speaker dave Posted March 24, 2009 Report Share Posted March 24, 2009 Hi All,I've been replacing the surrounds on my AR2ax woofers. The MSound kits with the "JBL" surround seem like a perfect fit and the instructions are very clear.The odd thing and a question for the 2ax experts: One woofer is Alnico and the other is a square ferrite structure. Both are date coded in 73. I can't read the Alnico (other than the 73) but the Ferrite is 561/7346 which I assume means the 46th week of 1973. Visually the woofers are identical with cones, dustcaps and other details that are a clear match.It is possible that one is a service replacement, but since the dates are similar I wonder if I just have a pair of systems that straddle the transition? If AR felt these (ferrite structures) were perfect replacements they might have built mixed batches with the last of the Alnicos intermixed with the first of the ferrites.Any ideas?David Link to comment Share on other sites More sharing options...
Steve F Posted March 24, 2009 Report Share Posted March 24, 2009 I inherited a pair of 3a's from an older cousin in 2001. He had purchased them in the 1971-ish time frame or thereabouts.I was checking them out, and discovered that one woofer was a cloth-surround woofer, the other was a foam (rotted) ferrite magnet woofer. Both woofers were original to the speakers (never replaced), and so, yes, based on my experience it would seem that AR felt the two woofer types were close enough to mix as pairs during the transition.Steve F. Link to comment Share on other sites More sharing options...
speaker dave Posted March 24, 2009 Author Report Share Posted March 24, 2009 "one woofer was a cloth-surround woofer, the other was a foam (rotted) ferrite magnet woofer. "Steve F.Isn't that wild? They would even look different from the outside.As you well know, today we could never get away with that, appearance is so key. Hot melting the grilles on is the answer!David Link to comment Share on other sites More sharing options...
charger3834 Posted March 28, 2009 Report Share Posted March 28, 2009 Hi Dave,I have not been on this forum in a long while, but I saw this topic and I had to drop in. In late 1973 or early 1974, AR upgraded it's 10" woofer yet again. They changed out the Alnico magnet for the square ferrite magnet that you describe. I think you have a transitional pair. The new version had stronger midrange output or something that caused AR to add resistors to the 6.5 ohm CTS midrange. Eventually they dropped the resistors in favor of a 9 ohm version of that midrange. My questions for you Dave are:1. What are the serial numbers of the cabinets in question?2. Does your midrange on the speaker with the ferrite magnet have the resistors?Cheers,Brad Evans Link to comment Share on other sites More sharing options...
speaker dave Posted April 1, 2009 Author Report Share Posted April 1, 2009 Hi Dave,My questions for you Dave are:1. What are the serial numbers of the cabinets in question?2. Does your midrange on the speaker with the ferrite magnet have the resistors?Cheers,Brad EvansHi Brad,Thanks for the response.The serial numbers are AX242332 and AX242462, so they are 130 units apart. Both have an EIA code with 7347 which I take to mean built the same 47th week of 73. I assume they were bought as a pair (I got them used, not new, for my father around 1980). If speakers weren't pair matched (by veneer) then many companies or dealers wouldn't worry too much about sequential serial numbers. I don't think there were any extra resistors in the network for the mids. I don't have them open now but all I remember is the box capacitor (4 and 6uf) and the variable pots.By the way, I've been taking some response curves with an RTA and might have something to share with the group soon.Regards,David Link to comment Share on other sites More sharing options...
charger3834 Posted April 8, 2009 Report Share Posted April 8, 2009 Hi Brad,Thanks for the response.The serial numbers are AX242332 and AX242462, so they are 130 units apart. Both have an EIA code with 7347 which I take to mean built the same 47th week of 73. Correct I have 250734 with an EIA of 74 12. I assume they were bought as a pair (I got them used, not new, for my father around 1980). If speakers weren't pair matched (by veneer) then many companies or dealers wouldn't worry too much about sequential serial numbers. AR-2ax's were not sold as pairs! Close serial numbers are are always good of course.I don't think there were any extra resistors in the network for the mids. I don't have them open now but all I remember is the box capacitor (4 and 6uf) and the variable pots.I will bet you dinner that there is two 3 ohm sand cast resistors glued on the back of the midrange of the speaker with the ferrite magnet! Link to comment Share on other sites More sharing options...
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