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JayRd7

Model 20 black surround question

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Have a pair of Model 20s I’m restoring for a friend. The woofers have black surrounds - I’ve seen these on some eBay listings as well. Was this a factory thing, or a re-seal done at some point in time? Thanks for any help! 

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Maybe post a picture of the surround.

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The color looks normal to me. Hard to make out the texture though. The original butyl rubber coating left the weave of the fabric visible. It looks like yours "may" be smooth (?). In that case I'd suspect something like caulk may have been added. (that would be bad). Here are pics of 2 different Twenties I've worked on. Nice speakers. Remember to use an amp rated for 4 Ohms. btw, I put 5-way binding posts on both pair.

_kent

KLH20 woofer.JPG

KLH-20 4.JPG

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Very nice!! Thanks for the info as always, must have just been a different "flavor" out of the factory - the only ones I've worked on have been tan colored. It was interesting taking these ones apart and seeing some subtle differences between them and mine - back in the days where mostly everything was done by hand and not a fully automated assembly line. 

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Sorry. I was typing while you were. Check edited reply

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Ok good to know, I'll take a look when I get home and see what the texture is like and I'll try to post an up-close picture of it.

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Sometimes the butyl sealer used for the surrounds (and dust caps) contained lampblack, which results in the appearance you are asking about - - same was used on this pair of woofers in KLH Thirty-Two's.  

as found 4.jpg

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Thanks very much for the info ra.ra, I'm hoping that's what this is! Here is a more closeup photo. There does appear to be a couple of larger globs of this stuff here and there, hoping that doesn't make a difference - just want to be sure I can safely apply the AR vintage sealant stuff as I know these speakers haven't been touched in maybe 15-20 years. I also had a question about the voice coils - when I press down gently and evenly around the woofer, I hear some intermittent rubbing which concerns me. I pulled this cab apart before I even had the chance to test them. I did however do an ohm test and I'm getting a steady reading of 3.5 ohms on the woofer which I believe would indicate the voice coil is intact, but any suggestions about the rubbing? Thanks!

  IMG_7115.thumb.jpg.7d6c8d4747148d1537fd320b9773b411.jpg

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Jay

That close-up seems to show the fabric so my guess is there is no foreign sealant on there.

The sealant sold by Vintage AR was cooked up by RoyC and is the ONLY sealant that should be used. Brush on one thin coat. btw, I just looked at the Vintage AR ad it it says "This is only available in clear. The clear will reactivate the black color if the original was black". So there you have further verification that some surrounds had black sealant.

Sorry for the temporary monkey wrench I threw in the works.

Kent

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Perfect! Thanks for the clarification, and yes I ordered the genuine stuff off of eBay that I used for my restore a few months back. No worries on any monkey wrenches, better safe than sorry. Any ideas on the voice coils? Thanks again! -Jay

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As further confirmation, my KLH Twenties have black cloth surrounds. The surrounds look original with the cloth fibers visible. RoyC's doping solution soaked just like it should, so my speakers were not coated with another, unapproved compound.

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This comment is from a 2014 thread about AR speakers, but it basically applies here as well.

As for color, the original cloth surrounds were made from an orange-tinted cloth material, and with the butyl-latex (originals were not water-based) clear material applied, the surround looks orange or yellowish orange in appearance, which is 100% normal. Later, AR (and others) added lamp-black dye to the material to make the surrounds black and thus not be noticeable through the grill cloth. No real difference in performance, except that the early orange-colored surrounds seem to remain somewhat better sealed over time. Perhaps the lamp black causes the material to harden sooner.

—Tom Tyson

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