Sub and LFE settings on Surround Processor

My speakers are Magnepan 1.6 which are not known for LF response, but, to my surprise, actually do measure flat to about 40 Hz. Accordingly I started out with the SW crossover at 65 Hz. However, I now obtain better results at 90Hz. I conclude that, although the MG 1.6 can do it down to 40 Hz, they are working too hard at it. Moving the crossover frequency up to 90 Hz gets rid of a lot of diaphram flapping around which doubtless degrades fidelity at higher frequencies. What I am suggesting is that the crossover criteria can be how high your SW can go (with good sound) instead of how low your main speakers can go.
I suggest you experiment a bit.

Very good point Eldartford, speakers such as Magnepan, Apogee or other full range ribbon speakers do have deep bass responce, and do require huge force from amp which can degrade sound. My speakers are 9 driver/15inch active/15inch passive/12inch active/ 4ohm and 91db., they sound best rolled in full range in my case. Your suggestion to experiment both ways would be best.

I have Revel Studios which do have a fairly good bass response at the low end. My problem is that my system allows me to control the level of the LFE and Subs separately as well as the Hz level. This allows three potential adjustment for each profile. Eldartford's point that I should take it up to the highest potential level is good for a try, but actually I have been going in the other direction. My speakers do pretty good and my feeling is at least on music to use them to the point where they don't pick up the low end that the subs could handle. On movies I don't want to kill the mains when I have two subs to handle all the kaboom crash stuff.

Ken you should run your Revel mains full range for music. If you can control the slope of the roll off for the low frequencies [6db 12db 18db 24db] then you set the slope at the slowest setting provided. 6db being slower than 12db etc. Usually the slower the slope the lower the frequency setting should be placed, in your case 12db. I would place freq hz at 40 to 45hz. One issue that is in question and the hardest to measure and also to cure is accoustic phase relationships and wave launch of all the drivers. Wow. Ken remember I have an RTA. I believe you live not to far from me. You supply the beverages?

Tom what a reality. Bring the RTA I'll supply whatever. Moving the subs more to corners did cure the overload on movies.