Thanks for the reply again GM,

fyi I opened up a separate thread on the four 416'b woofers I sent off to GPA to be remag / reconed:
Altec 416-8b woofers

Do to the above I'm kind of committed to using the 416-b woofers. It isn't imperative but after the recones I've quite a bit invested in them now.

Another snag I've realized is with a tall dual woofer MLTL it would probably be to tall to mount a 511 horn on top of the cabinet. (It'ed be up there aiming down) There isn't any way I can see to easily put the horn inside in a MLTL box without it still being high.

I could keep my subs and change my plans to a MTM design which could be made sealed since the subs would handle the lows. For sure that design would be easier. If I did that I would probably like to roll off the 416's a little which would help protect those magnets from becoming discharged again.

Or - I could ditch the subs and make the MLTL cabinets with the 416's horizontal rather than vertical. Cabinets would need to be about 40 inches wide but then not need to be so tall. 511's could be mounted on top that way. Woofers side by side wouldn't look as nice visually.

So much to think about!

Yes if I do get rid of my current subwoofers I would have two corners and could go with 40 inches wide cabinets. Depth wise I should probably limit to 24 inches max due to some furniture on the left might get in the way.

My room is fairly narrow (guessing maybe 16 feet wide) but very long because the dining room and kitchen are back behind the living room (no walls in between) Sofa is probably about 15 feet from the wall so would be about 12 feet back from the speakers. Ceiling is high and vaulted which does help my room a lot. Currently I have several bass traps and a bunch of acoustic panels I bought and put up. I think those don't really do a lot for lows but help a bit in the mids/highs.

I've got a Dayton omnimic which I've used for other designs and my room isn't to bad. I get good gain at the lowest frequencies which helps. I do have a slight null at 60-70 hz right at the listening sofa but I never considered that a very big issue.

Mark