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Chorus 1 Midrange Woes


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Hey all,

Approximately three weeks ago, I picked up a set of generation 1 Klipsch Choruses--working perfectly, and in excellent cosmetic condition. However, after two weeks, the left channel's midrange started to crackle at high volumes, then cut out entirely. After testing a host of things (cables, amp channel, etc), I determined that the problem must be the speaker itself. Based on everything I'd read, that meant I'd need a new midrange diaphragm. Ordered a replacement. FFWD to today... new diaphragm arrives! I pull out the old one and replace it. (Note to my eye that the apparently-blown diaphragm looked perfect...) 

Plug in the speakers for a test... left midrange doesn't seem to be working properly still. Turned the amp up a bit and start fiddling with balance to confirm my suspicions.

 

Cracklecracklecrackle--CUT! 

I'm pissed--and clueless.

 

Did I just blow a second diaphragm? Did I not need a new one in the first place? Where is the problem coming from? The only thing I can think of at this point is the crossover, in which case I'm hopeless (I've never used a soldering iron in my life) and would probably be better off just getting an entirely fresh crossover in the first place. 

Any help here? 

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20 minutes ago, Somethingsfishy said:

I'm pissed--and clueless.

 

Did I just blow a second diaphragm? Did I not need a new one in the first place? Where is the problem coming from? The only thing I can think of at this point is the crossover, in which case I'm hopeless

Any help here? 

 

Hello and welcome, congrats on the new Chorus speakers, I'm sure once the bugs are worked out you'll be very happy with your purchase. 

 

An easy test at this point would be to swap mid horns between the two cabinets, that will let you know whether its the horn driver or the crossover.

 

If its the crossover really not a huge deal, they're 30 years old and could probably use a re-cap anyway just pull both terminal cups out leave the crossovers bolted right to them and mail them to Bob Crites for a rebuild, Last I checked it was about $150 and they'll be better than new and good to go for another 30 years. 

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5 minutes ago, Somethingsfishy said:

Is there any tangible advantage to getting the completely new Crites crossovers ($290) versus sending mine in for an overhaul? ($150) 

New xovers are a bit more $$'s ... decide if it's worth the extra money for being "without" speakers for 1-3 (???) weeks :D 

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First things first.  Swap drivers between cabinets and see whether the problem follows the driver or stays with the crossover.  Don't even need any test equipment for that action.  I would not be surprised if the same cabinet had the same symptoms, and would then check all the connections in/on the crossover as well the connectors on the ends of the wires going to the driver.  Crossover components would be the final thing to check if it gets that far.

 

That's my assumption and I'm sticking to it.

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First thing I would check would be taking the mids out and hooking them directly to the main speaker wire and play something at low volume with the bass turned all the way down just to see if I had output.  Then, I would go to crossovers next.  Element of reduction. And checking them with a DMM, too. 

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2 hours ago, glens said:

First things first.  Swap drivers between cabinets and see whether the problem follows the driver or stays with the crossover.  Don't even need any test equipment for that action.  I would not be surprised if the same cabinet had the same symptoms, and would then check all the connections in/on the crossover as well the connectors on the ends of the wires going to the driver.  Crossover components would be the final thing to check if it gets that far.

 

That's my assumption and I'm sticking to it.

Good advice and also check the banana plugs on the back to make sure your hookup is not just flopping around loose. Had a Chorus I recently that was really sour sounding but a recap fixed all that. That old you plan on doing it in any case because all of those old caps are out of spec and some of them probably badly so. Also loosen and re-tighten barrier strip screws if you have a crossover on a board. Take the spade ends and make sure they clamp tightly to the drivers and if they are loose take a pair of pliers to them and bend that little curved section closer to the back side of the spade end. Check solder joints to make sure they are good as I have seen some poorly done ones work loose.

  My favorite vintage speaker and well worth restoring and then upgrading.

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Midranges are fine. (swapped them, running in the other speaker) internal wires are fine. Something's definitely wrong on the crossover end of things. Seeing as they're 30 years old, I've decided to full-on nuke the problem by just ordering a set of complete Crites crossovers. (Turns out they had a set in stock!) 

 

Grabbed some titanium tweeters for good measure. In for a penny...

 

The good news is that now I have a spare midrange diaphragm if one ever blows! Stoked to return to shaking my house :D

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The new crossovers and diaphragms arrived today! Spent my afternoon redoing everything. 

 

The good news: 

LEFT MIDRANGE WORKS AGAIN! 

 

The bad news: 

 

One of the titanium tweeter diaphragms was DOA.

😩

Why oh why did I order them from eBay and not Crites? 

 

Blargh. Anyways, I should be able to swap it out easily enough—the eBay account in question is that of a large audio company. Never a dull moment... 

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1 hour ago, Somethingsfishy said:

The new crossovers and diaphragms arrived today! Spent my afternoon redoing everything. 

 

The good news: 

LEFT MIDRANGE WORKS AGAIN! 

 

The bad news: 

 

One of the titanium tweeter diaphragms was DOA.

😩

Why oh why did I order them from eBay and not Crites? 

 

Blargh. Anyways, I should be able to swap it out easily enough—the eBay account in question is that of a large audio company. Never a dull moment... 

OK try this. I ordered a set of Ti tweeter ones from Bob and put them in a set of K-792's. For some reason I decided to run a sweep on them and one was great the other one barely audible. Well heck brand new so whats up? There were three detente knobs on the driver and I remember reading about guys who used a sweep generator to dial diaphragms in just right so I thought all i can do is rotate the bad one 120 degrees and see. Absolutely nothing and then I rotate it again and perfect and the two match by ear. I don't know which one was eccentric and maybe both were but rotation solved the problem. Perhaps this will work here too.

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18 hours ago, Dave A said:

OK try this. I ordered a set of Ti tweeter ones from Bob and put them in a set of K-792's. For some reason I decided to run a sweep on them and one was great the other one barely audible. Well heck brand new so whats up? There were three detente knobs on the driver and I remember reading about guys who used a sweep generator to dial diaphragms in just right so I thought all i can do is rotate the bad one 120 degrees and see. Absolutely nothing and then I rotate it again and perfect and the two match by ear. I don't know which one was eccentric and maybe both were but rotation solved the problem. Perhaps this will work here too.

Wait, how do I rotate them? That's precisely my problem—one of them is barely audiable, the other is perfect. Do you mean rotate in the literal sense, as in within the driver? 

 

For the record, even with the slightly "lopsided" treble, the recap made a big SQ difference. I'm intensely skeptical about claimed SQ differences as a result of simply swapping components (not materials, volumes, sources, etc) but this was beyond dispute. Damn!!! 

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