Enter the AR Super-Mod. I've done it with a pair of high quality Seas drivers and an all-new xover. Clearer, more open sound but maintaining the original laid-back voicing. Other alternates done for select customers include a Scanspeak tweeter and also a ribbon tweeter.
Of course, the dispersion characteristics of the original 3/4 inch dome can't be matched by anything available today, the Super-Mod is a tad better than having a poor performaing pair of classics sitting around collecting dust.
Thanks for reminding us of your 3a Super-Mod, Carl. I would love to hear it someday, and willing to bet it sounds quite good...easily meeting the "classic New England sound" criteria.
If we are truly talking about the "classic New England sound", we have to remember that many of the "classic" representatives were not equipped with the AR 3/4" dome at all. Some ARs had 1 1/8" dome tweeters, and some had cones in them. Many other brands had 1 inch domes, much like the Seas tweeter used in Carl's design. KLH cone tweeters were recessed behind perforated metal plates! I would argue that given the deeply recessed cabinet baffle/heavy cloth covered masonite grille design of the old ARs, as well as most other speakers of the day, the dispersion attributes of the AR 3/4" dome tweeter have been blown way out of proportion as it relates to the sound character being discussed here.
As primarily restoration (preservation?) hobbyists, we are always walking the line between total authenticity as a "restoration" goal (or neurosis), and the temptation to tweak performance and reliability. Obviously, there are extremes to both approaches that can be counterproductive to maintaining the original personality of the old speakers, for which this forum exists.
Zilch, you rascal...