The idea in this post is unorthodox, and is an adaptation of something I read in a paper written by David Griesinger, inventor of the Lexicon processor, many years ago.
My understanding is that the brain interprets low frequency phase differences at the left and right ear as hall ambience. To effectively present this phase differential to the left and right ears, we'd position the left and right subs approximately to the left and right of the listening area, rather than in the front of the room near the main speakers. If we're using multiple subs, this implies that we'd use an even number of subs, and perhaps spread them around somewhat (for the sake of modal smoothing) but they would be divided into two distinct sets: "Left-hand-ish side of the room" and "right-hand-ish side of the room".
It is also my understanding that low-frequency left/right phase differences are more likely to be present in live recordings, and more likely among classical recordings than other genres. Which implies that the number of recordings which benefit from stereo subwoofers (as opposed to the same number of mono subwoofers in the same locations) is fairly small.
In my experience the benefits of a left/right phase differential (and therefore the accompanying sense of envelopment) can be extended to lesser recordings by placing the left-side sub(s) approximately 90 degrees out-of-phase relative to the right-side sub(s). This phase relationship is called "phase quadrature", as it is one-quarter of a full 360-degree cycle. Thus we are in effect "synthesizing" a low-frequency phase difference at the left and right ears, from the typically-mono-summed low frequency energy on the recording. So we are using information on the recording, but presenting it in an arguably more psychoacoustically beneficial manner. The intention is to make the suspension of disbelief a little bit easier by enhancing the sense of being immersed in a larger acoustic space. (Imo whether or not that "larger acoustic space" perceptually bears an approximate resemblance to the recording venue also depends on what's happening further up the spectrum).
I have not found this phase quadrature technique to noticeably degrade the sense of envelopment in those live recordings which may already have hall ambience encoded as stereo bass, but it theoretically could, in which case dialing out the 90 degrees of phase differential might make sense for those recordings.
Arguably a beneficial side-effect of this phase quadrature technique is increased de-correlation of the low frequency energy, which helps smoothe the in-room frequency response.
I'm only aware of one professional review in which the reviewer tried the stereo + phase-quadrature technique, and that was when Robert E. Greene of The Absolute Sound reviewed my little multi-sub system in 2015. (If you take a look, see in particular the section entitled "The Spatial Effect".) The general idea can of course be implemented more effectively using much larger and more capable subwoofers... Funks and Seaton Submersives and Gensis SuperSubs and suchnot.
Anyway it was suggested to me that I post about this idea in the subwoofer forum, and I couldn't find an older thread it obviously dovetailed into, and didn't want to hijack the ongoing Genesis SuperSub thread.
My understanding is that the brain interprets low frequency phase differences at the left and right ear as hall ambience. To effectively present this phase differential to the left and right ears, we'd position the left and right subs approximately to the left and right of the listening area, rather than in the front of the room near the main speakers. If we're using multiple subs, this implies that we'd use an even number of subs, and perhaps spread them around somewhat (for the sake of modal smoothing) but they would be divided into two distinct sets: "Left-hand-ish side of the room" and "right-hand-ish side of the room".
It is also my understanding that low-frequency left/right phase differences are more likely to be present in live recordings, and more likely among classical recordings than other genres. Which implies that the number of recordings which benefit from stereo subwoofers (as opposed to the same number of mono subwoofers in the same locations) is fairly small.
In my experience the benefits of a left/right phase differential (and therefore the accompanying sense of envelopment) can be extended to lesser recordings by placing the left-side sub(s) approximately 90 degrees out-of-phase relative to the right-side sub(s). This phase relationship is called "phase quadrature", as it is one-quarter of a full 360-degree cycle. Thus we are in effect "synthesizing" a low-frequency phase difference at the left and right ears, from the typically-mono-summed low frequency energy on the recording. So we are using information on the recording, but presenting it in an arguably more psychoacoustically beneficial manner. The intention is to make the suspension of disbelief a little bit easier by enhancing the sense of being immersed in a larger acoustic space. (Imo whether or not that "larger acoustic space" perceptually bears an approximate resemblance to the recording venue also depends on what's happening further up the spectrum).
I have not found this phase quadrature technique to noticeably degrade the sense of envelopment in those live recordings which may already have hall ambience encoded as stereo bass, but it theoretically could, in which case dialing out the 90 degrees of phase differential might make sense for those recordings.
Arguably a beneficial side-effect of this phase quadrature technique is increased de-correlation of the low frequency energy, which helps smoothe the in-room frequency response.
I'm only aware of one professional review in which the reviewer tried the stereo + phase-quadrature technique, and that was when Robert E. Greene of The Absolute Sound reviewed my little multi-sub system in 2015. (If you take a look, see in particular the section entitled "The Spatial Effect".) The general idea can of course be implemented more effectively using much larger and more capable subwoofers... Funks and Seaton Submersives and Gensis SuperSubs and suchnot.
Anyway it was suggested to me that I post about this idea in the subwoofer forum, and I couldn't find an older thread it obviously dovetailed into, and didn't want to hijack the ongoing Genesis SuperSub thread.
