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KLH model #12


82nd-EOD
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Hi, I am trying to find what is the truth as to what drivers are used in the KLH model #12's?  I have a one set that has been rebuilt, And sound GREAT. A second set I just found for next to nothing, One of the woofers has been replaced with a newer 12 inch KLH driver. So now I am looking for a #12 woofer. I have people that say the drivers are the same as the #5, I have also other people that say the #5 and #12 are not interchangeable? After looking at the drivers I found that the tweeters for the #12 have M12 stamped in the front of the basket, Need to look close but they are on the model#12 tweeters the model #5 tweeters are not marked. The mids look the same on the #12 and #5. The woofers look the same except the ones in the model#12 are marked with a 12 and 24.6 or 26.6 in marker on the cone, The model #5 has no marks on them. GetAttachmentThumbnail?id=AQMkADAwATcwMAItODBiMS1mODQwLTAwAi0wMAoARgAAAxNsBhkS7t5BodQdtUw6Ly4HAJPUSkMdmNNInRerEsKvhnoAAAIBDAAAAJPUSkMdmNNInRerEsKvhnoABDFMZu4AAAABEgAQAG0zgJ3h9uhLknPNgQmx844%3D&thumbnailType=2&isc=1&token=eyJhbGciOiJSUzI1NiIsImtpZCI6IjMwODE3OUNFNUY0QjUyRTc4QjJEQjg5NjZCQUY0RUNDMzcyN0FFRUUiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJNSUY1emw5TFV1ZUxMYmlXYTY5T3pEY25ydTQifQ.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.i26EpFe0fEVjOg64smjBzUivpCGPbsJjIri_8pdb-0ijO9PvtRSrt130Gbn-4ncCufWXKZaSGULvqDbpzXLpqn5eOn7xO5jUWwlzE-2obJbirytUZWLm9f9quO5lx4h66rLy90mqS3zR4D1aLOIsudI3POdXck8Ck_LGrqZwRIwjFi52k3MrLpmxgoQni6xMhYrflYtXxGqw_U4MyZdW3-mWv4HT6JU8tKkBOphwAoG8yio43KeA2Whx1giWx8fyKOJuiIgtSAh4S6Gs9qfB7_Cg4H0-BDr05LRZv5BUeVjoZRdvCq-W_AxxrGx1ao0urunxwNcz5BlKXAWeg8e_QA&X-OWA-CANARY=9XN96VJuX0evhuT36R9bZvBy3xrW-9gYlkbfJw5SvBQpbsaL5I-XXv5s9uwJ_nlY_AoKom4xtDA.&owa=outlook.live.com&scriptVer=20210405005.04&animation=true

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Welcome 82nd

I'm a fan of the Fives and Twelves and although I've restored a couple and recapped many I don't have any right now. KLH always spelled the model numbers out but let's use shorthand and call them 5 and 12. The driver question has been kicking around fo a long time and has not been fully resolved IMHO.

Let's start with the mids because that's easy: They're the same. KLH called their 4" full-range driver the "Twelve point five" (no idea why) and started using it in the Model Eight tube radio when they ran out of 3" drivers. It was used as a mid in the 5 and 12 and as a full-range in the later 8, 13, 14, 15, 19, all 5 versions of the 21 radio and a few compact systems.

The tweeters all look the same, with metal grilles, but some are painted black. That's not the difference. Model 5, 12, and 23 have a thin top plate above the magnet, all others have the same thickness plates above and below the magnet. The M12 tweeter was used in the Model Twelve. But in real world application it probably doesn't matter as long as the pair matches. This very long thread may give some clues about the difference. The thickness thing is hard to spot unless you compare them side by side. Color does NOT matter. https://www.audiokarma.org/forums/index.php?threads/klh-tweeter-id-and-repair.492609/

The 12" woofer: Of course it's not really 12" but that's what they called it. More like 10.75" Some 5s had woofers with square magnets and I have no first hand experience with those but they are not for the Model 12. Other Model 5s had round magnets, as did the Model 12 but the Model 12 woofer's magnet is about twice as thick. So no--they're not the same. There is a knowledgeable member on Audio Karma who claims later Model Twelves did use the same round magnet woofer as the Five. I have no way of confirming this but I do think that so long as the woofers match in any given pair of speakers it "may" not be a big deal.

The markings in ink on the woofer cones are test measurements from the factory. I forget what they measured--mass or something.

Check out this thread: 

btw--We like pictures but yours isn't showing up. Maybe too big. Resize jpg images to about 100kb or so.

