Epoxy'd KLH Model 6: how to beat your way inside....tweeter cap replacement

[Guest bobknobsky]

Just finished replacing the limiter caps to the tweeters on my 6's. This is the most typical failure in ALL KLH's from my experience. Tweeter goes quiet: but Rarely is the tweeter the problem. Good quality non polar caps are available everywhere: the key is to sneak them into the 6's from the back. Warning: not pretty, messy, but can be quick and easier than you think: Remove rear hardware: all of the nuts, lock washers, insulating washers from the binding posts (terminals) and HF 3-way switch. Gently pry up the rear plate around each nail and pull the 8 nails. Wiggle everything and work the plate off. You're now looking at a solid block of epoxy filling the back of a 3 by 3" square hole. Get a roofing hammer and a rusty Railroad Spike and crush it. Yep. That was Easy. Now get all the shards of epoxy out of your eyes, hair and especially out of the edges of that hole: because you're sticking your hand in there and you better have small hands. (try using the one that you don't use when you're not on the Classic Speaker Pages) If you want to look around, you'll have to start pulling the wads of fiberglass out: don't. Pull the glass downward and feel around the front board between the tweeter and woofer: you'll feel an inductor coil: feels like a spool of solder, and next to it is the paper cap: about the size of a vienna sausage with 3 wires sticking out of one end: He's your man. Now, go back in there palming some snips and cut the wires as close to that sausage as you can: Leave the dang thing in there glued to the board! Pull out the wires and splice your new cap in between the black wire and the red wires (you just need to use One red actually. Tape up the other red end. If you want to do a quick test: connect the black to the red and Hook up your speaker wires directly to what was the terminals: black to Neg and red+blue to pos: and play the speakers Quietly: the tweeter should now work....? Good! Install the cap, shove it in the hole and Now decide how far you want to go packing and sealing up that hole when you put it all back together. And Don't mess up the insulator washers on the terminals! That's a metal plate! Took me about 20 mins each.

[dynaco_dan]

>Just finished replacing the limiter caps to the tweeters on

>my 6's. This is the most typical failure in ALL KLH's from my

>experience. Tweeter goes quiet: but Rarely is the tweeter the

>problem. Good quality non polar caps are available everywhere:

>the key is to sneak them into the 6's from the back. Warning:

>not pretty, messy, but can be quick and easier than you think:

>Remove rear hardware: all of the nuts, lock washers,

>insulating washers from the binding posts (terminals) and HF

>3-way switch. Gently pry up the rear plate around each nail

>and pull the 8 nails. Wiggle everything and work the plate

>off. You're now looking at a solid block of epoxy filling the

>back of a 3 by 3" square hole. Get a roofing hammer and a

>rusty Railroad Spike and crush it. Yep. That was Easy. Now get

>all the shards of epoxy out of your eyes, hair and especially

>out of the edges of that hole: because you're sticking your

>hand in there and you better have small hands. (try using the

>one that you don't use when you're not on the Classic Speaker

>Pages) If you want to look around, you'll have to start

>pulling the wads of fiberglass out: don't. Pull the glass

>downward and feel around the front board between the tweeter

>and woofer: you'll feel an inductor coil: feels like a spool

>of solder, and next to it is the paper cap: about the size of

>a vienna sausage with 3 wires sticking out of one end: He's

>your man. Now, go back in there palming some snips and cut the

>wires as close to that sausage as you can: Leave the dang

>thing in there glued to the board! Pull out the wires and

>splice your new cap in between the black wire and the red

>wires (you just need to use One red actually. Tape up the

>other red end. If you want to do a quick test: connect the

>black to the red and Hook up your speaker wires directly to

>what was the terminals: black to Neg and red+blue to pos: and

>play the speakers Quietly: the tweeter should now work....?

>Good! Install the cap, shove it in the hole and Now decide how

>far you want to go packing and sealing up that hole when you

>put it all back together. And Don't mess up the insulator

>washers on the terminals! That's a metal plate! Took me about

>20 mins each.

Hi there;

I have not owned these epoxied KLH Six speakers.

I have read lots of stories about them, though.

Access from the rear appears to be the only option, today.

My thoughts are based somewhat on the earliest AR-LST's enclosures.

They cut out a piece on the rear of the enclosure and routered out a shelf to support the crossover panel, which sat on this ledge to make it sound simple.

