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EasyWriter

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I am attempting to restore my college-era KLH17 speakers, largely relying on advice and wisdom from this web site. This project is pushing the boundaries of my knowledge, which is good but challenging.

I'm sure it's my fault and not yours, but it's not going well. I replaced the three capacitors on the first speaker, and my tweeter is silent. The woofer works.

The capacitors are from Dayton Audio and specs are visible in attached images. I left the leads at full length and used a metal clip for a heat sink between the capacitor and solder point. I think my solder joints were good. I covered the bare leads with heat-shrink tubing. I didn't remove the existing resistors, so their configuration is unchanged.

I've drawn an amateurish diagram of my resulting wiring. 

I have a multimeter, but I'm new to it, too, and not sure what I should be testing.

Thank you very much for your help. I'd come mow your lawn, if I could, to show my thanks.

SpeakerWiring.jpg

IMG_9036.jpg

IMG_9041.jpg

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Hmmm... I don't see anything wrong but maybe someone else will. Schematic attached below. Are you sure the tweeter works? btw, I'm reading Springsteen's autobiography now and cracked up at the Monkey Man reference.

17_SCHEMATIC copy.jpg

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@Jkent,

Thank you so much. You're the patron saint of my project.

I'd wondered whether the tweeter might be bad, but I don't know how to test beyond the circumstantial evidence.

Is it possible that the 8.2uf capacitor is bad? I have voltage going into it but not coming out. The voltage jumps with the music, it seems, so I can't give you a specific reading, but it's generally about 0.5mV, it seems to me. Except it's 0 on the speaker side of the capacitor.

I'm glad you enjoyed the Monkey Man reference. That song starts running through my head whenever I work on this project.

 

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You can hook up the tweeter directly to the signal source at very low volume and you should hear the music but very tinny.

I asked Roy to take a look at this. He knows far more about crossovers than I do.

Hang in there.

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You might check that the insulating washers around the binding post are installed properly because it could be grounding out on the metal plate. Definitely check the tweeters with the ohms function of your multimeter. I have seen several 17 tweeters come to life when the caps were replaced. Check your solder joints again, evan the ones at the tweeter terminals.

Always look at the simplest things first.  You will be successful. 

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That tweeter is dead.

Thank you for your suggestions for what to test. I started with the tweeter because my soldering skills are good, even if I don't understand the circuit. 🙂

It zeroed out on the ohmmeter, and connecting it directly to the terminals yielded nothing but the sound of silence, and I don't mean the Simon & Garfunkel song.

I'm determined to revive these speakers, so now I'll be shopping for some 4-inch, 8-ohm tweeters. Recommendations welcome.

And you don't know how much I appreciate your help. @jkent @IARbybody

death3.jpg

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10 minutes ago, EasyWriter said:

I'm determined to revive these speakers, so now I'll be shopping for some 4-inch, 8-ohm tweeters. Recommendations welcome.

Good! Check ebay. Generally, if you find a KLH tweeter that looks like yours it will be right.

Edited your photo ;)

DOA.jpg

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How important is it to get KLH specifically? I see some other brands, especially Dayton Audio and Goldwood, that look good.

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If you use a different tweeter it will no longer be a KLH Seventeen. AND you will probably need to make crossover changes. There is a lot of art and science to designing a speaker system and unless you know what you're doing you're better off not changing anything. 

These look like they may be right (I don't have Seventeens here to compare) https://www.ebay.com/itm/Klh-tweeters-fit-many-50s-70s-models/303042850572?hash=item468ec2ef0c:g:LVUAAOSwRfxcTiEy:rk:1:pf:1

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Just a couple of questions.  Is there a difference between the bright finished tweeters and the black finished tweeters. I have both kinds in different sets of 17's. Second question. Are the tweeters in my Model 20 speakers different because they are 4 ohm speakers?   

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Easy: The listing refers to DC Resistance, not speaker impedance. You can check your other tweet with an ohmmeter to be sure but 4 ohms DCR sounds about right.

Larry: The paint color doesn’t matter. And the 17 and 20 are exactly the same except for the woofers. Tweets are the same.

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Kent: Thanks for confirming that the tweeters are the same. Sort of like the AR3 phenolic dome tweeter also being used on the AR2a and early AR2ax speakers even though the later two are 8 ohm speakers. The KLH 17 and 20 woofers are the same except for their voice coil windings.

Upon some further reading it seems that a lot of open Model 17 tweeters are caused by breaks in the tiny voice coil wire leads.  If you can cut and pry off the mesh covers you might find something like this.

hZ5XZGJb.jpg

 

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