Where's there's a will...there's relatives. Solving the dreaded KLH 6 capacitor problem easily

[soundminded]

Some very kind person gave me a pair of KLH6s this weekend. One was the relatively newer version with the steel frame woofer and the other was the old version with the epoxied woofer. And the tweeter in the old one didn't work. The grill cloth was gone. I removed the 4 screws holding the tweeter, cut the wires so that all ends were accessible and there was sufficient wire left on the tweeter itself (it's soldered to the tweeter and if you break it or damage it, you've got a problem.) I inspected the capacitor which is right next to the opening with a flashlight and a dental mirror, and started removing the hold down screws with my hand working through the tweeter opening (you can get your arm in there with a screwdriver for unscrewing it.) That wasn't even necessary. When I got it out, I realized it was just 2 4 mfd caps in parallel so I scrounged around in my parts box and tied 3 2.7 mfd 100 volt NPC caps in parallel (close enough for government work) soldereded it all back together, taped all the connections, fluffed out the fiberglass, screwed the tweeter back in and voila, repaired and good as new. I'm thinking of doing the other one just for the hell of it. No reciprocating saw, no removing the woofer cone, no nothing, a surprisingly simple repair. Now all I have to do is get some masonite and some cloth and make a new grill cloth. Who knows, one day when I get ambitious, I may just refinish the cabinets.

[Andy]

Sounds like a successful repair and well worth the effort. On pevious posts, all the talk about how to get inside early KLH speakers was due to the fact that both woofer and tweeter were epoxied in. I'm not sure what year the screw in tweeter was introduced ( 1963 ? ) but it made repairs much easier. I'm holding by breath on my 1958 Model Sixes, they sound great, but have epoxied drivers and have very nice 12-ply marine plywood cabinets which are scarce, and I don't think I could bring myself to saw open.

[soundminded]

OMG, they epoxied in the tweeters too on some versions? Why would they epoxy in the tweeters? I've got another early pair which I bought used in 1965 and here I thought now I'll get away easy. If I have to work on those too and they are expoxied in, I think I'm going to get them out from the front one way or another. BTW, there is NO subenclosure for the tweeter and the back is exposed to the pressure wave from the woofer. An oversight? Doesn't seem to matter though.

[dynaco_dan]

>OMG, they epoxied in the tweeters too on some versions? Why

>would they epoxy in the tweeters?

Hi there;

My best guess is that, they epoxied the woofers and tweeters in to unify the drivers and the enclosures.

Sort of, to make it all one unit, a more rigid system, to eliminate seals and resonances.

It was a new idea, developed by whom?

Maybe Henry Kloss?

It would be nice to have a partner, engineer or worker that was involved in it's conception.

With Henry passing away, we may never know.

I have already read of the detailed repair, where the woofers cone was ripped out to do any internal repairs.

I've got another early pair

>which I bought used in 1965 and here I thought now I'll get

>away easy. If I have to work on those too and they are

>expoxied in, I think I'm going to get them out from the front

>one way or another.

BTW, there is NO subenclosure for the

>tweeter and the back is exposed to the pressure wave from the

>woofer. An oversight? Doesn't seem to matter though.

This would be a really big mistake.

Can you see that the rear of the tweeters sheet metal, has openings?

Usually the tweeters and mids have totally enclosed rears.

A sub-enclosure is usually used in the case of open-backed midrange drivers.

Philips use to make a mid-range/full-range driver and it was available with or without a shell covering.

To have an open backed tweeter and or mid driver is an accident waiting to happen.

If the tweeters cone/surround is open, then the back pressure from the woofer can easily blow it out, to vent internal pressure.

I suspect that the tweeters rear is fully enclosed.

Good luck.

[Guest ddavejb]

I own pairs of both Sixes and Seventeens and although there are no sub-enclosures for the tweeters, the tweeters themslves are solid unperforated metal in back.

I have some Harman Kardon HK-40's, on the other hand, that have open back tweeters that are sealed with little plastic sub-enclosures filled with fiber glass attached to the tweeters themselves.

Vern is right in that if any cone tweeter were subjected to the backwave of a woofer, they wouldn't last long at all.

Enjoy those Sixes. For sheer simplicity of design and quality of sound and construction they can't be beat.

[dynaco_dan]

>I own pairs of both Sixes and Seventeens and although there

>are no sub-enclosures for the tweeters, the tweeters themslves

>are solid unperforated metal in back.

>

>I have some Harman Kardon HK-40's, on the other hand, that

>have open back tweeters that are sealed with little plastic

>sub-enclosures filled with fiber glass attached to the

>tweeters themselves.

>

>Vern is right in that if any cone tweeter were subjected to

>the backwave of a woofer, they wouldn't last long at all.

Hi there;

Of course, if they had designed the tweeter to also act as a passive radiator, this would make for some interesting reading, heh? lol lol

>Enjoy those Sixes. For sheer simplicity of design and quality

>of sound and construction they can't be beat.