass with my sub?? Thanks.

Bifwynne - Glad my post was helpful to you. If you can manage it, it would be worth the experiment to move the sub roughly coplanar with the mains and see if it improves the system's transient response. It will be audible as better coherence and PRaT.

The fact that you sum the channels into a mono signal for the sub doesn't affect anything in the procedure I described in my last post. If your sub has a polarity switch, use it. If it doesn't, just reverse the positive and negative leads on your speaker wire for *both* of the mains. Then the mains and the sub will have opposite polarity, assuming that your sub doesn't invert polarity.

Adjusting the sub's phase can be helpful, but not nearly as helpful, IME, as time aligning the sub. As I mentioned in my last post, if the sub is behind the mains, the signal that needs to be delayed is *the mains*. Adjusting the sub's phase will do nothing for that. If you cannot digitally delay the mains, you can time align the system by placing the sub coplanar with the mains, or possibly a little in front of them (to compensate for the potential latency - i.e. delay - introduced by the sub itself).

To sum up, if you can do it, move the sub so that it's roughly coplanar with one of the mains, then follow the procedure in my last post. That should get you pretty close to time aligned. IME, the results of sub time alignment are dramatic, especially when the sub is "fast" enough to keep up with the mains.

Bryon

One can work fine. I use a 10" NHT sub with my NHT Classic 3 speakers and the sound is very detailed and smooth.

Bryon,

It's been decades since I did research in binaural processing, but I wondered why someone from a university in South Carolina would publish such an article in other than JASA. Some of the contentions about levels of neural processing of temporal information seem astonishing, so I wonder if peer review may have been a problem. I'm also skeptical about the use of non-standard equipment; it makes replication of results difficult. I'm skeptical about your arguments and your source of "scientific' support. As I said, though, I haven't followed psychoacoustic literature for decades.

04-20-11: Dbphd
I wondered why someone from a university in South Carolina would publish such an article in other than JASA. Some of the contentions about levels of neural processing of temporal information seem astonishing, so I wonder if peer review may have been a problem.

The link I provided to the paper by Milind Kunchur was published in the Journal of the European Acoustics Association, which is a peer-reviewed journal, according to this page on their website.

I'm skeptical about your arguments and your source of "scientific' support.

Whether Kunchur's science is valid, I cannot say. I am no expert on auditory perception, but even if the limit of human temporal resolution is twenty times higher than Kunchur claims, that would still place it at only 1ms, in which case placement differences of approximately a foot or more would result in potentially audible time misalignment.

What I can say is that, IME, differences in z-axis sub placement are audible down to about 4 inches. That would correspond to about 25µs.

Regarding the science, you are certainly entitled to your skepticism. Regarding my statements about subwoofer time alignment, I would humbly suggest that you experiment with it before concluding that they are incorrect.

Bryon