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KLH Model Seventeen Manufacture Date


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Welcome keenone. Nice speakers. I can't give  you an exact date but the Seventeens were manufactured 1965 - 1974 according to the table in our Library, or 1977 according to some other information. I think '77 is more likely. . Considered to be among KLH's best 2-ways.

I'd recommend replacing the crossover capacitors. If you haven't done it before, it's not hard but those old caps are notorious for going bad.

Kent

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Each speaker takes one 8uF cap and two 2uF caps. Partsexpress.com has them: https://www.parts-express.com/dayton-audio-dmpc-20-20uf-250v-polypropylene-capacitor--027-414 and https://www.parts-express.com/dayton-audio-dmpc-82-82uf-250v-polypropylene-capacitor--027-426  (8.2uF is close enough--well within tolerance) or if you want exactly 8.0uF, double up on these: https://www.parts-express.com/dayton-audio-dmpc-40-40uf-250v-polypropylene-capacitor--027-421

These are modern film caps, so not original to the speaker. Film caps last virtually forever but non-polar electrolytics (NPEs) like the originals last a couple of decades. Parts Express does have NPEs but most of us here use film  https://www.parts-express.com/cat/non-polarized-electrolytic-capacitors/1385

I should also mention, because it can be confusing, the 2uF caps in the original crossovers are double--two 2uF capacitors in a single case with one common (black) lead and 2 red leads. Just replace that with two 2uF caps. Also--don't worry about the voltage rating. I think the originals were 50VDC, modern caps will be higher. It's always good to go higher, never lower.

There is a way to check the caps but new ones are so cheap it's not worth it. 

Below is a schematic and a picture of a Model Seventeen crossover with an exploded capacitor.

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exploded.JPG

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wow, thank you for this info. So it sounds like it’s possible that my speakers could sound even better than they do now if I do this, but it will at least make them last longer, is that right?

I have not worked on anything like this before, but would I need to take the speakers out of the front to do this, or does the back panel come off? Honestly, I don’t even know how to take the front screens off which are in near perfect condition and I’m afraid to mess them up somehow. I assume I will need a soldering iron, is that correct?

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OK. A good introduction to speaker restoration is this: http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/  The AR-3a is bigger and more complex but some principles are common to all speakers of this era. Here's a thread on Seventeen restoration: https://community.classicspeakerpages.net/topic/11067-another-seventeen-restoration/  You can also search through this forum for Model Seventeen (or the essentially identical Model Twenty) restoration.

 

Your grilles are attached with Velcro, so they'll pull right off. Next remove the woofer by removing all the screws. There is putty sealing the woofer to the cabinet and it may have become rock hard so it could be tough to remove. Pull the woofer out and you'll see the 2 wires: red & black. These are connected with wire nuts. Remove the wire nuts.

There is a piece of crinoline-like cloth behind the woofer. This keeps fiberglass out of the woofer. Remove that and set it aside. Next, wearing gloves, pull out the fiberglass and store it in a plastic bag. This will reveal the crossover. 

What you want to remove is the 2 black capacitors with red ends. One, the 8uF is a single and you can just the 2 wires and splice in the new cap. You can solder it or use crimp connectors.

Now look at the double cap. It has a black wire coming out of one end and 2 red wires coming out of the other. Take your two 2uF caps and twist one lead from each together so you now have one lead at one end and two leads at the other. Use this to replace the double cap. Just make sure you locate the caps somewhere so the metal leads don't touch any other metal. 

Then put it all back together in reverse order. Make sure to get that crinoline in there to protect the woofer. And you will need a seal between the woofer and the cabinet (like the old putty). The best stuff is foam gasket from Parts Express. https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540  But you can also use duct seal, available from Lowes or Home Despot https://www.lowes.com/pd/Gardner-Bender-16-oz-Duct-Seal/4595233?cm_mmc=shp-_-c-_-prd-_-elc-_-google-_-lia-_-106-_-electricalaccessories-_-4595233-_-0&placeholder=null&&ds_a_cid=112741100&gclid=CjwKCAjwkoz7BRBPEiwAeKw3qyzqFfPAGbogQPlvT0WG693ZafxEHlZPiQxLfA5aaoc4s_6t4onK_RoC-_oQAvD_BwE&gclsrc=aw.ds  The idea is to make the speaker air-tight. After it's finished you may want to use Roy's sealant on the woofer surround, but that can wait.

