B&K and Martin Logan Theater i

Have you increased the center level on the fly?

Rynopr:
I too have the Laurier with the bridge. I'd been struggling with a similar problem. I have the ML Logos as my center with Martin Logan CLS's in the front and Aerius's in the rears. Movie dialogue sounded muddy and difficult to understand. I tried a different AV processor but nothing seemed to help.
My problem turned out to be echo waves that were peaking where the wall in back of me hit the ceiling. That wall is about 20 feet high and undamped without any sound treatments, bookcases etc.
I didn't figure the problem out until I stood on a stepladder and started clapping as loud as I could in front of the Logos at varying heights. Lo and behold I got terrible echoing and "ringing" at the wall/ceiling junction when I clapped at the height of the bridge but none when I clapped down at floor height. My problem was solved. Once I moved the Logos onto the floor I could suddenly understand all the movie dialogue I was missing. Later, for asthetic reasons, I may move the Logos back onto the Laurier bridge and invest in quarter round echo busters at the ceiling junction.
Try the clapping test and see if you detect echos at the wall/ceiling junction behind you. Either damp those with room treatments or move the center channel onto the floor.
I hope this might help.

First (and likely not most importantly however) those movies, I remember didn't have the best dialog mixes on DVD. I own SEVEN and do remember that.in
However, as being that many movies(if not most) offer somewhat of a "boxy center channel mix" (due to editting, dubbing, mixing, and remixing, etc), you can expect less than transparent quality comming from the center. That said, if your system balance, your level matching, your speaker placment set up, your overall calibration and frequency response and sub levels and acoustics are all off, you'll have a much COMPOUNDED PROBLEM with DIALOG INTELLIGIBILITY!!!!
MOST PEOPLE, even those using higher end-resolution speakers, get poor results because all the factors mentioned (compounded by POOR SET UP/bad balance and frequency response issues) above add up to too many sonic challenges thrown into the mix! It's WAY TOO EASY TO HAVE BASS TURNED UP TOO HIGH, and/or too BOOMY AND PEAKY, which will inevitably help DROWN OUT THE MIDRANGE AND TREBBLE!...believe it!
MOST PEOPLE have that "UP AND DOWN ON THE VOLUME" PROBLEM,such as you're experiencing! Loud passages have you "cranking down the volume", and soft passages with difficult dialog have you "pushing up the volume". THIS IS MAINLY A "SYSTEM BALANCE PROBLEM"! (the reason system tweaking, calibration, acoustics, flat frequency response and level matching are all critlcal!!!.)
Most people think you just buy expensive gear and it sounds wonderful!...not hardly. That's why you need people who know what they're doing for WORLD CLASS RESULTS...basically, it takes years.
Another reason "Theater speakers" are so effective for, well, home theater! They're made for pressence, dynamics, and dialog intelligibility and detail. They're not made for sounding "pretty and transparent" often!(not of critical importance for movie mixes in the end).
You can however fix much of your issues, and help difficult(yes a bit boxy) dialog problems from your center. Start by checking frequency response(speaker and seating placment factors), speaker levels and matching(between them), acoustics, etc(is your speaker to close to the ground, other reflective reinforcment, boundaries, etc?...also, is there a table or reflective surface between you and the speaker?...if up high, what's the ceiling like?...anything to break up relections up there?)
It's all a BALANCING ACT! Lots of factors influence the results. Get em right, and you'll not care about all the boxy mixing that is inherent in the center!(note: even at movie theaters the dialog is a bit boxy, due to mix).
All great systems/setup's offer very HIGH DIALOG INTELLIGEBILITY! After all, the center is critical for anchoring the movie, indeed! Start with one thing at a time.
Otherwise, your best bet is hiring a pro to get your money's worth out of your investment.
It's been proven a gillion times that you can spend money having a pro do it right, spend less of the gear, and you'll get infinitely better results most often even!
There's no replacment for experience.
Good luck
P.S.,...the $2500 Logan center is "beamy", (design nature) and you must aim it towards your ears!!!!. If not, comb-filtiering and "roll-off" will further kill your cause!!!!!