First of all Wayne I want to say Thank You for your reply and your opinion. I will consider what you have to say with the highest regard. I wish also to convey that I am thrilled with these speakers, but we all know that they are far from perfection...if there is such a thing at any price...
And as a mechanical design and automotive engineer that has a very competitive nature...having designed and built racing engines for 30 years...opening up these boxes and replacing parts...going A to B...back to A...is a walk in the park...
But I know audio technology is obviously not my forte...such is why I am soliciting help from the finest audio site on the net...
I think Fluance is on to something with the basic design of this speaker...I held Gene's review of these speakers as gospel...such as why I bi-amp with the LFE...and Gene was on the mark...
And if I may quote Gene now on the upper frequency issue..."The 1” silk dome tweeter is ferrofluid cooled and features a neodymium magnet structure. Although it’s not vented with a heatsink, it appears to be encased in an aluminum frame to help cool the magnet. Typically these tweeters don’t offer a lot of low end extension (as far as tweeters go), since they lack a rear chamber, so that is why Fluance chose to employ a higher than usual crossover point (3,500Hz)."
So having great success on the low frequency issue and Gene's recommendation...I now seek the advice and great expertise of the very intelligent audio experts that frequent this forum that together we may create the Ultimate XL7F...