Picked up a pair of KLH Model 20's at an estate sale last weekend...

[Treker]

I recapped my KLH Model 20s this evening, and all I can say is "WOW!" What a difference!

I recapped one speaker first and then did an A/B comparison between them. The different was incredibly dramatic! The highs had returned to the recapped speaker, and were almost totally absent in the un-recapped speaker. I then rushed to recap the other speaker in order to be able to listen to them as a pair. For those that are interested, I used Dayton caps purchased from Parts Express. This was also my very first speaker recap.

I am currently listening to Dire Straits On Every Street on CD, and these speakers sound very nice. As it is late in the evening, I haven't really had a chance to turn them up, but at my normal listening volume, I'd have to say they sound very good. I am planning on redoping the cloth surrounds with the material I purchased from RoyC over on the Classic Speaker Pages web site in the next couple of days. I also plan to do another A/B test to see just how much of a difference the redoping makes in the bass response of these speakers. I'll report back again when I have that completed.

 

[gbroot]

I have treated the surrounds on my 23's, 5's, & 22's with the compound that vintage AR on ebay sells. You will notice a marked increase in bass response. With the recap + redope the 20's should be good to go for a long time. FYI, the 20's are a 4 ohm version of the 17's which I have in my office. However, if you have a chance to hear 23's or 5's, the 20's will be in your rear view mirror.

 

[Dingman]

I recapped my KLH Model 20s this evening, and all I can say is "WOW!" What a difference!

I recapped one speaker first and then did an A/B comparison between them. The different was incredibly dramatic! The highs had returned to the recapped speaker, and were almost totally absent in the un-recapped speaker. I then rushed to recap the other speaker in order to be able to listen to them as a pair. For those that are interested, I used Dayton caps purchased from Parts Express. This was also my very first speaker recap.

I am currently listening to Dire Straits On Every Street on CD, and these speakers sound very nice. As it is late in the evening, I haven't really had a chance to turn them up, but at my normal listening volume, I'd have to say they sound very good. I am planning on redoping the cloth surrounds with the material I purchased from RoyC over on the Classic Speaker Pages web site in the next couple of days. I also plan to do another A/B test to see just how much of a difference the redoping makes in the bass response of these speakers. I'll report back again when I have that completed.

I also have a set of 20's that I've recapped, and I agree that they sound very, very nice. I really like them with a Marantz 2270 (far better than a Pioneer silver something).

I haven't looked at re-doping - thanks for the info here, I'll order some of that stuff up!

 

[HSAH]

My article on the model twenty & the first generation KLH phono systems.

http://www.antiqueradio.com/Mar06_Hayden_Kloss.html

And to confirm, no badges on the grills. Folks often think they do because the sister speaker, the model seventeen does have badges. The model twenty plus is mixed...seen many with badges and examples with no sign of ever having them.

 

[Treker]

I have treated the surrounds on my 23's, 5's, & 22's with the compound that vintage AR on ebay sells. You will notice a marked increase in bass response. With the recap + redope the 20's should be good to go for a long time. FYI, the 20's are a 4 ohm version of the 17's which I have in my office. However, if you have a chance to hear 23's or 5's, the 20's will be in your rear view mirror.

Thanks for the tip. I'll certainly keep my eyes open for a pair of 23s. I have only come across 2 pairs of vintage KLH speakers since I got into the hobby, a pair of 17s, which I passsed on at the time, and this pair of 20s that I have. I suspect that the larger models are a bit more rare being that they were more expensive back in the day, but hopefully some will come across my path someday.

 

[gbroot]

23's and 5's show up on "the auction" site fairly often. That is where I got mine. Both for around a C note + shipping. You would also like model 6's. Slightly larger cabinet than the 20's, 17's and slightly larger woofer, bass is closer to the 23's & 5's. Same tweet and crossover as the 17's.

 

[Treker]

Here is a pic of the crossover network in the KLH Model 20 before recapping. The original caps were the following:

SYNCRO EP25263
RED 2 X 2 MFD 50VNP
BLK COM NEG
10816508

SYNCRO EP25257
RED 2 X 4 MFD 50VNP
BLK COM NEG
10816508

And here is the after pic. I used hot glue to fasten the new caps down. I covered the leads on the new caps with heat shrink tubing before installation. I also just cut the leads off the cap that was originally mounted on the aluminum crossover plate, and then used wire nuts to fasten the new caps to the remaining wires. It was a lot easier than trying to maneuver a hot soldering iron around inside the speaker cabinet.

I used the following new new caps from Parts Express:

027-414 Dayton DMPC-2.0 2.0uf-250V PO ... Qty 4
027-421 Dayton DMPC-4.0 4.0uf-250V PO ... Qty 4

These caps are quite inexpensive at around $2 each or less.

 

[gbroot]

Great job! same exact recap as the model 6's. The Model 5's were a little more complicated as they are a three way. However, believe it or not as fine sounding as the 23's are..The crossovers are very simple..a 4uf per cabinet. I have used dayton 1% and 5% and really don't hear any difference.

 

[skandl]

:thmbsp:

Well, they sounded very muddy, lacking in both the lows and the highs. That's why I assumed a recapping would be in order to restore the highs, and a redoping of the woffer surrounds would probably be necessary to restore the low end. I just want to go about the redoping the right way.

However, I have read about several different products being used for redoping old cloth surrounds, I was just wondering if there is a current consensus as to what is the best product to use in order to restore the surrounds to as close to their original factory condition as possible, as well as restoring them for longevity and long term performance. Any input would be greatly appreciated.

+1 Recap

Same problem with my neighbors 5's muddy and lacking mids/highs. Recapped both x-overs for him and WOW:thmbsp:

 

[Treker]

Well, I completed the restoration of my KLH Model 20 speakers and started listening to them today. But before I give my impressions of how they sound after the restoration, here are a few pics.

As stated earlier, I purchased some of the doping compound that RoyC over at the Classic Speaker Pages web site formulated especially for the cloth surrounds of the KLH and AR speakers. It cost me $15 including shipping. These first couple of pictures are of the woofer and surround before application of the doping compound.

And here are some pics after application of the doping compound.

You will notice some bleed through in the last photo in some areas, but not in others. This is just where the original doping compound had worn out and was allowing air through the cloth surround.

When doing a woofer compression test after the re-doping, it was very apparent that they rebounded more slowly than before re-doping.

As with the recap, I did an A/B listening test between the one speaker in which I had re-doped the woofer, and the one in which I had not. There was a subtle improvement in the bass response of the re-doped speaker, but nothing like the total transformation that took place after the new caps were installed. It was definitely an improvement though.

And here are a few pics of the completed speakers. Because these speakers were in such good condition to begin with, they don't look a whole lot different than when I first brought them home. I did apply a coating of Howard Feed-N-Wax to the cabinets, and it did brighten them up quite a bit though.

My goal with this project was to restore these speakers back to as close to their original condition as I could, both appearance wise and sound wise. Since it is impossible to time travel and compare my restored pair to a brand new production pair, it is really impossible to tell if I was 100% successful in that endeavor, but I am pretty pleased with the way they turned out. They now sound very good to my ears, and look very nice as well. I'm pretty impressed that a nearly 50 year old speaker sounds this good. I think I am going to keep them around for a while.