No, man. This routing problem has been discussed before and it is not good. The best way is to avoid routing and using clean full range signal. Many people often say they can’t run their speakers full range (center, surround). I don’t understand why this is so difficult to do. All one needs to do is to find a powered subwoofer that has high level input and output level, or even better, internal Xover bypassing, that similar to this one , to do the passive bi-amping combo with their speaker. This method is also called "loudspeaker overlaping"

For example, if you want do a full range center. Just connect the full range center channel signal from the amplifier’s binding post to the LFM-1's High Level Inputs. Then, connect the high-level output terminals on the back of the LFM-1 back to your center channel speaker. Now, it is full range. This connection will let you run full range without using bass redirecting. You can also use this method for full range surround or any channel you feel like full range.

The best, buy yourself a an active Xover 24dB/octave Linkwitz-Riley active crossover from guitar center and connect it with your LFM-1 by flipping the switch on the back of LFM-1 to internal Xover bypassing mode for more precise fine tuning.

Before I upgraded into pure active Tri-amping, I use this connection for a while and it works great. The center channel would put out some serious bass like I experienced in cinema. No more hollow vocal; Just strong, well defined mid-bass.

The sub placement is also very easy. Just put it under your center channel speaker (many people put center channel above their TV) and between your front main.

No, man. The 24 DB Linkwitz-Riley crossover has a characteristic of absolutely flat amplitude response through out the passband with 24 dB/octave rolloff. Its low pass and high pass outputs are everywhere in phase with zero phase difference between drivers at crossover. That was what all about. Different crossover type has different characteristic. There’s also Butterworth, Bessel crossover. Linkwitz-Riley is pro standard.

I'm not sure why pre/pro designers would do this. The outboard analog active crossover units I've looked into have been 24/24 and with a rather flat sum of the outputs.

Well, yes, I totally agree - that's what I do. The problem is that most people don't want to mess with this stuff, so I would think the ICBM is a good compromise for them.

Personally, I think the whole bass management scheme is a load of junk that shouldn't have been foisted on the public. It was all done for economics so that small and cheap speakers that the wife would like could be made rather than full range jobs with real 12" or 15" woofers.

Dubbing theaters where movies are mixed do not use bass management.

Well, I have full-range mains (down to 32 Hz) and have been planning to do the hi-level config with "Large" L/R and "No Sub" to drive both subs in an 'envelopment' configuration. (Room is still in process.) That would eliminate re-direction problems on those channels (combining the LFE should not present a problem since there are no filters involved).

But I don't have full-range center and surrounds. If I set them to "Small" then the phase problem is back. If I set them to "Large" the bass content of those channels is lost.

Which are you suggesting?

teod and bb4tb:

See that's just it. I *do* understand why they use 12 db/octave for the LPF and 24 dB/octave for the HPF: because the slopes on either side of the crossover are identical: 24/80 = 12/40 (for example, for an 80 Hz crossover).

These are just words that aren't backed up by how the slopes add together. Others have stated it before too, but the slopes do not add up. Can you add some more info? (I think I saw once "flat amplitude response" maybe vs "flat energy response" or something.) ??

I actually do now also listen to SACD and DVD-A all large, sub on. (My "weakest" speakers still do -3 dB to 45 Hz. Mains are -3 dB to 30 Hz.) Music doesn't have much content below 40 Hz, and I personally feel you lose more with bad BM than by speakers that roll off too soon. But for movies, I do use digital BM and TA.

Yes, man. But I really don’t understand why most women hate to see large speakers in the living room. That is really unreasonable. A wife should enjoy audio as much as her husband does. That is a happy marriage. If that is a problem, I would rather not marry. I think stay single will give you more freedom. For example, I don’t have to worry about kids, wife, family expenses and whole bunch of troublesome issues I could imagine of that would later come up in the marriage. I could do whatever I want to do. No restriction at all by the wife and family. But, that is just my opinion. Maybe I am just too young. What do you think, man?

By the way, in cinema they don’t use bass management for movie soundtrack playback either. A very powerful stage LCR channel setup will beat any wimpy 5.1 or even 7.1 that is improperly setup.

My understanding of a –24db per octave L-R crossover is:

At an example crossover frequency of 80Hz, the low-pass section has started it’s roll-off below 80Hz. At 80Hz the signal is already –6db down. The high-pass section is complimentary to this. As the frequency rises, the slope upward crosses through 80Hz at –6db down and does not approach 0 db until higher than 80Hz. Since complimentary resistor-capacitor networks are used, and at the same rate of –24db per octave for both high-pass and low-pass, the phase shifts but remains coherent. With the same resistor-capacitor values chosen to halve the amplitude at 80Hz for both rising and falling frequencies, combining the two outputs for a test would show that at 80Hz, the two –6db levels sum to 0db, resulting in a close-to-flat response through the crossover point.

Maybe I need a better education on this?

24dB/octave Linkwitz/Riley crossovers are indeed amplitude flat through the crossover point. This can be proven by summing the two sections (lo pass and hi pass) through two equal value resistors and measuring the frequency response through the crossover region. It will be ruler flat. The phase also has to be zero degrees too since any other phase angle would introduce amplitude variations in the crossover region with the simple summed resistor network, or any active summing netork.

I think you should stick to giving advice about subjects you have experience in and know something about. Just my humble, married with a six month old son and never been happier in my life opinion.
Another result of those small, non-full range speakers foisted upon us unsuspecting consumers is that we can have multi-channel home theaters in reasonably sized spaces without having a multi-million dollar/year salary.