I've been following discussions about polarity in vintage JBL studio monitors and have been involved in discussions specifically about 4343s. Giskard sent me his opinion on correct wiring on these 4343s with the 3143 crossover. I found that I had not wired them in correct polarity and, after making the changes, found the imaging and sound stage to be vastly improved! I did reverse all wires at the drivers from JBL's original specs so these would be compatable with all my other systems, but I feel I've got these all working in phase now.
My immediate reaction is that these 4343s sound like silk. There is no harshness, yet there is plenty of low end, ample mids, and lots of top detail. And now, instruments seem to float from between these cabinets.
FYI JBL's spec:
2231 green to red terminal
2121 blk/wht to red terminal
2420 red/wht to red terminal
2405 gry/wht to red terminal
Thanks again to Giskard for his help with this.
Tom