Wayne,
I've seen your posts on other forums discussing Karlson cabinet/speaker systems. I know you would not get into them right now, but might be a future possibility. I have a pair of Karlson 15's and and a pair of 1958 Popular Mechanic's design in my posession. I have to get some data to Freddy I. on the the other forum, but since you have expressed interest in the "Karlson" design, maybe you could elaborate for us here in the Pi forum. I think there are quite a few who might use them with either Altec/JBL/Martinelli horns for top end.By the way, I love my Martinelli horns for "wide" dispersion, and the Edgarhorns for narrow "soundstage". One of these days I will have to bring a pair of 811B/511B horns back out and compare again. Someday, I just might put a finish on those 4 horns since they are running just the way I bought them.
TillE, I remember you when 3.5 watts was plenty, now you are power hungry with your "Ella". I wonder how long before you discover "push-pull/parallel" 6550's to really blow out the windows where you live :-)
Regards, Ron