I recommend you pose this question on the HiFi Haven forum, as many of the members are Altec afficionado's with strong DIY skills. It's a friendly, knowledgeable and helpful group.
ALTEC MAGNIFICENTS.....MODIFICATIONS
I have a very nice pair of these very large Altec speakers.....I am working on the cabinet at this time but would be interested in what , if anything owners are doing with the crossovers......At this time they have N-1500 crossovers.........Any first hand information would be very nice............My last speaker project wasn't so good, so I'm working on "REAL" speakers now......