fast_eddie_72 Posted March 31, 2015 Report Share Posted March 31, 2015 Hey All,I restored a pair of AR3as for a friend a few months ago. Well, he's had a bit of misfortune and one of the woofers isn't working well. I told him to ship it to me and we'd figure it out. We also ordered a recone kit which is here. When I got the woofer, I was a little surprised. It looks fine. Cone moves freely with no scratching or other indication of damage. I get about 2.5 ohms which is consistent with my spare AR9 woofer. But when I hook it up, er, yeah. It's not good. It makes sound, but not good sound. I just can't figure out what's actually wrong with it. Whatever it is, a recone should fix it, but I hate to tear it all the way down without knowing why. I expected to feel some resistance from a deformed voice coil, or an open coil. Sorry for the vague question. Just wanted to run that by you guys before I tear this woofer apart. Thanks,Ed Link to comment Share on other sites More sharing options...
DavidR Posted March 31, 2015 Report Share Posted March 31, 2015 Voice coil rub perhaps.Did you center the vc when installing the new surrounds? Link to comment Share on other sites More sharing options...
fast_eddie_72 Posted March 31, 2015 Author Report Share Posted March 31, 2015 Voice coil rub perhaps.Did you center the vc when installing the new surrounds?I did, and it's been in service for a few months, working great. But I guess it's worth pulling up the surround from the outside and testing a bit. Link to comment Share on other sites More sharing options...
fast_eddie_72 Posted March 31, 2015 Author Report Share Posted March 31, 2015 I should add the description of the failure. I was told he was listening to some music at pretty high volume using Pandora. When the next song came up it had a lot of low frequency stuff and things got to sounding bad in a hurry. He rushed to get the volume down, but the damage had been done. It was being driven by an Adcom GFA 555, so a good bit of power on tap. I'd assumed the voice coil bottomed out and deformed it. And that's still my working theory. I just thought I'd be able to feel it. The output is low and distorted. Link to comment Share on other sites More sharing options...
owlsplace Posted March 31, 2015 Report Share Posted March 31, 2015 Tear it down... love to see some photos of that one Link to comment Share on other sites More sharing options...
fast_eddie_72 Posted April 1, 2015 Author Report Share Posted April 1, 2015 Well, I took it apart. This is my first re-cone and it was really weird cutting through the foam I had installed, then cutting the cone! But I found the problem. Wow. Never seen anything like it. The voice coil is torn in two. The bottom half was well wedged in the gap. Had to give it a pretty fair pull to get it out. But I feel better at least seeing a clear problem. No question I can fix it. Link to comment Share on other sites More sharing options...
fast_eddie_72 Posted April 1, 2015 Author Report Share Posted April 1, 2015 So, I think I was right with my diagnosis. It bottomed out hard. So hard the deformed bottom of the voice coil got wedged into the gap. Then as the top part of the coil tried to move back up, they parted ways. I have to wonder if there was some damage there to begin with. It seems like it would take a lot of force to rip the coil into two parts. I would have expected it to just kind of lock the woofer in place. But now I understand why I couldn't feel the damage. The damaged part wasn't moving when I worked the cone by hand. Link to comment Share on other sites More sharing options...
DavidR Posted April 1, 2015 Report Share Posted April 1, 2015 Wow-za Link to comment Share on other sites More sharing options...
owlsplace Posted April 1, 2015 Report Share Posted April 1, 2015 Nice photos. Have to be nice to your senior AR speakers! RoyC mentioned problems with glue fail on the voice coils recently. Link to comment Share on other sites More sharing options...
Carlspeak Posted April 1, 2015 Report Share Posted April 1, 2015 I've seen a few of these in my time. The OP's is a particularly severe example. The AR3a voice coil former is perforated with holes just above the windings area. The holes are in the 1/8th to 3/16th's dia. range and are evenly distributed around the entire periphery at one level. The idea is the holes allow air to excape during the stroking of the woofer and then vent thru the spider forming a cooling mechanism since the pole piece isn't vented and the dust cap is not porous. If you look closely at the pictures, you will see some of the partial holes because it's the exact area that collapsed when the bottom of the voice coil slammed against the back pole plate. RIP mr. woofer. Recone kits are available. I've tried a few, but they don't match up with original specs very well. You are better off getting a replacement OEM off the bay if you want duplicate performance. Link to comment Share on other sites More sharing options...
stupidhead Posted April 1, 2015 Report Share Posted April 1, 2015 Glad to hear you now know the problem. Curiously I was going to suggest something like what recently happened to mine in this threadhttp://www.classicspeakerpages.net/IP.Board/index.php?showtopic=8332#entry101743and in fact while it looks similar, yours has self destructed!Nice pics btw and thanx for the post. Link to comment Share on other sites More sharing options...
Carlspeak Posted April 1, 2015 Report Share Posted April 1, 2015 Glad to hear you now know the problem. Curiously I was going to suggest something like what recently happened to mine in this threadhttp://www.classicspeakerpages.net/IP.Board/index.php?showtopic=8332#entry101743and in fact while it looks similar, yours has self destructed!Nice pics btw and thanx for the post.The voice coil former at your link doesn't have many holes. When I've seen collapsed formers, there wre many more holes which created a swiss cheese pattern and a weak area between each hole. Link to comment Share on other sites More sharing options...
RoyC Posted April 1, 2015 Report Share Posted April 1, 2015 The voice coil former at your link doesn't have many holes. When I've seen collapsed formers, there wre many more holes which created a swiss cheese pattern and a weak area between each hole.Hi Carl,The damaged voice coil shown in stupidhead's photo is of a 10 inch woofer and is smaller.I agree with you about the re-cone kit. The weak spot is the thin, light replacement cone. I try to salvage the old cone and just use a new spider and voice coil whenever possible.Roy Link to comment Share on other sites More sharing options...
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