Originally Posted by andyc56
I'm not aware of any receiver that mixes the LFE with the mains in this way. There may be an oddball Emotiva pre-pro that does it.
I hope you're not getting the impression that I'm dissing Earl here. I haven't met him in person, but I like him from the online discussions I've had with him. He certainly knows a heck of a lot more about acoustics than I do. It's just that I agree with about 99 percent of what he says, not 100 percent.
BTW, there's an interesting discussion about some of these topics that you may not have read yet involving Earl, Todd Welti, myself, Derrick and a few others starting here
I do recall this thread. I lurked but stayed out, it bothered Earl and there was nothing new going on there. A similar thread exists on DIYAudio that I think was better overall. Earl felt that "cheap" was misunderstood in that thread, that people were suggesting that going and buying a bunch of crappy low quality subwoofers was better than one good subwoofer because of the improved smoothness and were ultimately missing the real point. The thread has been dead for like 2 years though right? Earl still occasionally replies on DiyAudio but I think his health has been so so, either the Shoulder surgery or who knows, so he rarely seems to post. I find I can only talk to him via direct email or phone, nothing else is consistent.
So what makes you think receivers don't act this way with regard to LFE? I actually never tried it, but I had no reason to suspect that he was wrong about his assertion, or that it was unique to his pioneer receiver. For example, I do know that if you remove the center channel from the speaker setup, it does then mix in equal parts the center image to the L and R speakers. I've done this before to raise the center image and sometimes prefer this, especially with a lot of surround music (my center, while identical to my L and R speakers, is below the L and R because my screen is a SI Black Diamond and not acoustically transparent). It would make sense that if you turn off the subwoofer from the speaker setup, that it would remix the LFE channel to the L&R.
So I'm curious know about the double bass and how different receivers work. When I talked to Onkyo directly, they told me (possibly wrongly) that Double bass means that all of the bass from all channels is fed to the subwoofer and to any other speaker set to large. In other words, if I had 7 identical speakers set to large and a subwoofer set to 120hz. That all mains that were active and the subwoofers would get the bass (It wasn't cross mixing bass from mains to other mains though), that there would be intentional overlap so to speak. Earl looked at this as increasing the LF sources. Now my understanding is that if the bass was, for instance, in the left speaker and no other, then the subwoofer and left would both produce that bass. In a non-double bass scenario, whatever the crossover was for the mains is what separated it. if the bass contained content from 20-100hz, and the crossover was set at 80hz for the mains, then the left speaker handles the portion of that content that is 80-100hz, while the subwoofer handles below 80hz (and the only overlap is just what you have with the filters not being brick walls). Earl had once pointed out that the majority of movies and music actually have mono bass and often, quite intentionally, the bass content of a dynamic movie seen is found in all channels, so when you do this double bass, all the speakers tend to operate at the same time for that content. If there was a loud explosion and the sound engineer put at least some of that explosion into the mains, then they would overlap the subwoofer in that overlap area, regardless of the subwoofers crossover point. This gives then the needed effect of multiple LF sources.
It is my understanding that double bass does not mix the LFE channel into the mains, the only way to do that, according to what Earl told me, is to turn off the subwoofer and then use external DSP for bass management. I have no idea if that is true, I assumed it was. I never tested and I never asked Onkyo. I don't have sufficient DSP to do that so I've never even tried. I've actually always been curious because one problem I do have is that my rooms have always been small enough that my Schroeder frequency falls pretty high and I have evidence of discrete modes above 100hz but below 200hz. Just the right frequency to need some PEQ help, but outside the range of my subwoofers. The mains need to be EQed too since my subs cutout at 120hz. In a perfect world, I'd really like to add more midbass modules that operate up to 200hz and with DSP for the mains and the midbass modules so I can eq the signal to both. For example, right now I have a glitch that is clearly minimum phase around 150hz, and Audyssey doesn't do anything for it for some reason. It's a noticeable bump in the response that is there regardless of subwoofers being on or off or how they are setup, its probably due to the mains being too close to the rear wall and the room's dimensions (it perfectly matches a mode so I think I'm just exciting that mode). I've used a computer to feed it a signal massaged by Dirac and Dirac does fix the problem and to me at least, it does sound a lot better. I just can't use that with movies.