dtr20 Posted November 7, 2016 Share Posted November 7, 2016 So we are rebuilding my father's ( @TomR ) chorus it's that we picked up a little while ago. We were told that it had a crossover issue because the mid-range didn't work on one speaker. He needed to get the passive rebuilt as well. When I got them home and started taking them apart to do a restore on the cabinets, I realized both mid-ranges were hooked up wrong. They had positive and negative wires hooked to the same terminals on the mid-range. We got the passive back, put everything back together and realized there was indeed an issue with one mid-range. We swapped mid-ranges and the problem stayed with the crossover. I had a friend recap the crossovers and they sound a ton better. We were listening to them this weekend and heard static coming out of one mid-range. We swapped mid-ranges, stayed with the crossover, swapped left and right speaker cables, and stayed with crossover. The static isn't always there, but is very noticeable and repeatable with the beginning to sweet emotion by aerosmith. Does anyone have any ideas? Could hooking up the mid-range wires to one terminal (essentially causing a short) fry the crossover? My friend is going to check it out when I can get it to him hopefully this week. Quote Link to comment Share on other sites More sharing options...
wvu80 Posted November 7, 2016 Share Posted November 7, 2016 Did the static problem exist prior to the XO rebuild by your friend? When the XO's were put back in, did the static start right away, or was it NOT there, then came back in? I know this is a basic suggestion, but I like to start with the place that is easiest to check; completely take your speaker wires off both ends, then reinstall them. If you have banana plugs, check them for a secure connection as well. Quote Link to comment Share on other sites More sharing options...
dtr20 Posted November 7, 2016 Author Share Posted November 7, 2016 Before the rebuild, the mid-range pretty much just made an annoying noise, static, sounds would cut in and out, etc. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 7, 2016 Share Posted November 7, 2016 Are there screw terminals on this particular crossover and if so are they all tight? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 7, 2016 Share Posted November 7, 2016 If you have one KNOWN good crossover, you can sit them side by side on a bench and check them at different spots on the crossover. Compare the two. If you get vastly different readings in one particular area, you've found your problem. Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted November 7, 2016 Share Posted November 7, 2016 12 minutes ago, CECAA850 said: Are there screw terminals on this particular crossover and if so are they all tight? I would add: Are there screw terminals on this particular crossover and if so are they all CLEAN and tight? Quote Link to comment Share on other sites More sharing options...
BEC Posted November 7, 2016 Share Posted November 7, 2016 That is a Chorus II. Crossover is on a PC board attached to the back of the input terminal cup. No terminal strip, so no screw terminals. Quote Link to comment Share on other sites More sharing options...
dtr20 Posted November 7, 2016 Author Share Posted November 7, 2016 We are using banana plugs on these speakers. Like I said earlier, one speaker works fine, the other doesn't, even after we switched the left and right speaker cables. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted November 8, 2016 Share Posted November 8, 2016 I'd say that one crossover is toast, even after the recap. Send em both to Bob for a rebuild. 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted November 8, 2016 Share Posted November 8, 2016 Are the wires from crossover to mid driver good? Can you lightly shake the wire and cause the problem? I know nothing about these particular models. Looks like its a solder joint at the crossover per Bob's photo. Are the solder joints good? What about at the speaker/driver? Are they crimp contacts? Remember when music is a playin' the wires could be shakin' 1 Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 8, 2016 Share Posted November 8, 2016 ^^ What he said... At this point I would make a "guess" that it is a cold solder joint. Sometimes they look perfect, but not even connected. Just reflow the solder on all the joints and check. It usually doesn't happen on the connections with multi stranded wire, but on the components with a solid conductor. Bruce Quote Link to comment Share on other sites More sharing options...
babadono Posted November 8, 2016 Share Posted November 8, 2016 DTR20, are you saying that both mid range outputs the + and - were tied together at the driver? Or both terminals of the driver were tied to the same point on the crossover? Here's he crossover schematic from elsewhere on this forum: Quote Link to comment Share on other sites More sharing options...
dtr20 Posted November 8, 2016 Author Share Posted November 8, 2016 On the mid-range drivers on these speakers, the terminals for the wires are in the shape of a U. I'm guessing this is so the builder could easily connect the wires to the driver however he grabbed it. They wouldn't need to check top or bottom. Both positive and negative were connected to one of these terminals. I do not know if they attempted to drive the speakers while hooked up this way. Quote Link to comment Share on other sites More sharing options...
oldred Posted November 8, 2016 Share Posted November 8, 2016 54 minutes ago, jimjimbo said: I'd say that one crossover is toast, even after the recap. Send em both to Bob for a rebuild. +1 to that....send both to Bob....let him got through them.....that's what he does..... G.E.M. Quote Link to comment Share on other sites More sharing options...
babadono Posted November 8, 2016 Share Posted November 8, 2016 So Bob @BEC or any other crossover expert, could shorting the + and - midrange outputs of the crossover damage the crossover? I wouldn't think so but I'm not an expert. Quote Link to comment Share on other sites More sharing options...
babadono Posted November 8, 2016 Share Posted November 8, 2016 15 hours ago, dtr20 said: On the mid-range drivers on these speakers, the terminals for the wires are in the shape of a U. You got a picture of this? Anybody? Quote Link to comment Share on other sites More sharing options...
dtr20 Posted November 8, 2016 Author Share Posted November 8, 2016 Quote Link to comment Share on other sites More sharing options...
wvu80 Posted November 8, 2016 Share Posted November 8, 2016 The picture helps clear things up! Two terminals on each end. I could NOT figure out how the driver could be mis-wired, but it sure could be. Have we determined the problem is NOT in the compression driver? (I'm just double-checking) +++ If so I am also throwing in with others ^^^ who have suggested a bad solder joint on the XO itself. I wonder if the wires are properly (no movement) soldered into the board. Disclaimer: I am not an electronic tech, just a regular guy trying to help diagnose a static noise. Quote Link to comment Share on other sites More sharing options...
jjptkd Posted November 8, 2016 Share Posted November 8, 2016 20 hours ago, dtr20 said: I realized both mid-ranges were hooked up wrong. They had positive and negative wires hooked to the same terminals on the mid-range. This happened to me as well with a pair of KLF-30's that I bought awhile back. They were being sold cheap so I didn't really do any in depth listening at the seller's house, just wanted to get them home. When I hooked them up at home they sounded really, really bad, I couldn't believe it. After further inspection I realized that neither of the mids were working at all. When I removed them from the cabinet they were both hooked up the same way as described above. I simply hooked them up the correct way and boom, back in business! No apparent problems with the crossovers, in fact my brother still uses these speakers today a few years later. I would double check the female connectors on the crossovers leads to all the drivers and make sure that they are really tight. I know they have a tendency to loosen up when removed and put back on. As a rule I always crimp them back down with pliers before re-installing. Also, cold solder joint is a good possibility as mentioned before, wouldn't take much to touch them up. If that doesn't work I'd send them to Bob Crites. Quote Link to comment Share on other sites More sharing options...
dtr20 Posted November 8, 2016 Author Share Posted November 8, 2016 12 minutes ago, wvu80 said: Have we determined the problem is NOT in the compression driver? (I'm just double-checking) Yea, midrange driver works fine in the other speaker when swapped. Quote Link to comment Share on other sites More sharing options...
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