KLH 24 Tweeters are good - still no sound

[JeffKimm]

Just to preface this by saying i am new to the stereo game and this will be my first(ish) repair.
I have a pair of 1966 KLH 24 speakers. The subwoofer works and sounds good, the tweeters however, are not producing a sound. I already checked on the multimeter and they were reading 6.7 Ohms. I briefly connected them to a AA battery and they gave the little pop. I don't seem to be getting any voltage out of the wires to the speaker itself and from what I can tell, the crossover is just a coil and a capacitor. I am not sure what might be causing the tweeter alone to not play. Any advice would be great, Thanks.

 

[Leestereo]

The crossover capacitor is in series with the tweeter and it has failed open, resulting in loss of signal to the tweeter. Replacing the capacitor will restore the speaker's sound. KLH often used "Temple" branded capacitors (typically black cylinders with red ends) that are known to be failure-prone as they age

 

[hornbostel]

The KLH 24 (which is the same as the KLH 22) has a single 4 uF capacitor in the crossover circuit. There is no soldering required becuase the caps are wired to the rest of the circuit with wire nuts. Super easy.

 

[Tim D]

When you shop for the replacement cap you'll want to get a film cap or a non-polarized electrolytic of 35V or more handling (I'd recommend 50v). Most will recommend film caps but either are fine. Whatever you choose is gonna be better than what KLH originally used. Nice score btw.

 

[classic carl]

The subwoofer works and sounds good,

Welcome to AK. The KLH 24 did not have a subwoofer in the cabinet. It's called a woofer. As others have mentioned, your issue is probably in the crossover if all wires are connected properly to the tweeter.

 

[Tim D]

Welcome to AK. The KLH 24 did not have a subwoofer in the cabinet. It's called a woofer.

Lol. A sign of the times.

 

[classic carl]

Lol. A sign of the times.

True, but as long as he's here, he might as well be educated.

 

[bluepine27]

Just got three (3) KLH 24 speakers for 80 today and so far only tested two of them but seem to be good but will have to take a closer listen. Should I look into changing the caps even if the tweeter seems fine ? Also seems that changing the caps for most old speakers is recommended, is this more for longevity or sound detail?

 

[RxDx]

Yes. The typical caps KLH used are way past their prime, which can entirely
silence the tweeter.

 

[bluepine27]

When you shop for the replacement cap you'll want to get a film cap or a non-polarized electrolytic of 35V or more handling (I'd recommend 50v). Most will recommend film caps but either are fine. Whatever you choose is gonna be better than what KLH originally used. Nice score btw.

Any resource on where to get these caps?

Took some pics the of speakers, the one speaker with the RCA plug in on the back seems to be in good shape. The other two seem a little more rough. Any recommended way to undent this tweeter, vaccum, ect? the other tweeter doesn't seem to be horrible but seems really creased like it was dented and then forcibly pushed back out or something.

Also would love to get the cabinets to feel and look better too. They're a bit scratched and seem a little rough so would take some recommendations on how to restore the wood on these as well. Enjoying the sound so far out of these speakers and look forward to getting them in better shape.

 

[bluepine27]

Which value is more important to adhere to for the capacitor, the 4uf or the 50v handling? It seems I can find 4uf capacitors but not at 50v, just higher values. And it seems like I could find a capacitor at 50v but the uf value is rated for 4.7 instead of 4? Again, not sure which one is more important to make sure is on the mark.

 

[RxDx]

Higher voltages are fine. Stay within about 20% of original value. parts-express.com,
Dayton brand caps are common replacements.

Dented dust caps require some futzing to correct, but may not be affecting sound.
Common techniques are using tape to pull out the dent, getting the cap very slightly
moist and using vacuum, or using a needle to pop it out. I'd probably audition first to
see if I needed to bother.

Pictures will help determine what you need for cabinet refurb.

 

[bluepine27]

Higher voltages are fine. Stay within about 20% of original value. parts-express.com,
Dayton brand caps are common replacements.

So here's one for a film capacitor that's pretty expensive, 13 a capacitor but with the exact values as recommended by @Tim D
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/MMWA05W4K-F?qs=Xg8aCGofNLoWGVRxqEdZeQ==

And here's the close farad value of 4.7, 100v, non polarized for a lot cheaper
https://www.parts-express.com/4.7uF-100V-Non-Polarized-Capacitor-027-332

Any big differences here that could justify a 13 dollar difference in price per capacitor?

 

[RxDx]

Probably not on this speaker system.

 

[bluepine27]

I opened up one of the 24s. It looks like two things are taped together here. I couldn’t find any capacitors anywhere else so I assume this is one of them and not sure what the other thing is? Felt hesitant about peeling off the tape to really confirm, and dang there's a lot of insulation in this bad boi.

 

[RxDx]

Yeah, the black cylinder with the red ends is the old cap. It needs
to go. The other is the inductor for the woofer. Nothing to do with it.

 

[bluepine27]

ordered seven 4.7 uf caps to do all three KLH 24's and my Nova 15's, and Lafayette 1003's for a friend. Thanks for the capacitor guidance

 

[Tim D]

ordered seven 4.7 uf caps to do all three KLH 24's and my Nova 15's, and Lafayette 1003's for a friend. Thanks for the capacitor guidance

You done good going with the 4.7uF caps. Doesn't seem like there are mid-priced 4uF film caps around right now.

 

[bluepine27]

Messed up and made an assumption about the other KLH 24 I have that has the RCA input on the back rather than the pair of speaker wire posts 24's I have. The RCA version has one 8uf 50v cap and not the 4uf 50v caps.

I'm not sure if this is another cap. It looks like whatever material is on the outside is wrapped several times around in layers, maybe around a cap or maybe nothing. Didn't feel good ripping into it without knowing what it was. Feels like the wire is just towards an outside layer and not apart of a component. I'll find out in the morning but didn't know if someone knew what was up with the RCA input KLH 24's.

Swapping in the new 4.7 caps into the other two really helped clear up the sound though, highs are a little bit on the edge of crispy almost depending on the material but the overall clarity is much better. The bass is a little tighter and feels like it sucked in a little bit though and would like to find some ways to get some bass back. Looks like I'll be looking into the doping process

 

[Tim D]

The KLH 24 came in a couple of different versions. There are threads out there if you do a search with the big search engine tha will show you what others have dealt with. I can't tell from your picture, but if there is a square metal bar running through that part in your picture then it is the inductor and you can just leave it as they don't typically fail.

The KLH 24's with the RCA jack probably came as a combo system with a KLH 24 turntable. The RCA's were a fad back in the 70's to make connections easier - particularly for combo systems.