We can't do that, but, what if, a sabre saw, set at an extreme angle is used to cut out a circle or rectangle larger than the crossover area.

There is the allowance for the blade thickness, but with the angle of the cut, that piece cannot fall into the enclosure, if it is quite round, that is.

Perhaps a temporary sealant (putty) can be used to reseal this gap and small wood screws at an opposing angle can refasten them.

There is a good seal and permanent access as well.

A fine blade will leave less of a gap of course.

A circle will probably be stronger.

Just a thought.

[Guest farzhan]

I've read about this somewhere, if it wasn't here it must have been audiokarma but somewhere this has been discussed in depth and the consensus was that you can cut out part of the back and make it so it can be sealed and reopened. I'm just glad I bought a later pair with velcro grills and drivers held in with screws.

[Guest dbradley]

I got a pair of 6's with the tweeters not working (very faint sound only at high levels of drive and the tweeters and woofers epoxied in (serial numbers around 84000). I read a lot of the earlier posts in this website, and proceeded to do what the other replies to this post suggest, namely cutting open a 12x18 inch rectangle on the back with a sabre saw set on a 45 degree angle. When I opened it up, I found that on the other side (the inside) of the epoxy behind the posts on the rear wall you describe, there were a couple of caps/resistors wired in, which I assume enable the high frequency increase/reduce switches next to the posts to do their job. I only mention that because if you took the roofing hammer/railroad stake approach you describe, you would probably do some damage to whatever those things are. Since I lack the electronic testing equipment, I have now taken the speakers, which I had opened up, to my stereo repair guy to test and either replace the caps or tell me if I need to replace the tweeters, which neither he nor I expect. Then I plan to seal the openings up airtight with metal and rubber strips, so I can reopen them if they ever break down again, and then I will refinish the walnut veneer by sanding and oiling. A lot of work, but well worth it for a great pair of 6's.

But you may want to hesitate with the hammer. My understanding is that the design of the 6's changed substantially over time so some may not have the same electronics on the inside wall of the posts. But mine did.

[Andy]

That sounds like the way to do the job with little damage. Does anyone know at about what serial number KLH switched from oil filled caps to the paper type? I've read that the early oil type were War surplus and were very durable, not likely to fail. My 6's are very early, numbers 0684 & 0711 placing them to the spring of 1958.

[Guest dbradley]

All I can tell you is my KLH 6's, as I said, are serial number 84000 roughly, which I was told places them in the 1965 range and they have oil caps.

[fixtillbroke]

Pull the glass

>downward and feel around the front board between the tweeter

>and woofer: you'll feel an inductor coil: feels like a spool

>of solder, and next to it is the paper cap: about the size of

>a vienna sausage with 3 wires sticking out of one end: He's

>your man. Now, go back in there palming some snips and cut the

>wires as close to that sausage as you can: Leave the dang

>thing in there glued to the board! Pull out the wires and

>splice your new cap in between the black wire and the red

>wires (you just need to use One red actually.

Could you tell me what capacitor you selected to replace this defective "vienna sausage" with the three wires at one end? I need to do this same job to a pair of 17's

[Horswispr]

A friend and I just acquired a pair of KLH 6s on Ebay. I've been refinishing cabinets of early '70s speakers (mostly Dynaco A-25s) and wanted to hear what KLH 6s sounded like. Upon first listen, these things sound remarkably good! They sound maybe just a tad warmer and more mellow than A-25s and a bit less bass-heavy than Large Advents.

I wanted to take the front grilles off to have a look at the drivers but I can't. I've taken grilles off of many Dynaco A-25s and one pair of KLH 17s but these things ain't budging. Is that par for the course?

My main question is as follows: Are the woofer surrounds of the KLH 6s of a material that rots, like many speakers of the early 70s? Or can I assume that the surrounds (which I can not look at) are OK?

Also, I invite others' comments about the sound of these speakers. I'm listening to Miles's Kind of Blue right now and will soon check out some of my other reference CDs. The sound is quite mellow and enjoyable, with perhaps more "roundness" than they A-25s provide. The highs are surprisingly good.

Any comments are appreciated, as this is the first pair of KLH 6s I've had the pleasure of working on.

[Guest Feighner]

I have Six's in the 27000 range with oil caps.