Charles218 Posted November 22, 2013 Report Share Posted November 22, 2013 I recently purchased a 3A cabinet to replace one that has substantial damage. It arrived this week and I was surprised to see what appears to be a custom crossover in addition to the original AR crossover. So I wanted to post a couple of photos and get a few opinions and thoughts about just what this is. In the first photo you can see that the McGee crossover is mounted below the mid and tweeter. Photos two and three are closeups and give a little more detail.Just curious to know about this. Link to comment Share on other sites More sharing options...
ligs Posted November 22, 2013 Report Share Posted November 22, 2013 How are the parts connected to the drivers? I see the typical 3 air coils used in AR3a in the lower part of picture1. However, the two iron cored inductors and two 80uf capacitors are not part of the AR3a crossover. BTW, many wires are cut so they are not connected to anything? Link to comment Share on other sites More sharing options...
Charles218 Posted November 25, 2013 Author Report Share Posted November 25, 2013 I've been away for a couple of days, just getting back to this thread.I've added two new photos with this post, and as you can see from the first photo, the components and wiring are rather confusing, the pots are laying loose in the cabinet, the large dual capacitor is also loose and flopping around in there. The two pairs of wires labeled #1 & #2, in the second photo, are routed out of the cabinet through the openings where the pots should be. It appears that the other two pairs of wires, marked "To Woofer" were connected to the woofer, though that is only an assumption. None of the wires that go to/from the board marked McKee are directly attached to the original AR crossover components.I hope this gives a better idea of what I have here. Link to comment Share on other sites More sharing options...
Charles218 Posted November 25, 2013 Author Report Share Posted November 25, 2013 Darn, I forgot this photo with the labels! Link to comment Share on other sites More sharing options...
RoyC Posted November 25, 2013 Report Share Posted November 25, 2013 I wanted to post a couple of photos and get a few opinions and thoughts about just what this is.Just curious to know about this.Charles,It looks to me like someone attempted to convert the cabinet into a "subwoofer" by disconnecting the original crossover, mid, and tweeter, and installing a new crossover for just the woofer.Fortunately the original inductors remain, so it should not be very difficult to get everything back in proper working order.Roy Link to comment Share on other sites More sharing options...
Carlspeak Posted November 25, 2013 Report Share Posted November 25, 2013 The two 80 uF caps appear to be in series. However, that wouldn't make sense since when caps are wired in series C=C/N. So, two caps of the same value would be redundant. If they are somehow in parallel, then their sum would be just 10 uF higher than a st'd 3a coil. Perhaps the two coils and two caps are indeed a subwoofer circuit with a LP knee somewhat different than the 3a 525 hz. Link to comment Share on other sites More sharing options...
ligs Posted November 25, 2013 Report Share Posted November 25, 2013 Charles,It looks to me like someone attempted to convert the cabinet into a "subwoofer" by disconnecting the original crossover, mid, and tweeter, and installing a new crossover for just the woofer.Fortunately the original inductors remain, so it should not be very difficult to get everything back in proper working order.RoyYou seem to make sense. This could be a 24db/oct low pass with two cascaded sections of LC. Typically iron cored inductors would have much higher inductance than air-cored inductors.. My guess that each of the iron-cored inductor would have inductance larger than the typical AR3a woofer air-cored inductor which has value between 2.6 and 2.8mH. Link to comment Share on other sites More sharing options...
RoyC Posted November 25, 2013 Report Share Posted November 25, 2013 You seem to make sense. This could be a 24db/oct low pass with two cascaded sections of LC. Typically iron cored inductors would have much higher inductance than air-cored inductors.. My guess that each of the iron-cored inductor would have inductance larger than the typical AR3a woofer air-cored inductor which has value between 2.6 and 2.8mH. Agreed, it has to be something like that...Actually the AR-3a woofer inductor value is 1.88mhm (#7) for the cloth surround woofer, and 2.85mh (#9) for the later version with the foam surround and ceramic magnet.Roy Link to comment Share on other sites More sharing options...
Charles218 Posted November 26, 2013 Author Report Share Posted November 26, 2013 Thanks for the info, it really is a strange looking setup and I didn't have a clue what was going on. It will soon be converted back to a stock 3A cabinet. Link to comment Share on other sites More sharing options...
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