Hmmm... I think I was wrong about the LFE content. I looked on my PC and could not find the paper I was thinking about, and wasted a while on the Dolby site looking for a section with technology white papers. It's probably there, somewhere, but I don't know where,,, I also read the S&V article you linked, thank you.
What I found in my search was the diagram for one of my AVR's bass management schemes (not the Pioneer, but I am not sure if it is for the Denon or Sony -- no name on the picture). I probably grabbed it when I was first researching bass management before getting my Pioneer and after learning of Pioneer's scheme. For that AVR, the LFE channel has a 110 Hz LPF (not 120 Hz, don't know why, but that is what the diagram says) before the usual 10 dB gain stage and then a summer for bass from the other channels. The bass from the other channels goes through a second LPF before the summer o the sub, and that is variable as set by the crossover frequency. I found one other diagram for another AVR with essentially the same scheme. In other words, bass from the other channels is rolled off by the user-controllable LPF before being applied to the sub, but the LFE channel goes straight through to the sub. The diagram I have that I think
is for my Pioneer shows LPF's for each channel, including LFE, and all the LPF outputs are summed to go to the sub. All the LPF's are in one box and all controlled by the same crossover setting. So, in this case any LFE content over the crossover is lost.
So effectively I can't prove my claim so must redact with apologies. What I have evidence of is two of my AVRs (Sony and Denon as my Yamaha is older and I don't have any details for it) appear to send the LFE channel to the sub using its own LPF. Pioneer's LFE filter is ganged with all the other channels and controlled by the same, global, crossover setting. Here's the bullet list:
- In one case, the LFE has its own LPF (not user-controllable). All the other channels are summed, then go through a separate (single) LPF before being summed with the LFE signal going to the subwoofer. (Each channel also has its own LPF; seems a little wacky but that's what it shows.) The LFE signal is independent of the channel crossover so nothing is lost.
- In the second case again the LFE has its own LPF (not user-controllable). Each channel has its own LPF filter and the output of all the individual channel LPFs are summed with the LFE signal to drive the subwoofer. Again no LFE content is lost.
- Pioneer's scheme places a LPF in each channel, including the LFE, but all the LPF corners are set by a single (user-defined) crossover frequency. Thus any LFE above the global LPF setting is lost.
So in the first two schemes all LFE bandwidth is sent to the sub irrespective of the (user) crossover setting. In the Pioneer, any LFE signal over the (global, user) crossover is lost. Signal frequencies above the LFE crossover are not sent to the mains in any figure I have (except those without a sub, natch, in which case LFE is sent to the L/R speakers). So you are correct AFAIK that LFE is not sent to the mains (unless there is no sub).
Thanks for keeping me honest! - Don