dbenn Posted May 26, 2016 Report Share Posted May 26, 2016 This is my first post and i am wondering if anyone can help with this? I bought a nice pair of AR3a's locally that needed refoaming. When I removed the grills I found that they had been refoamed before The glue had become very gooey and was difficult to remove. after several hours of scraping and cleaning they were finally ready for the foam. I have not glued the foam to the frame because I am concerned that these woofers might have had the fiber ring removed in the previous (sloppy) refoam job. Can anyone tell if these should have the fiber ring and if so where I could get them? Thanks in advance dbenn Link to comment Share on other sites More sharing options...
michiganpat Posted May 26, 2016 Report Share Posted May 26, 2016 looks like they should....I mistakenly removed mine, but was able to make a new pair with a jig and a band saw.....if you have access to a bench top scroll saw, it's pretty easy....to use the band saw I had to split them to cut the ID, and then super glue the joint back together.... Link to comment Share on other sites More sharing options...
dbenn Posted May 27, 2016 Author Report Share Posted May 27, 2016 Thanks michiganpat I haven access to a cad table any ideas on a source for material and the right thickness? Link to comment Share on other sites More sharing options...
ra.ra Posted May 27, 2016 Report Share Posted May 27, 2016 Hi dbenn, and welcome to this forum. I am no expert with the various 12" AR woofers, but if indeed the fiberboard rings need to be replaced, this readily available material should work fine - - it accepts tooling very well and is dimensionally stable at 1/8" thickness. When I looked at your first woofer pic that shows the fat damping ring on the cone, I thought maybe you had the earlier AR-3 cloth woofer that had had its original cloth surround replaced with foam. However, when I then saw the round magnet on the backside, that was confirmation that the woofer has always had foam surrounds (is that a 1970 or 1976 date?). Nonetheless, your exact woofer does not seem to appear in the AR-3a restoration manual (pages 27, 28) which is why it was initially perplexing. Link to comment Share on other sites More sharing options...
RoyC Posted May 27, 2016 Report Share Posted May 27, 2016 dben, Your woofers are "transitional woofers", which showed up around 1970 when AR began using the foam surround/ferrite magnet 12 inch woofer. It retained the foam damping ring on the cone from the alnico magnet woofer, but the cone itself was more like the later versions of the woofer...and there was NO masonite ring under the foam surround! As we can see from your photos, the first ferrite magnet had indentations. This cone was changed, but this version of the magnet remained well into 1971. I've re-foamed a number of these woofers, and they work fine. We were unaware of this woofer when the 3a restoration guide was written. Roy Link to comment Share on other sites More sharing options...
ra.ra Posted May 27, 2016 Report Share Posted May 27, 2016 Thx for the excellent clarifications, Roy - - this woofer seemed to be something of a hybrid version, exhibiting components from various iterations during - - as you've said - - a transitional period. Knowing why this woofer does not show up in the guide makes sense now, and since there has been a good deal of discussion lately about the spacer ring, it is a valuable lesson to know that not all 3a foam woofers included this added masonite ring. Link to comment Share on other sites More sharing options...
DavidDru Posted May 27, 2016 Report Share Posted May 27, 2016 Good clarification there. The damping ring threw me as well. With that ring there, how is the removal and replacement of the dustcap challenged for shimming? Has there been talk about an addendum to the manual that would contain a few key learned tidbits? Welcome to CSP dbenn! Nice speakers. Link to comment Share on other sites More sharing options...
RoyC Posted May 27, 2016 Report Share Posted May 27, 2016 1 hour ago, DavidDru said: Good clarification there. The damping ring threw me as well. With that ring there, how is the removal and replacement of the dustcap challenged for shimming? Has there been talk about an addendum to the manual that would contain a few key learned tidbits? Welcome to CSP dbenn! Nice speakers. Hi David, Dust cap removal and shimming are not any more difficult to do than with other iterations of the woofer. As noted by dbenn, the old glue was thick and sticky so cleaning this woofer for the new foam is not as easy. There's been no talk about an addendum. Roy Link to comment Share on other sites More sharing options...
dbenn Posted May 27, 2016 Author Report Share Posted May 27, 2016 Wow thanks for all the help! This forum is really a great resource. This is my third pair of 3a's I've restored using the guide and the first with foam surrounds. the photo's show the only markings on the speakers one having 197(?). I haven't decided whether to remove the dustcaps and shim or use the tone method any advice would be welcome. Link to comment Share on other sites More sharing options...
Rich W Posted May 27, 2016 Report Share Posted May 27, 2016 11 hours ago, RoyC said: dben, Your woofers are "transitional woofers", which showed up around 1970 when AR began using the foam surround/ferrite magnet 12 inch woofer. It retained the foam damping ring on the cone from the alnico magnet woofer, but the cone itself was more like the later versions of the woofer...and there was NO masonite ring under the foam surround! As we can see from your photos, the first ferrite magnet had indentations. This cone was changed, but this version of the magnet remained well into 1971. I've re-foamed a number of these woofers, and they work fine. We were unaware of this woofer when the 3a restoration guide was written. Roy Hello dben, Roy is absolutely correct . . . no masonite ring. My AR-3a's had the same rare transitional woofer. See my post from 2007: Also, check if your 3a's have a #7 woofer inductor. If so, it should be upgraded to the correct #9. Best Regards, Rich W Link to comment Share on other sites More sharing options...
RoyC Posted May 27, 2016 Report Share Posted May 27, 2016 9 hours ago, dbenn said: Wow thanks for all the help! This forum is really a great resource. This is my third pair of 3a's I've restored using the guide and the first with foam surrounds. the photo's show the only markings on the speakers one having 197(?). I haven't decided whether to remove the dustcaps and shim or use the tone method any advice would be welcome. All of the professional speaker repair people I know use shims (whenever possible). This method is especially advantageous for AR woofers with cones lower than the basket rim, as it allows you to manipulate the height of the cone during the gluing process. Roy Link to comment Share on other sites More sharing options...
owlsplace Posted May 28, 2016 Report Share Posted May 28, 2016 1 hour ago, RoyC said: All of the professional speaker repair people I know use shims (whenever possible). This method is especially advantageous for AR woofers with cones lower than the basket rim, as it allows you to manipulate the height of the cone during the gluing process. Roy I imagine some of those old very compliant AR 12-inch woofer spiders are sagging a little bit also. Shims are the only way to insure they are centered for the remainder of their lifespan. Roger Link to comment Share on other sites More sharing options...
RoyC Posted May 28, 2016 Report Share Posted May 28, 2016 2 hours ago, owlsplace said: I imagine some of those old very compliant AR 12-inch woofer spiders are sagging a little bit also. Shims are the only way to insure they are centered for the remainder of their lifespan. Roger Agreed, Roger...The tone will not center a voice coil unless everything is well balanced to begin with. Roy Link to comment Share on other sites More sharing options...
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