I recently upgraded my 2As to TL status, and they sound awesome. There's a lengthy thread on it. Some said it couldn't be done while other said it could, but no one had done it and reported back other than myself. The Hi-Pass of the 2A is identical to the 2B with the exception of a 2.7 ohm resistor in series with the shunt coil. The 2.7 ohm resistor is used to balance the output of the stereo and dimensional woofers to the tweeter out put. The 2As needed it, the 2Bs did not due to the different woofers being used in the 2B.
I'm now looking at doing the same thing with the 1Bs. The layout of the Hi-Pass section is essentially identical to the 2As (same generation) up to the point where the circuit splits for the two tweeters. I'm thinking the 5.8uf Capacitor installed accross the resistor would have the same effect for the 1B as it does for the 2A. Everything down-stream would remain the same. Any thoughts on this would be appreciated.