Frzninvt Posted August 15, 2003 Share Posted August 15, 2003 I have schematics for the AK-2 & AK-3 the only differences that I can see is that the AK-2 has a 140uf cap in the woofer circuit as opposed to the twin 50uf's in the AK-3 so I ordered (2) Solen 100uf caps to replace the 140uf's in the AK-2. The only other difference is the 4mh coil in the midrange circuit on the AK-2 compared to the 5mh in the AK-3 so I ordered (2) 5mh coils with 18 gauge wire since I think that the 300W power handling is more than enough for the squawker. I see that the autoformer is slightly different but I think that is negligible. So my thoughts are that these mods will make my AK-2 an AK-3. Is it a big deal that I am using a single 100uf instead of the (2) 50uf's in the woofer circuit. Any thoughts or comments are welcome. Quote Link to comment Share on other sites More sharing options...
JohnA Posted August 15, 2003 Share Posted August 15, 2003 Looks fine to me. I believe you will also benefit from changing the woofer inductor to a 14 ga or larger Solen Perfect Lay, or Alpha-core, air-core inductor. Al K. tested the cheap OEM inductors and found the value changed at alarmingly low voltages. That indicates saturation. The air-core inductors won't do that, keeping the crossover point stable. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted August 21, 2003 Author Share Posted August 21, 2003 I got my caps and coils, the Solen caps were HUGE! The AK-2 schematic showed a single 140uf cap but in reality it is a pair of 70uf coupled together. I thought I had received/ordered the wrong cap until I removed the woofer access door and saw the size of the two 70uf Aerovox caps in there. I replaced the two Aerovox caps with the one large Solen cap. Now I see why John wanted me to replace that 4mh coil in there it is an old iron core type. I replaced the 4mh coil in the midrange circuit with the 5mh 18ga one I got. The mids do seem more clear in that speaker now, I don't notice much difference in the woofer but I am sure it is there. I need to do the other speaker yet. I think I will replace the 4mh in the woofer circuit as John recommended and might do the 13uf cap for the midrange as well. Where can I get Hovland caps? I ordered my stuff from Parts Express and did not see Hovland as an option. The inductors I got were not super special but I am certain they were an improvment over the originals. So I am on my way to having AK-3 functionality now. Fairly easy to do if anyone is wants to upgrade their AK-2. Quote Link to comment Share on other sites More sharing options...
JohnA Posted August 21, 2003 Share Posted August 21, 2003 Madisound.com has Hovlands, but PartsExpress has a line of polypropylene film and foil caps that may be just as good. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted August 22, 2003 Author Share Posted August 22, 2003 Finished the other Khorn last night, now I have the equivalent of AK-3's. The bass response seems better and the midrange more detailed. It is tough to tell with all 9 speakers playing I think I will shut the other amps down and play the Khorns by themselves to see. I will replace the iron core 4mh coil in the woofer circuit next along with the 13uf cap in the midrange circuit and that should just about do it. The big 100uf Solen Poly's were about $25 apiece, the 5mh coils were about $10 each. Even though they weren't the best available I certainly think they were superior to what was in there. Quote Link to comment Share on other sites More sharing options...
lovemyhorns Posted August 24, 2003 Share Posted August 24, 2003 I was looking at upgrading my AK-2 to an AK-3 and was looking at replacing that 13uF cap also, should it be replaced with a 13uF or would a 12uF with a 1uF be better?? Quote Link to comment Share on other sites More sharing options...
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