FWIW, here are several comments.
You can switch to a thicker gauge string at the same tension to see if it deadens the string bed. Use this site: http://www.stringway-nl.com/en/TAonline/calc.php
Or you can just try replicating the String Bed Stiffness using the same string
(don't think this will work.) Or you can find a 100" that had a dense central pattern. Or you can change your technique. Or a combination of all the above.