I never said any of this would be practical. But that it's possible. Not that I would listen at reference level :
skers_54 said:
If the acoustic sources are not co-located in space with identical dispersion patterns, phase at the listening position is random.
The electrical signals will net a 6 dB increase (if in phase). Pans Law. The acoustical signals can net a 6 dB increase too. It doesn't necessarily matter where the speakers are in this case because we are talking about signals
well below the x-over point. If all the information is summed together with the LFE there is no reason to assume it wouldn't be in phase.
Every reflection off every surface in the room from every speaker contributes and a significant portion are not in phase. That's why you don't get an ideal 6 dB increase with non-colocated acoustic sources.
Let's assume the summed redirected bass
is in phase. Distributing that signal over multiple subs, you should have less overall cancellation. But the signal requirements....which is the crux of the matter for me is different from sub handling LFE vs handling LFE
and redirected bass. There can be no free lunch.
FYI, I believe one can still achieve a full co-located 6 dB output at low frequencies if the distance of both sources are within 1/4 wavelength of the frequency you are trying to reproduce but that's another subject for debate.
Sure the direct sound is in phase but the reflections that contribute the majority of the sound are not.
You may even have higher overall sound if those reflections combine constructively. But let's assume the room acoustics are close to ideal in a home theater set up. I mean, reference level isn't practical 98% of the time because 98% of systems simply can't handle reference level bass output at low distortion, but reference level is reference level...
Again, just because the electrical signal is in phase doesn't mean that's true of the acoustic signal. Different distances, different dispersion patterns, different proximity to boundaries and inherent room asymmetries all factor in reducing the ideal gain.
If summed together and sent to a capable enough sub, there shouldn't be cancellation (assuming the signals are in phase at 0 dB's) especially if distributing over multiple subs, which would be recommended. Again, let us assume room acoustics are close to ideal. Let's assume close to ideal circumstances since it's a given that most won't reproduce reference level cleanly....it's simply not practical in most cases.