Kent

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Thank you for this detailed info, I will order some parts and try this. Do you think a high quality silicon for windows and such, for example GE silicone would work to seal the woofers?

I’ve use this silicone on many things like my home’s sunroom glass panes, and have been blown away at how long it stays soft and leakproof even under direct sunlight, rain and weather...for years.

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I wouldn't. The foam gasket tape creates a good seal but the woofer can be removed easily if needed. The duct seal is less convenient but still lets you remove the woofer. You tear off a chunk and roll it out to make a snake like you may have done with plasticene "modeling clay" as a kid. GE Silicone will hold it tight and make it difficult to remove.

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On 9/16/2020 at 9:44 PM, keenone said:

I’m trying to figure out the manufacture year of these KLH speakers I purchased, which are in excellent condition:

https://sfbay.craigslist.org/nby/ele/d/el-verano-klh-speakers-vintage-model-17/7187257749.html

The serial numbers are 0096xx

Hey there, I've been meaning to ask you about something.

I believe I've seen a post you made some time ago that had some information regarding finding dates of manufacture and version of klh6 and possibly others?

I think that it was based on serial numbers.

Pardon me if I've asked you this before and don't remember your reply.

As always,

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Serial numbers were sequential, so there's no code. Some KLH drivers have manufacture dates stamped on them. I suppose if you knew the exact dates of manufacture (was it '65 to '74? '77?) and how many were made, you could sorta figure out the year. I do a lot of work on KLH Model Eight radios and I know they started making them in 1960 and there was a Rev A from May-Aug and that Rev B started "around" SN 1200 so maybe they made about 300 a month at that time (?). The Rev B went up to about SN 12000 and I "think" they stopped making them about 1964 (the Twenty-One replaced the Eight in 1965) so in 5 or so years they built about 10,000 or so Rev Bs, so maybe 2,000 a year. It's a lot of guesswork.

Third party manufacturers used EIA codes but KLH made their own drivers. CTS supplied many drivers for various companies so for example an EIA code of 137-6012 would mean CTS (137), 1960 (60) 12th week.

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On 9/20/2020 at 2:59 PM, Jim Pearce said:

Hey there, I've been meaning to ask you about something.

I believe I've seen a post you made some time ago that had some information regarding finding dates of manufacture and version of klh6 and possibly others?

I think that it was based on serial numbers.

Pardon me if I've asked you this before and don't remember your reply.

As always,

No, I just joined this forum and my only posts so far are in this thread.

Since my speakers are in the 9000 range it looks like they could be fairly early, possibly ‘65-‘67. I understand that when the company was sold in ‘67 they added letters in front and changed the serial number format.

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Sorry, I'm not very good at navigating this site as has been shown more than once.

My question about the date versus serial number reference chart was directed towards jk.

Although I really appreciate the information you have supplied I had no idea about any of that. I thought all of their drivers were made in house.

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53 minutes ago, Jim Pearce said:

Although I really appreciate the information you have supplied I had no idea about any of that. I thought all of their drivers were made in house.

Yes. AFAIK KLH made all their own drivers 

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I just started working on a set of KLH Model 17 speakers and came across these two stamps inside one if the cabinets. Just wondering if the codes could represent dates.

I’ve worked on Model 17’s before but don’t remember seeing a stamp like this. 

Is it s random code or a date of manufacture?

36F4B988-5F69-4A8B-85BA-77B7DEC79B7D.jpeg

ECA68856-0F85-4F62-BC1D-BCD7D64C1989.jpeg

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Here’s a couple of questions related to the Model 17 but not directly on topic to this thread. I do not mean to hijack the thread, but I thought people who are interested in Model 17 speakers would be a good place to start.

the Model 17 set that I am currently restoring seems to have less fiberglass insulation inside the cabinet than any other KLH or Advent speaker I have ever worked on.

1. How important is the insulation to the performance of the speaker?

2. Should I think of replacing or augmenting the current insulation?

Any input would be appreciated.

Thanks!.

PS: the second Model 17 cabinet I am now working on has a similar stamp inside the cabinet just like photos I posted previously, but this one has only one stamp, not two.

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