Kent

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One last comment (for now): Check out this KLH Service Bulletin http://www.classicspeakerpages.net/library/klh/other/klh_schematicsservice/klh_service_bulletin_60.pdf  Re-sealing the cloth surrounds on KLH woofers can make a HUGE difference. Our RoyC makes the ONLY sealer you should ever use and it's sold by ebay seller Vintage-AR. Experience has shown that it's helpful on some AR woofers but not necessarily all (the AR-4 for example benefits little) but I can tell you it turns a KLH Model Five from a pretty good speaker into a great one.

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  • 3 months later...

I'm going to hijack this thread for my latest KLH Model Twelve project. A fellow CSP member picked up a very nice pair and will be doing the cosmetic work himself but he sent me the contour boxes to rebuild. I'll let him chime in if he chooses to.

He reported that one box was dead in the midrange. I've ordered new capacitors and resistors and am waiting for delivery but decided to tear apart the dead crossover while waiting. I tested the woofer, mid and tweeter outputs by connecting a full-range driver to the woofer and mid outputs and a tweeter to the tweet and found that the woofer output was OK but the mid and tweet were very weak.

Pulled all the caps. Some were doubles but wired in parallel. I was amazed this crossover worked at all, given the readings. I even replaced the battery in my Capacitance meter and checked it on a new capacitor. So here are the readings:

Marked    Reading

3 MFD        0.02
2x2 MFD    .001
                   .001
2x4 MF     .002
                   .002
2x4 MFD    .001
                   .002
2x4 MFD    1.02
                   0.62
50 MFD      2.9
50 MFD      4.4    

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The 2nd xo's caps weren't nearly as bad. Mostly off by 20-25% although one 2x4uF measured 0.18 and 0.13, and the 50uFs both measured in the 70s. 

I've mentioned this many times--I always replace the 5w resistors in these crossovers with 10w. Second photo below shows a resistor I found in a Model Twelve years ago. There are 7 resistors per box and at two bits each (Erse) it's cheap insurance: 2 15ohm, 2 10 ohm, 2 6ohm and 1 5ohm per contour box.

Caps used this time were mostly from Erse: 2 50uF NPEs per box. The rest are all mylar: one 16uF mylar, three 4uF and one 3uF (a TI that I happened to have on hand).

Tested the finished boxes with a full-range driver to make sure everything worked and they're both now loud & clear, ready to return to the owner.

completed xo3.jpg

burned 5w.jpg

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19 hours ago, JKent said:

Caps used this time were mostly from Erse: 2 50uF NPEs per box. The rest are all mylar: one 16uF mylar, three 4uF and one 3uF (a TI that I happened to have on hand).

Nice work as usual, Kent. I typically don't comment on capacitors, but I would avoid Erse npe's in the future. Relatively recent measurements show them to be inconsistent, and never as good as their physically larger counterparts sold by Parts Express and Madisound (MDL brand). Erse mylar caps continue to be an excellent value.

Roy

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  • 2 months later...
  • 1 month later...

Sorry. I have never seen a schematic for the Model Twelve and it is certainly not needed for replacing caps and resistors. I do recommend replacing the 5watt resistors with 10 watt.

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  • 1 month later...

Hey guys !

My name is Zbigniew and I am from Poland.I have bought these wonderful speakers.

They have beautiful chests,and fantastic sound.They are very rare in Poland, I waited six months for a friend to sell them to me.

So far, I have listened to the model five,very good sound too, but that's not it

Now I am getting on with the renewal of these speakers,

I saw that the potentiometers are disconnected, I asked my friend what was going on( I attach photos),

says he made them for a permanently flat sound,

I'd like to go back to the original and be able to adjust the sound relative to my room.

i watched all the photos on this forum but it's hard to see all the capacitor connections.

maybe someone make a freehand drawing of what and how to connect ??

the capacitors used in one case are:

2x3,9

1x15

1x47

Thank you in advance for your help and best regards from Poland

crossover 1.jpg

crossover 2.jpg

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Oh dear! Great speakers but your friend made a mess. I've worked on a lot of these contour boxes and they are very complex. I've never found a schematic and I'm afraid you will never be able to re-wire everything correctly. You could watch ebay to see if some contour boxes come up for sale. That happens once in a great while. In the meantime the only thing I could suggest is that you try using a separate equalizer.

Kent

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Hi Kent thanks for the reply

I have been looking for and watching ebay for quite some time in search of these crossover boxes.

I know I know freehand drawing of connections is difficult and laborious

I will think about using an external graphic equalizer.

Best wishes Zbigniew 

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7 hours ago, Zbigniew59 said:

I know freehand drawing of connections is difficult and laborious

and unfortunately I don't have any Model Twelve boxes to look at. I sold mine and have restored some for others but I have none here.

Model Five crossovers "should" work but they won' give the flexibility of the Contour boxes (or an EQ). Good luck.

Kent

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