Recently purchased a pair of KLH Model 6 speakers

[Norman Nicolai]

I just purchased a pair of KLH Model 6 speakers and need some advice. Photos are attached.

My observations and questions:

1. The tweeter on one of the speakers does not work. Originally, I thought the crossover was responsible, but it looks like the caps in the crossover were replaced. Do they look like the correct caps? 

2. I connected the non-working tweeter to an amplifier and it's definitely dead. Photo attached. Are the 1.75 " tweeters in the KLH models 5, 6, 17, and 20 identical? I have read that they are but wanted other opinions. I'm going to shop for a replacement on eBay. Any other sites good for this?

4. The woofers are in good shape but it looks like they are a bit dry and need to be re-apoxied. Any opinions from the photo attached?

5. The drivers were not sealed very well in the cabinets. The cabinets are in good shape externally. But I doubt that they were air tight. I'm planning on using electricians putty to get a good seal on the drivers and hot glue the inside edges of the cabinets and the back panel to get a good seal. Any other suggestions on how to accomplish this?

Thanks, and would appreciate any other feedback!

[JKent]

Hi Norman

I've never worked on a Six, so take this from whence it comes. 

1. That 8 uF cap "may" be a replacement but it's an electrolytic and I'd replace it with film. The 2 x 2uF Temple is original and is probably bad. This post shows the xo. You need two 2uF and one 8uF per speaker http://www.classicspeakerpages.net/IP.Board/index.php?/topic/8228-klh-model-6-restoration-xo-double-check-please-help/

Also see the Model Six manual for a schematic http://www.classicspeakerpages.net/library/klh/klh_6_klh_model_six/klh_6_manual/klh_6_manual_pg1.html#previous-photo

2. I'm pretty sure if the tweeter looks like yours it's OK. KLH tended to use the same tweets in several models.

4.

4 hours ago, Norman Nicolai said:

The woofers are in good shape but it looks like they are a bit dry and need to be re-apoxied. Any opinions from the photo attached?

I'm not sure what you mean. The cloth surrounds will benefit from a coating of Roy's butyl sealant, available from ebay seller Vintage_AR. https://www.ebay.com/itm/ACOUSTIC-RESEARCH-SPEAKER-CLOTH-SURROUND-WOOFER-SEALANT-KIT-ALSO-KLH/193001721613?hash=item2cefcc8f0d:g:aUQAAOxy7rdREiMo  See the KLH Service Bulletin #60 http://www.classicspeakerpages.net/library/klh/other/klh_schematicsservice/klh_service_bulletin_60.pdf

5. Duct seal (used by electricians) works well to make a seal between the drivers and cabinet. https://www.lowes.com/pd/Gardner-Bender-16-oz-Duct-Seal/4595233

Hope this is helpful.

Kent

 

[Norman Nicolai]

Thanks, Kent. I appreciate your input.

I misspoke on the "epoxy". I meant to say butyl and already have some on order from the same eBay vendor on your link.

I am totally inexperienced with restoring speakers and the caps looked kind of new to me, so I'm glad to have someone else look at them. I'm planning on replacing them with caps from PE after getting your opinion.

This question shows my inexperience: Are caps directional, that is, do they have to be inserted into the wiring in a specific way; is there a (+) and a (-) side? If so, are they labeled?

I have carefully labeled everything I have removed from the crossover. With my limited experience, both the photo links and the wiring schematic will be a big help.

Thanks, again.

NN

[JKent]

You're on the right track. That butyl sealant was cooked up by CSP member RoyC and is the only thing you should use on cloth surrounds.

Your question about caps is a good one. Electrolytic capacitors ARE normally directional but speakers use non-directional caps. The electrolytics in your speakers are called "NPE" for non-polar electrolytic. You can replace them with NPEs but you are better off using film caps, which are always non-polarized. Electrolytics go bad in 2 or 3 or 4 decades while film caps last virtually forever. The Temple NPE in your crossover is notorious for leaking.

Here's another capacitor weirdness: Old speakers often used dual value caps. That Temple marked "red 2x2uF" is a double. It has a common black lead and 2 rd leads. Replace it with two 2uF capacitors. Your new caps should be the same value in microfarads (uF or mfd) within 10%. That is, you can use a 2.2uF for the 2uF. The voltage rating should be equal to or greater than the originals. Your original NPEs are 50v, replacement film caps will be much higher.

 These are a good choice for the 2uF    https://www.parts-express.com/dayton-audio-dmpc-20-20uf-250v-polypropylene-capacitor--027-414

These will work for the 8 https://www.parts-express.com/dayton-audio-dmpc-82-82uf-250v-polypropylene-capacitor--027-426

While you're ordering (if you go with PE) you might consider a roll of this https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540  to use instead of the duct seal. There's a lot in a roll but you may get the vintage speaker restoration bug and buy more speakers ? The foam gasket tape makes it easier to remove the drivers in the future if you need to but duct seal works perfectly well. In fact, PE sells it in ready-formed "worms" https://www.parts-express.com/parts-express-12-speaker-sealing-caulk-box-of-72-pcs--260-400

I think you'll be very happy with the Sixes. Henry Kloss said he "got it right" with those. And you're lucky you didn't get the ones with the epoxied-in drivers. Those are a nightmare.

Good luck, ask any questions and post pictures.

-Kent

 

[Norman Nicolai]

Kent, thanks so much for all your help, especially the links to specific items on the Parts Express website. Having a link to a specific item is a huge help!

So this is where I am:

1. I found a replacement tweeter on eBay and won the auction. I will have the item in a week.

2. The caps and sealing material were ordered today on Parts Express.

3. The Butyl sealer was already ordered on eBay.

With the speakers removed I've started to work on refinishing the cabinets. All the parts on order should start to arrive by the time the cabinets are refinished.

Thanks, again. You probably saved me a great deal of time and prevented me from making more than a few errors, even though I've been researching this online for the last few weeks!

When the project is done I'll post photos of the finished product. Yeah, I think I now officially have the vintage speaker "bug" and will take on new projects in the future. I've always had an affinity for KLH products. One of my first "HiFi" purchases was a set of KLH Model 20's back in 1971 just before I set off for college. Getting a pair of Model 5's or 6's was something I always wanted. The Model 6's should pair well with the rest of my restored vintage equipment, a Fisher 500B receiver and an AR-Xa turntable.

[Norman Nicolai]

My KLH Model 6 restoration project is nearly finished. The only thing left is to replace the speaker grille with a porous off-white linen fabric, and then I will post some before and after photos. Most original Model 6's I have seen have had a dark brown fabric grille cover, and that is what came with these speakers. But the original fabric was worn and frayed, and I think that an off-white cloth will pair better with the Walnut finished cabinet.

The speakers sound terrific, but I have hit a bit of a glitch: Every now and then, one speaker seems to almost cut out, and the volume goes way down. If I jiggle the 3-position tweeter crossover switch on the back it returns to full volume, but that does not prevent the problem from recurring in an hour, or so. 

Can I spray some Deoxit into the switch from the back, or will that damage something? If the Deoxit can't be used I may have to remove the woofer and reopen the cabinet to troubleshoot this. I wound rather not do that. I don't want to take the speakers apart again if I can help it.

Overall, when the speakers are working, they sound great! They remind me of the Model 20's I had many years ago, only richer and with more bass. Right now they are paired to a comepletely refurbished Sherwood S8000IV Receiver that I picked up last week.