KLH model four

[Guest archie]

Hello, this is my first post on this site so I hope I post in the right thread, KLH.

I recently bought a pair of KLH Model Fours. The twin tweeters do not work in one of the speakers. From the research I've done It's most likely the caps, not the tweeters. Problem is the cabinets are completely sealed and the drivers are epoxied to the front baffle. I've managed to removed the grills without breaking them but that does me no good in accessing the caps. I know I can cut through the back but I'm wondering if carefully prying up the back plate will access the caps. Unless they are glued on the back of the front baffle? Suggestions welcome.

[Guest archie]

I should say suggestions welcome and much appreciated.

[Guest archie]

And I forgot to introduce myself. My name is Ray and I've been collecting audio stuff for nigh on 50 years, so I'm old, which is why I sometimes forget things. No formal training, just playing it by ear (no pun intended). I don't consider myself an audio sophisticate, I only have a small collection of vintage speakers. So far my skills are confined to recapping and refoaming along with some cabinet restorations.

[Andy]

This is the bane of early KLH collectors, and a tough one. We've had input on this forum in the past with several ideas....one can pry the cabinet open at the baffle board, but certain KLH cabinets were very well put together - as in the 12-ply marine plywood with rabbet joints at the corners. I couldn't bring myself to do this, the sound of cracking speaker cabinet wood gives me chills! The method I think is best is to cut a round hole in the back or the bottom of the cabinet with a bevel of say 45 degrees. This way when put the piece back in place it will fit like a cork in a bottle. This could be sealed with a compound and removeved again if necessary. Any way you do it, your're going to do some damage to a classic speaker. Chances are it is the caps that are defective, causing the tweeters to not funtion.

I myself would be interested in any other ideas of how to approach this problem.

Andy

[tysontom]

>Hello, this is my first post on this site so I hope I post in

>the right thread, KLH.

>

>I recently bought a pair of KLH Model Fours. The twin tweeters

>do not work in one of the speakers. From the research I've

>done It's most likely the caps, not the tweeters. Problem is

>the cabinets are completely sealed and the drivers are epoxied

>to the front baffle. I've managed to removed the grills

>without breaking them but that does me no good in accessing

>the caps. I know I can cut through the back but I'm wondering

>if carefully prying up the back plate will access the caps.

>Unless they are glued on the back of the front baffle?

>Suggestions welcome.

Archie,

As others have said, crossover capacitors are the bane of the early epoxied-in KLH speakers, such as the Model Four, Model Six and Model Seven. Ironically, the earliest versions of the Model Four and Six (and possibly some Sevens) used war-surplus oil-filled capacitors, and these versions perform flawlessly over the years. These capacitors probably will never fail, but who knows!

The way the factory repaired these speakers in the old Henry Kloss/KLH days was to remove the grill cloth and black-muslin (which destroyed them both, basically), "rip out" the old woofer cone and voice-coil assembly, and then make the necessary repairs through the woofer hole. A new cone was then re-attached (this was probably dicey even at the factory), and a new grill was affixed and the speaker was repaired and sent back to the owner. Only the factory could do this type of repair from all I have ever heard.

There is about no alternative other than to cut a hole in the back of the speaker to make the repair. A hole could also be cut in the front of the speaker the same way, and the grill cloth could then be permanently attached after the repair. The grill was originally glued down into slots around the perimeter of the front of the baffle board and was thus made "permanent." Some individuals have been able to knock the front baffle loose from the cabinet, but I would be afraid to try to do that for fear of damaging the rest of the cabinet. In most liklihood, the rest of the cabinet would have been destroyed in the process, so a hole in the back is probably the least traumatic means of gaining access to the crossover.

--Tom Tyson

[Guest archie]

I cut a hole in the back of the Four and pulled out the crossover. I see 5 resistors heavily glued to the back plate and 1 capacitor clamped off to the side. I don't see any inductor. the cap is a Syncro and reads 3 mfd. It looks like burnt orange in color with some brownish hard substance on the end the wires come out. Cabinet is dated June 1, 1964.

The cabinet is braced internally so if anyone else is going to try this, I wouldn't cut any higher than 1 foot from the bottom. Also I could have made a much smaller cut, about 1/2 inch from the metal back plate all around. But I had no idea where all the crossover parts were. And it may not be the same on all Model Fours.

[Andy]

Archie, Glad to hear your repair went well. From a historical standpoint, it's interesting to hear that The Model Four was still being produced in June of 1964 which must have been near the end of it's production - Singer bought KLH in '64 and many changes and new products came in 1965.

The Model four is a fine speaker, KLH's first full-range speaker, it was chosen by CBS records as their monitor speaker in about 1959-60. According to Kloss, it was "widely competitive with the AR-1, at $224. each."

You don't see that many Four's out ther today, good luck with yours.

Andy

[Guest archie]

Must be a later pair, serial numbers run in the low 6K.