KLH Tweeter ID and Repair

[boreas]

AFAIK, all have interchangeable tweeters. I'm not sure about the others but they are also probably the same.

The tweeters are indeed interchangeable but it has long been maintained by folks in forums like this that there are two types, one slightly different from the other. One type was developed for the Model Six and can be found also in the Seventeen, Twenty, Thirty, Thirty-Three and perhaps others. The second type, developed for the Model Twelve, can also be found in the Five and Twenty-Three.

These are designated, and sometimes marked, M-12 and can be distinguished from the Model Six type by the thickness of the "top", or inner plate of the magnet assembly. On the Model Six type the top and bottom plates are the same thickness but the top plate on the Model Twelve type, the M-12, is significantly thinner than the bottom plate.

There is a KLH service bulletin, #59, in the library at the Classic Speaker Pages. It was mentioned early in this thread. On the chance that you missed it, I've attached it to this post. The photos are terrible and the description only says that the top plates are of "different thicknesses" but we've seen in this thread examples of the M-12 and the "M-6"? tweeter which show that the M-12 has the thinner of the two top plates.

The information about two different tweeters has been around for a while but it has never been clear, at least to me, exactly how to tell one from the other. We now have authoritative information from the original source concerning the different top plates and information from posters here as too the exact nature of that difference. We also have learned that the screen is affixed to the flange with a different color adhesive for each type, a sort of putty or khaki color for the Model Six tweeter and a darker more or less honey color for the M-12.

So, this sort of encapsulated the knowledge gained in this thread over the course of some 40 posts. Hope this helps.

John

 

[audiojones]

Not to mention the interview with Henry Kloss (it's out there somewhere, I have to try and find it again) in which he mentions that the Model Five / Twelve / Twenty-Three tweeter is damped differently and changed a bit internally from the others. If you listen to them side by side you can hear the difference, especially in the midrange response. They look almost identical and they measure the same electrically, but there's a bit more to it than that.

 

[4everanalog]

Tweeter grill

Hi there,
Lots of great info here.
Is there any reason that metal grill is on the tweeter other than as a physical barrier? Is there a sonic purpose behind it? I know JBL did something along those lines on one of their tweets to knock out some of the harshness.
Kind of curious if the highs would be more forward if played with the grill removed.
Anyone here ever tried this?
Regards.

 

[GD70]

Hi there,
Lots of great info here.
Is there any reason that metal grill is on the tweeter other than as a physical barrier? Is there a sonic purpose behind it? I know JBL did something along those lines on one of their tweets to knock out some of the harshness.
Kind of curious if the highs would be more forward if played with the grill removed.
Anyone here ever tried this?
Regards.

My guess it's for protection. There's VERY thin wires going to the VC that easily break.

 

[boreas]

I've heard it said that the screen serves an acoustic purpose. ADS produced quite a few speakers where the entire grille was made from a similar material. They claimed that the grilles were a part of the whole sonic package.

John

 

[clarkson]

Wow,great thread with a ton of info. Thanks ,this one is bookmarked.

 

[doctorolds]

My Twenty-Three tweeters are silver but, except as noted regarding the black spray paint, I've never found the color to be diagnostic. Some are silver and some are faintly gold in color. (anodized?)
John

I believe that this is a picture of the anodized tweeter you have described. I copied the picture from an ePay listing and have emailed the seller to see if the tweeter was pulled from an original, un-opened KLH 6 Model speaker since the add states that is where it came from. I also requested a picture from the side to see the magnet structure. I will provide an update if I get a response.

 

[fucanay]

Yes, definitely use copper wire. I usually pull some stands of fine copper wire to do this repair or else I'll use the braided copper voice coil connection wire from a junk speaker (that braided wire that goes from the terminal strip to the cone connection).

If the break in the voice coil wire is below the cone then you're out of luck on that tweeter. If you can get an ohm reading at a point above the cone then that's where you make your connection with the new wire. If you only get an ohm reading when you push in on the cone then you're out of luck, that means the break in the wire is below the cone.

Hope this helps!

