KLH Model 5 Crossover Information

[administrator]

Thanks to Carl, The SpeakerDoctor, who drew up some schematics for the KLH Model 5 as he was upgrading caps. Carl also took a picture of the crossover.

Check it out in the KLH section.

Mark

[Guest Hoffman Tenor]

Are there any good "How -to" references available to help with this crossover repair or replacement? I recently acquired a pair of KLH Model 5's, and one of the speakers seems to be having similar issues with the crossover (no signal going to the tweeter). I've never worked "under the hood" of speakers before, but I would love to get these working properly.

Any tips or advice from the forum is appreciated.

THanks,

[mrdb]

You must remove the woofer to gain access to the crossover. Remove the stuffing (use a mask and gloves). You'll also need to remove the nuts under the input binding posts on the back. The crossover is secured to the inside of the cabinet with four screws. Disconnect the speaker leads. Note the wiring colors and destinations before removing the wirenuts. The crossover should now be removable. Be careful to save the fiber insulating washer(s) on the input terminal posts. My Fives had no tweeter output from either cabinet. The same dual-section capacitor was bad in each. I replaced them all with polypropylenes. Check the condition of the ground connections at the terminal strips. They supply ground interconnections and were loose/oxidized on both of my crossovers. If you are not experienced or comfortable with replacing the parts, check with a local service shop. It shouldn't be too expensive to have the caps replaced and the ground terminals interconnected. By the way, this info is for the crossover assembly as shown in my photo in the KLH section. I have another crossover assembly that is printed circuit based, probably a later version. The circuit appears identical but the inductors are of a different type.

Check your surrounds for air leakage. They are treated cloth and probably need to be recoated. I tried some diluted glue recommended by Stephen at Layne Audio, but the surrounds are leaking air again after a year.

Lord industries makes a coating but it is expensive and evidently only available in gallon cans.

The midranges also need to be treated. They are in a sub-enclosure and are air-suspension. Check for a seal where the wires enter the sub-enclosure. Reseal with RTV if necessary.

See my write-up in the KLH section for the rebuild history.

By the way, I like these speakers a lot.

Bob

[mrdb]

I forgot to mention that my previous post assumes that the tweeter itself is not defective. You can test this with an ohmmeter for continuity and operationally by hooking the tweeter in series with a 5 microfarad capacitor to the output of an amplifier played at low volume. Don't forego the cap or you might burn out a good tweeter with too much low frequency energy.

Bob

[Guest rickcee]

That's an excel. write up of speaker fix. ( KLH 5 )

On my old KLH 17, same type cloth surround ( maybe even same woofers ? ) I sealed the cloth with 2 thin coats of rubber cement. NOT contact glue. The rubber cement for Kids projects. This was several years ago, still seems fine, but no guarantees.

enjoy Rick

[mrdb]

This is an update to my KLH Five restoration of a year ago:

The glue mixture that I used on the woofer and midrange surrounds(Aleene's Tacky Glue cut four-to-one with water)has caused the

surrounds to stiffen enough so that the woofer resonance in the cabinet is around 65Hz. I don't know what the original specification was but I assume that it should be around 40Hz (similar to AR). When I wet the surround with water, the system resonance drops to 45Hz and the Q seems lower. I'm going to try to remove some of the glue and try a butyl rubber coating. I'll update at that point.

In the meantime, be careful with what gets applied to cloth surrounds.

Bob

[Guest klhfive]

Hi,

About 18 years ago I bought a used pair of KLH fives in nice condition at a swap meet in Tucson. Recently I made the mistake of unplugging an RCA signal cable to the input of the amplifier and touched with my finger the hot input signal. My body served as a 60 hertz antenna sending a strong signal to the amplifier and then one of my woofers in the KLH fives just blew out. Tough lesson. I bought from ebay another but earlier pair of KLH fives with the same dual cap problem described in Bob's write up (this is a very nice write up) and also used Alene’s glue to seal the woofers. I also measured the frequency response with Speaker Workshop before and after. I am no expert in making measurements though I believe are fairly good. Attached are four measurement for a KLH model five, the near and far field frequency curves, and two near field before and after using Alene’s glue. It seems that the glue increases the frequency bump around 50-100 hertz jus a bit. Perhaps the major thing about sealing the surround is to help prevent deconing the drivers. The crossovers are, I think, complex and on my first pair of KLH fives, that are newer, the crossovers are in a printed circuit. Recently in a swap meet I bought a third pair of KLH fives for five dollars! So I will focus in having two sets in good working condition. I like to thank Bob for posting his suggestions for KLH and to Mark for his excellent web site. Jose Sasian (It seems that I can't upload the measurement files. I will be happy to email them).

[soundminded]

Thank you Carl for the fine job you did with the KLH 5 crossover network.

I have always found it fascinating that the midrange control actually affects the tweeter's frequency response and not the midrange drivers' level or response. Henry Kloss once said in a published interview that after KLH-6, he would always include equalization in his crossover designs.