I am a big fan of these awesome LF drivers and have some questions I hope can be answered. First, one of the first good buys I made in regards to vintage JBL was a pair of huge custom cabs with (2) 2231A's, (2)D216's , an LE85/HL87 and an 077 UHF per cab. One of the cabs had 2231's and the other 2205's with 2231A factory cones instead of the pleated surround stock ones. I inquired to a friend who said that this 2205A to 2231A conversion was not a problem. He then went on to say that the 136A is the same too but that for some reason, the LF response of his L300's was better than his 4333a's. I thought that the 2231A and the 136A's were identical as far as T/S parameters were concerned?. Could the LF response difference be in the crossovers?. Now, I have had some 2231A baskets with 2235H cones too. Are the T/S parameters the same for this combo, will a 2231A/2235H(cone) perform with the exact T/S parameters or is it just close? My questions are important because I am working on a project that will use one of the three depending on the answers I may get. Also, I was made aware the there are different "grades" of spiders (stiffness) and would appreciate any information as to the proper grade used in these drivers from the factory. I love the bass response with a Passive Radiator (I know, I know, it's just ME!) and would like to hear from anyone that has had or has, some Olympus SR8's or S7's. I realize that these speakers use a different LF driver but I would like to know how they perform in the LF region, hopefully, KILLER. I will thank you now for taking the time to answer these questions- THANK YOU!! -Steve G