I know this is old and I don't know if you're still watching this thread, but I am in this situation right now. I have found where the broken point is and confirmed the coil still has continuity. But I do have a question. That wire is VERY thin. At what temp did you solder the patched wire. Mine was broken under the glue on the hard brown surround area. I now have if free from there and there is quite a bit of length from the point where it goes into the cone, but obviously I'm going to have to patch a thin copper wire in and I'm afraid to melt it.

 

[doctorolds]

I know this is old and I don't know if you're still watching this thread, but I am in this situation right now. I have found where the broken point is and confirmed the coil still has continuity. But I do have a question. That wire is VERY thin. At what temp did you solder the patched wire. Mine was broken under the glue on the hard brown surround area. I now have if free from there and there is quite a bit of length from the point where it goes into the cone, but obviously I'm going to have to patch a thin copper wire in and I'm afraid to melt it.

Well, you are part way there. I would say use a low to medium heat for the temperature. Try soldering two pieces of the new wire to itself and see how it goes. I would suggest that you first make sure that any coating is removed from the wire, clean it well, and use a small amount of flux. Good luck.

 

[bentvinyl]

How do I remove the tweeter grill so I can get into the cone to work on it? I tried using a blow dryer to heat up the brown adhesive but no luck. Sorry for bringing back such an old thread but I figured I'd start here before making my own thread.

 

[doctorolds]

I used a small knife as can be seen near the middle of the first page of this thread. Good luck.

 

[bentvinyl]

I used a small knife as can be seen near the middle of the first page of this thread. Good luck.

Thanks I was finally able to get the grill off now I'm curious, how do I get into the wiring to check if I can fix it?

 

[GD70]

Thanks I was finally able to get the grill off now I'm curious, how do I get into the wiring to check if I can fix it?

If you can't see any breaks in the wire's then unfortunately it's un repairable.

 

[t j]

New vs. old... The new one has a different finish on the plate, has no M-12 stamp and meters out at 4.5. It is said to have come from a Model-5...

Any thoughts

 

[audiojones]

New vs. old... The new one has a different finish on the plate, has no M-12 stamp and meters out at 4.5. It is said to have come from a Model-5...

Any thoughts

Those are both from Model Five / Twelve / Twenty-Three speakers. Note the thin plate between the magnet and the back of the speaker frame, also the dark brown glue vs. the tan glue. The M-12 stamp comes and goes on all sorts of things, not sure what it means but it's not a reliable ID tag. Apparently it doesn't mean Model Twelve because I've seen that stamp on Seventeen and Twenty cabinets, crossover parts and other stuff. Guess it must be a factory code or something.

 

[Joe Nardy]

I realize this is an older thread but there's a lot of good info here which will hopefully help yet another guy with KLH tweeter identification problems. I recently picked up a pair of Model 23 speakers, one of which has a dead tweeter. I removed the metal grill and checked for broken voice coil wires but found none and the leads measure infinite resistance so it's really dead. I posted a 'Want To Buy' thread in Barter Town and received a response from someone saying they have a KLH tweeter with a metal screen on it but they aren't sure what model it came from. I have read through this entire thread and understand that there are two different tweeters that look very similar but are actually different and that there are some physical characteristics that may or may not distinguish between the two types. I'm going to post pics of my dead tweeter and hopefully pics of the good spare sometime soon and ask for your help in attempting to identify what each is.

Here's the dead tweeter:

Front view. No 'M12' or other markings on the housing


Back view


Side view. Plate closest to basket is thinner than the plate furthest from the basket



Are these pics enough to verify this is indeed the correct tweeter for a Model 23 speaker? I have no knowledge of the history of these speakers so I can't say whether the drivers are original or not.

Thanks,
Joe Nardy

 

[RxDx]

 

[doctorolds]

Correct ^^^
It's actually simple, if the two plates are the same thickness then it's not a 5, 12, or 23. Judging from your picture your tweeter is correct.

 

[Joe Nardy]

View attachment 1928079

Correct ^^^
It's actually simple, if the two plates are the same thickness then it's not a 5, 12, or 23. Judging from your picture your tweeter is correct.

Well, that's much simpler than the previous 55 posts indicated. Many thanks to both of you!

Joe