ninohernes Posted December 15, 2003 Report Share Posted December 15, 2003 Why is the magnet on the AR-4x woofer like it is? How come it does not have the alnico ring magnet bolted structure like all of the other AR speakers of the time? I am assuming that cost was the reason. I was thinking of replacing the woofers in them with replacements from AB tech, but I have decided not to. Insted I am going to send them to Bill Miller and have him install new surrounds and reglue the lose spiders. I feel that they will sound better than the new replacements. Link to comment Share on other sites More sharing options...
tysontom Posted December 15, 2003 Report Share Posted December 15, 2003 >Why is the magnet on the AR-4x woofer like it is? How come it>does not have the alnico ring magnet bolted structure like all>of the other AR speakers of the time? I am assuming that cost>was the reason. I was thinking of replacing the woofers in>them with replacements from AB tech, but I have decided not>to. Insted I am going to send them to Bill Miller and have him>install new surrounds and reglue the lose spiders. I feel that>they will sound better than the new replacements.The AR-4 and AR-4x, as well as the early AR-6 and 4-bolt AR-2ax and AR-5 woofers, used the pole-piece magnet. It is an Alnico magnet, but it is part of the magnet structure, forming the center pole piece, with the iron around it. It probably concentrates more flux in the gap than the conventional ceramic magnets for a given magnet weight, but it was certainly enough for those woofers, given their paramaters. I think the flux density for the AR-4x woofer is approximately equal to the ring-magnet assembly used on the original AR-2 woofer. The AR-4x, as in the case of the 10-inch woofers, had a "Q" of about 1.2 vs. approximately .7 for the larger 12-inch systems. This means that the frequency response at resonance for the AR-4x is slightly rising (a dB or two), which is probably desirable. The damping, nevertheless, was sufficient to prevent "ringing" or "hangover." Granted, that woofer is not as pretty as the ring-magnet Alnico versions, but it worked equally well for the particular application.The newer ceramic-magnet 8-inch woofers -- and there were several versions of it -- have greater power-handling capability, but do not appear to be superior in performance to the original woofer. The ceramic versions also got a new cone and urethane-foam surround. In the case of your AR-4x woofer problem, unless the surround is torn, I would not necessarily replace it with a new surround. You might also be able to glue the spider assembly back on the basket yourself.--Tom Tyson Link to comment Share on other sites More sharing options...
ninohernes Posted December 15, 2003 Author Report Share Posted December 15, 2003 >You might also be able to glue the spider assembly>back on the basket yourself.>>--Tom Tyson>>I have never attempted any repair of this type before, I dont even know where to begin. Link to comment Share on other sites More sharing options...
ninohernes Posted December 16, 2003 Author Report Share Posted December 16, 2003 >The newer ceramic-magnet 8-inch woofers -- and there were>several versions of it -- have greater power-handling>capability, but do not appear to be superior in performance to>the original woofer. The ceramic versions also got a new cone>and urethane-foam surround. >--Tom Tyson>>I am going to stick with the original woofers. The need for greater power handling is not necessary in these speakers. They are for a second system, which is 50 watts per channel, of very clean power. Link to comment Share on other sites More sharing options...
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