Advice on replacing 12 in woofer in Martin Logan Monolith III's

Thanks for all the input.  I have reached out to ScanPeak  for more data on the Discovery 30/4558.  Also inbox the guy that had the SV12's for sale,  but haven't heard anything. Even though the post was a year ago, I think maybe he still has them.   I will be putting a sub with the setup,  so I don't need it to down real deep.  Question:  what would be the ideal  crossover point for the ELS  running at three-way?

Even though the post was a year ago

My friend contacted him only 3 mts ago, still had them.

Cheers George

The MMS of the 30W/4558T00 is the moving mass, it’s some 36g higher/heavier than the SV-12 which says to me it’s not going to be as good at 130hz and 1 octave above, fine for below 80hz but the Monolith panels won’t take to that low frequency too well.

Cheers George

That's good news!   Hopefully he will respond to my inbox.  Thanks for all your help George!

just ran curves on the SV12 in 3 cu ft sealed.... It'll be 3db down @ about 31 hz with a qtc of .79