Originally Posted by J_Palmer_Cass
Just as a follow up, the best sounding setup that I have tried consists of adding a single speaker HP filtered at 50 Hz and LP filtered around 160 Hz or so (upper limit of the external subwoofer amplifier LP). The subwoofer amplifier is connected to the R & L preamp outputs with no time delay. The "Geddes" speaker is located near the listening area, to the side and a bit to the rear. The overlap method is being used.
The speaker that is being used is a typical 2-way speaker that matches my other speakers. F-3 of 60 Hz, single 6 1/2" driver with tweeter. I had to change from a subwoofer to a smaller speaker due to sound quality and interference between the front bass and the "Geddes" deep in room subwoofer.
The trick is you just want to "fill in" a bit in the mid and upper bass with the "Geddes" speaker without creating too much deep bass that will mess up the front bass. The 60 Hz f-3 of the speaker plus the 50 Hz HP filter keeps the sub 50 Hz bass interference free with the use of the "Geddes" speaker. The sound levels used are not that high, but you can hear a difference in the mid and upper bass.
I am still evaluating the setup, but I don't think that my system has ever sounded better than it does right now!
I was considering acquiring an additional subwoofer or two, and trying the multi-sub approach. The ULF sub in the front R corner. The first additional wideband sub would go along the middle of the rear wall, and the 2nd one on the L side wall, as a starting point.
But this post got me thinking. I already have a speaker on the side wall, above the center line, that can reproduce down to 50 Hz. It's my Ls speaker. And I have another pair of them on the rear wall, which can be driven in tandem (if that helps them to act like a speaker at midwall ??). It may not be ideal, but it's free to use one, or all four of these speakers for bass distribution, so I figure why not give them a try.
To derive the signals to feed them, I happen to have an electronic crossover on hand--again--no cost to put into this trial. The overall bass management plan is in the figure. Just as with real subs, I can adjust the LP filter and gain from each speaker, and I can also adjust time delay and even the HP filter as well, and the slopes of the crossover filters from 1, 2 ,3, 4, or 5th order, if need be. The unit has 4 independent outputs, so each can be tailored differently.
The ULF sub is covering 20 Hz to 50 Hz, the main L/R get the sub's HP output above 50 Hz. The L/R signals feeding the 2-ch crossover are summed to mono so all 4 filtered outputs contain the same content mix, which is the bass from every channel (incl LFE) nominally covering 50-150 Hz.
My HT room is a few weeks away from completion, so I cannot try it yet, but will do so. If it doesn't work, I may have to obtain separate subs after all, but I thought I'd try the most practical solution first. Even if I go for real subs, I may keep the crossover in the plan, as it gives me more flexibility than normal sub controls. For illustration purposes, assume all the resistors are 10k.