Sounds like it should be fun for Jerry to figure out the Professional III crossover. I prefer hard solder to edge connectors of old, I'm sure they were fine as KEF used them a lot, but the sure connection in my mind beats the convenience, even if you're going to have to label, then unsolder at the crossover - especially as its kinda difficult to get to the drivers' mounting unless you take off the baffle. OTOH, you might be looking to renew the wiring as well to drivers and input connector.
Thanks for the tip on the foam, I keep forgetting about other online resources. I'll check out the foam factory. As for diffraction issues, probably some truth to that although some have addressed that using felt/foam around the tweeters, a la LS3/5a, while others put triangular or square foam along the inner edges of the grill frames. I suppose the large foam grill would reduce diffraction too. I mean, look at that fairly deep aluminum edge frame that IMF used on most of their large speakers, cosmetically its nice (and mostly unique, only a few other speakers used it), but it certainly would add edge and step issues to the baffle, theoretically at least.
Was the previous owner using them much or have they been sitting for awhile? If sitting, the overall sound might open up a bit as the caps reform somewhat with applied voltage - OTOH, dried out electrolytics don't come back to complete capacity, and these are at least 30 years old.
Love to hear your continued impressions as you get more listening time.
