Originally Posted by tjcinnamon
it would be a Y adapter from my LR pre-outs to a Y adapter with my LFE. The signal being sent would be LFE/Left-front/Right-front. This way I could get 45Hz to 160Hz. I don't want to run my LR crossovers at 40Hz. They can theoretically handle it but I'm not sure I'm into that. If I do keep my crossoers at 40 then I can run the MBM's through the LR pre-outs and then set up an LPF around 140Hz.
I know I'm kind of drive-by shooting to get an answer to your question. Forgive me.
Here is the response from my colleague who was involved in the discussion with the mixing engineer. He used the acronym "SSP" meaning surround sound processor in your AVR/AVC.
See what you can make of that for now. Forgive, but I don't have the time to dive in with you today.
"The short answer is that what he describes would not
be acoustic summing in the sense I was using the term, since he would be sending an electrical sum of the L/R main channels and LFE to subwoofers and MBMs.
Based on his description, I'm not entirely
sure what his goal is. It seems
that he is concerned about crossing his L/R mains at 45 Hz due to concerns over the output capability. If this is the case, the preferred solution is typically to raise the crossover frequency to something like 80 Hz. If this is undesirable for some reason, he can add another woofer cabinet to the L/R by using an external crossover. He would set the SSP crossover to 45 Hz, then run the L/R outputs into the external crossover which is set to 160 Hz. The high-pass from the external crossover would go the L/R main amplifiers, while the low-pass would go to the L/R MBM amplifiers. He doesn't mention the center; if it is the same type speaker as the L/R, something similar should be done to it. The center typically handles more power than the L/R.
LFE would be handled by the subwoofers, and the bandwidth on the top end (typically 80 or 120 Hz) would be set by the SSP (most SSPs allow the LFE low-pass to be adjusted independently of the mains crossovers).
We did this for a large dealer showroom where the dealer wanted a Triad THX-certified sound system. The Triad Platinum LCR would have easily handled the room, but was not THX. The Gold LCR was THX, but lacked the woofer power for the room size. To remedy this, we inserted a 10" Bronze subwoofer in the baffle underneath each Gold LCR with a crossover at 120 Hz. The main subwoofer crossover for the whole system remained at 80 Hz, and the LFE channel was low-passed at 80 Hz."