Not 1 but 4 KLH Model Six! Any advice on fixing up?

[GD70]

Thanks Glenn, Yes but I don't think I saw how to fix damage into the MDF.
If a big chunk of MDF is missing would you fill it with the walnut sanding mixed
with Z-Poxy? I guess for MDF patches I could mix with regular sawdust?
Picture of the damage:
https://audiokarma.org/forums/index.php?attachments/100_1599-jpg.2622369/

More here in post #2:
https://audiokarma.org/forums/index.php?threads/new-large-advents-nla-with-water-damage.1002674/

Hi Pete,

After I glue in the veneer patches, I then fill the cavity with ZPoxy, level with the back surface. The particle board will absorb some of it, so keep adding more a little at a time until it stops absorbing the poxy.

 

[Pete B]

Nice work! And I don't hear from people often who've built the BSC thanks for the feedback!

I don't work on KLH speakers much, but I'd think that the holes are quite small
and would expect that one coat should do it.
Very small leaks do not harm the response, in fact AR deliberately had very small
ones to equalize the pressure inside and out. I'd ask Roy or one of our KLH experts.

 

[Pete B]

As for an update on the KLH, I've posted some update photos below, my goal right now is function over fashion and trying to bring them back from the grave, once I've done that then i'l tackle cleaning them up. I've used wood JB Weld epoxy sticks to seal all of the comers that are coming apart, which looks messy as hell but my goal is to get them sealed and then deal with making them look pretty. Then on the inside of each speaker I used PL premium adhesive to seal the corners and any cracks that I saw, which was challenging because you can't fit a caulk gun into the cabinets so I had to resort to finger panting some of the corners, but it got the job done. I let it dry and air out for about 3 days, used mortite rope caulk to seal the woofer back to the cabinet, two layers in front of the screw and one behind the screw. I've replaced all the caps in all four, found two resisters broken off which I fixed, I also did discover that one of the tweeters had the voice coil copper broken but my crappy soldering skills wasn't enough to reconnect them so I ended up buying a KLH 20 tweeter from ebay. Now all four speakers are working!
....

They sound great so far, but I feel that the advents have more bass? I'm going todo an A/B comparison with my OLA later to confirm. But still this makes me question if I need more sealant or I have a leak somewhere.

Henry's goal with the Large Advent was to match the low end of the AR-3a and both have
a low 40s woofer in box resonance. I've never seen official specs for the woofer in box
resonance (Fc) for any of the KLH systems but I seem to remember one that was 52 ish.
I would not be surprised if the LA s go a bit lower than the 23.

If anyone knows of KLH reviews that include input impedance we could figure out the Fc values.

About the way you fixed the boxes, that's exactly how I'd do it for a quick fix and to avoid
having them go to recycling. It is the bottom after all.

 

[Pete B]

Hi Pete,

After I glue in the veneer patches, I then fill the cavity with ZPoxy, level with the back surface. The particle board will absorb some of it, so keep adding more a little at a time until it stops absorbing the poxy.

Thanks Glenn, I'll give that a try.

 

[Mr_Mustrd]

Nice work! And I don't hear from people often who've built the BSC thanks for the feedback!

I don't work on KLH speakers much, but I'd think that the holes are quite small
and would expect that one coat should do it.
Very small leaks do not harm the response, in fact AR deliberately had very small
ones to equalize the pressure inside and out. I'd ask Roy or one of our KLH experts.

Thank you! I had a lot of fun putting it together and I got a kick out of my wifes reaction when I showed it to her, she basically just looked at and said, I don't know what I'm looking at. haha But now I can't listen to the advents without it. I did play the KLH through the BSC and the bass is more pronounced with the highs backed off just like the advents and I'm torn on which sounds better with the BSC or without, either way they both sound great.

I do think i'l need a second coat on the woofers, but for right now I'm just going to enjoy the fruits of my labor for a bit before I put on another coat. Thanks for the input! Great to talk with you after reading your threads for so long when I was researching the advents, your past threads have really helped me make the right decisions and not ruin a piece of history because of my ignorance.

 

[ceylon]

congradulations on an excellent find. i hope they give you many many years of gooooood listenin.

 

[Mr_Mustrd]

Your testing technique is fine. That seems to be a bit quick fo the cone to return. Did you seal the dust cap? See KLH Service Bulletin 60 about coating the surround (skivver) and the dust cap.

Applying two coats of sealant will not ruin the woofers, provided you are using the correct butyl compound from RoyC or vintage-ar. Just make sure you are applying a thin, even coat to both the surround and the dust cap. I've applied two coats to most of my KLH speakers. Before doping, the cloth was dry and I could easily see through the weave of the cloth. More than a year later, the surrounds are still tacky and they sound great.

Thank you! Yes I did seal the dust cap. I think I will add a 2nd coat. The jar I bought from vintage AR says it should be good for 2 to 4 and I'm halfway through it.

congradulations on an excellent find. i hope they give you many many years of gooooood listenin.

Thank you! Hopefully they'll last another 40 years!

 

[jimbofish]

I do think i'l need a second coat on the woofers, but for right now I'm just going to enjoy the fruits of my labor for a bit before I put on another coat.

That jar of sealer has a limited shelf life, so don't wait too long, or forget like I did. It gets gummy and unspreadable.

 

[drumbum]

That jar of sealer has a limited shelf life, so don't wait too long, or forget like I did. It gets gummy and unspreadable.

Thin with toluene.

 

[glend123]

I have 3 pairs of KLH speakers and they all needed 2 coats. I think one of them really needs 3 coats, but I put it on pretty thin.

 

[hornbostel]

Henry's goal with the Large Advent was to match the low end of the AR-3a and both have
a low 40s woofer in box resonance. I've never seen official specs for the woofer in box
resonance (Fc) for any of the KLH systems but I seem to remember one that was 52 ish.
I would not be surprised if the LA s go a bit lower than the 23.

If anyone knows of KLH reviews that include input impedance we could figure out the Fc values.

About the way you fixed the boxes, that's exactly how I'd do it for a quick fix and to avoid
having them go to recycling. It is the bottom after all.

I have a couple pairs of OLAs, fully restored. Also KLH 6 and 23s. I haven’t made measurements but i think it’s obvious IMHO that the KLH 23s punch lower than the OLAs. The 23s are pretty darn good. My 23s and 6s are in regular use in my front room and home office, respectively. OLAs are in the closet. Recently posted some observations with the OLAs stacked. Damn fine. Went head to head with my ADS L1230s and JBL L100ts. Pretty amazing.