KLH Model 6 silent tweeter

[cojobe]

Hello,

First off I apologize if I'm putting this in the wrong area or messing up formatting, this is my first post haha.
So I recently picked up a pair of KLH Model 6 speakers for $10. Physically they're good, no sign of abuse or anything. One sounds awesome, however the other's tweeter is making no sound. Only the woofer is.

After some research, it seems that it maybe be the "cap"?
If you can't tell already, I have a very very limited understanding of speaker wiring and repair. I have never opened one up for a fix. For this one I only unscrewed the tweeter cover just to see if anything was loose or disconnected
I've seen a one or two posts on here that explain it, but gloss over the details quickly as I'm sure most people understand the basics.

Any advise is appreciated! Thank you!

 

[Watthour]

Welcome Aboard!

I have a pair of the slightly larger Model 23, and they sound quite nice.

You will need to get into the enclosure to assess the situation. Many times that is accomplished by removing the 10" woofer, providing a hole through which you can work. There is likely at least a capacitor, and likely a resistor and a choke (inductor) in the crossover network separating the two speakers.

It will be helpful having a multimeter to check components, including the speaker voice coil resistance once you have gained access.

 

[roger2]

Look at the input terminals on the back of the speakers. There are three terminals labeled A, B and C. There should be a metal jumper bar connecting terminals B and C. If that jumper is missing the high frequency section is disconnected. I just looked at a few Model Six listings on ebay and in some pics that jumper was indeed missing. That would be the simplest cause for a tweeter to not be working.

Other possibilities are a blown tweeter, a failed capacitor, corrosion on the "High Frequency Level" switch, or (not highly likely) corrosion on or a bad connection of the B-to-C jumper. Try flipping that switch up and down a few times, then testing in each of the switch positions for sound coming from the tweeter.

If you remove anything (tweeter, woofer, input panel) you will break the seal and should take care to verify a good seal when any part is reinstalled into the cabinet. I have no idea what was used to create that seal, but it is important in sealed speaker designs to have a good seal. At the very least, when re-installing a driver (tweeter or woofer) that it be in the same orientation as original so that any imperfections in the sealing material match up between cabinet and driver.

 

[cojobe]

Look at the input terminals on the back of the speakers. There are three terminals labeled A, B and C. There should be a metal jumper bar connecting terminals B and C. If that jumper is missing the high frequency section is disconnected. I just looked at a few Model Six listings on ebay and in some pics that jumper was indeed missing. That would be the simplest cause for a tweeter to not be working.

Other possibilities are a blown tweeter, a failed capacitor, corrosion on the "High Frequency Level" switch. Try flipping that switch up and down a few times, then testing in each of the switch positions for sound coming from the tweeter.

If you remove anything (tweeter, woofer, input panel) you will break the seal and should take care to verify a good seal when any part is reinstalled into the cabinet. I have no idea what was used to create that seal, but it is important in sealed speaker designs to have a good seal. At the very least, when re-installing a driver (tweeter or woofer) that it be in the same orientation as original so that any imperfections in the sealing material match up between cabinet and driver.

View attachment 1891432

Hmm, mine appears to look a little different. There's no bar option, and I've flicked that switch a few times. Here's some photos of the inside and back.

 

[roger2]

Oh OK. I see several wire-nut connections. Those are strong candidates for failure. Just loosen the wire-nuts, verify that the ends of the wires are together, the re-twist. If you wanted to get fresh new wire-nuts it would probably be slightly better, but not absolutely necessary. Sometimes one wire will twist around the other and slide down to where it is not in good contact with the other wire(s) inside the wire-nut. In any case, it will not hurt to re-do all of those wire-nut connections as that is not the best possible connection method for longevity in lower voltage connections.

The caps appear to be film types, which are not likely to fail but it is possible.

A blown tweeter is a possibility. If the tweeter in one speaker works and the other doesn't, you can switch the tweeters from one cabinet to the other.Then you will know whether the problem is the tweeter driver itself, or the wiring/crossover.

 

[cojobe]

Oh OK. I see several wire-nut connections. Those are strong candidates for failure. Just loosen the wire-nuts, verify that the ends of the wires are together, the re-twist. If you wanted to get fresh new wire-nuts it would probably be slightly better, but not absolutely necessary. Sometimes one wire will twist around the other and slide down to where it is not in good contact with the other wire(s) inside the wire-nut. In any case, it will not hurt to re-do all of those wire-nut connections as that is not the best possible connection method for longevity in lower voltage connections.

The caps appear to be film types, which are not likely to fail but it is possible.

A blown tweeter is a possibility. If the tweeter in one speaker works and the other doesn't, you can switch the tweeters from one cabinet to the other.Then you will know whether the problem is the tweeter driver itself, or the wiring/crossover.

Good news! I think? I swapped tweeters, and it must be a blown tweeter because now the quiet tweeter is still quiet in the other speaker, and the good one remains working in the other cabinet.
So now my next question- this is a blown tweeter, correct? Do I just buy a new one, slap it in, and boom good to go?
If yes, which should I get? And do I get two to replace both tweeters so they sound the same? Not sure how that part works.

Thank you!

 

[HTHMAN]

So now my next question- this is a blown tweeter, correct? Do I just buy a new one, slap it in, and boom good to go?
If yes, which should I get? And do I get two to replace both tweeters so they sound the same? Not sure how that part works.

Thank you!

Yep. If the problem follows the driver, it is the driver. Your best bet is to try eBay for a single replacement.
https://www.ebay.com/itm/KLH-MODEL-...664866?hash=item2ae9794362:g:i6kAAOSwN9ZezDt7
Others may chime in if any of the other models used the same driver. If you get a non original replacement. you will need to replace both.

 

[roger2]

I agree. The best thing to do is get an exact replacement if possible, even if it is used. Any replacement will change the sound of the original design, to some unknown degree.

The good news it that you have identified the problem. The bad news is, a blown tweeter is what you wanted least to discover.

Another point to throw into the mix: apparently there are (at least) two versions of Model Six. They may not necessarily have the same tweeters (or woofers or crossovers).

.

 

[cojobe]

Sounds good, so the hunt begins.
And to be honest I was hoping it was this since I didn't really want to fuss with the caps. Just glad I know what the problem is regardless.

Thanks!

 

[roger2]

In the mean time, there is no harm in enjoying your speakers with one tweeter not working.

 

[cojobe]

In the mean time, there is no harm in enjoying your speakers with one tweeter not working.

Absolutely! This will give me time to refinish the veneer as well. Thanks again