KLH Model Six Restore

[LorneG]

I've been looking for a pair of these for a while and have walked away from a couple opportunities to buy because of driver issues: non-original tweeters or bad sealant on the woofers.  I'm pairing these with a restored 1961 HH Scott 299-B, which I am now the third owner, and a 1963 AR XA turntable that I restored, which I am the second owner.  The Scott amp needs efficient speakers at only 21 wpc, but I'm playing this set-up in a small/medium size family room, so the Sixes, which arr very efficient, should be a good match.  Klipsch are typically recommended with 299-Bs but are too big for my space, and I like keeping the geography and lineage together.

I'm glad I was patient and was very happy to find these 45 minutes away at an estate sale company.  The drivers all work and the sides of the cabinets are in good shape, but not the tops.  Those have some bad water staining and scratches.  So question to the cabinet experts here.  I'd like to keep the finish as original as possible but don't know if that's achievable, as I like things finished really well.  So should I give Howard's RaF a try on the tops first, and if that doesn't work then sand.  Any thoughts here are appreciated.

The other exterior issue are the grills, obviously different color, but I assume this is just from one being in the sun, so I found some 20 ct. undyed Permin/Wichelt linen to replace.  I will also need to get some badges, as they are missing.

I will open them up later and get to the capacitors and resistors.  I still have some of RoyC's sealant left from my last project but might need some more.

Thanks in advance for the help.

Lorne

[RickB]

Hi Lorne, I always try the Howards on the bottom first. As for the grilles bleach/wash or new ones-good luck.

Rick

[JKent]

Weather permitting I would try a chemical stripper like Citra-Safe or a soy-based. Assess when clean and dry then hand sand carefully. Those 3 dark spots look like the only possible challenge. You may have to use a wood bleach on those. 
Glen is the expert on patching veneer. I’d use brown epoxy such as Mohawk or JB Woodweld (+ Mixol 22). The big chunks are in inconspicuous spots. After all that assess and decide whether to stain. 
The new linen should be nice for the grilles. I no longer sell reproduction badges but eBay seller “audiotagsiowa” has what look to be nice ones for $10/pair. I don’t know if the Sixes originally had the flat aluminum or the cast badges with screw backs. I may have the cast ones. 

[RTally]

Those tops are not too bad. You have some stains, but they should come out.

The cabinet finish is oil.

I suggest first wiping the cabinets with mineral spirits to get the surface dirt off. Then you can apply some BarKeepers Friend (oxalic acid) to the dark water spots to remove them. Some suggest mixing the powder with denatured alcohol. Apply the wet mixture to the dark spots, let sit for a minute, and wipe off. If that does not do it, reapply and wait longer.

If the color of the top no longer matches the sides, I suggest another application of mineral spirits to remove more of the old oil and dirt. If there are surface imperfections, you could use sandpaper, lightly. I would use 120 to 180 grit. Be careful not to sand heavily near the edges.

I like to use Danish Oil, non-tinted to refinish my cabinets. Some like to use tinted Danish Oil, such as walnut. I prefer a lighter finish, but use the tinted if you want a darker finish. I like to apply the Danish oil, wait about 5 to 10 minutes, and then wipe off the excess oil with a paper towel, rubbing the wood so that there is no oil on the surface. I then let it dry for an hour or two. I do this 4 or 5 five times, stopping when the oil no longer soaks into the wood.

[JKent]

Good advice from RTally. I have a bag of oxalic acid here and that's what I meant by "wood bleach" (the chemical name had escaped me) but I did not know Bartender's Friend was the same thing. Will have to get some!

I had forgotten the Sixes were oiled walnut. The Fives and some others have an impenetrable hard finish of some kind. Probably varnish. 

Here are some I did about 4 years ago. Pretty sure I used at least one coat of Mahogany Watco to get that warm tone. Grilles were re-covered in linen as you plan to do.

[LorneG]

I was able to get quite of bit of work done on these since the last post.

 

I removed the 12” woofers, that aren’t even close to that size, and fiberglass dampening.  Everything is as expected, except the woofers have some corrosion.  I’m not sure how that happened as no signs of water damage, but I think I can just use a brass wire brush to remove the corrosion?

 

I next removed the terminals, switch (mark the top), caps, resistors and marked all of the connections with tape. This will make it much easier to solder the new caps and resistors in place, which were ordered and received from Meniscus Audio, a local business to me, and they threw in some candy!

 

Thanks @RTally @GD70and @JKent for the refinishing advice.  After I cleaned the cabinet with mineral spirts, I decided to sand and use oxalic acid on the top water stains.  I started with 220 with an orbital, then did 320 and 400 by hand.  I'm really happy with the results.  The water stains are no longer visible.  There are a few nicks on the edges, but I decided not to try and fill them but to leave for vintage character.

 

Again good advice from @RTally, as I chose to simply finish the cabinets with Tried & True Danish Oil, with no pigment.  I’ve done one coat, and will do at least two more with a 0000 steel wool dry burnish before each.

 

New 20ct. 100% linen cloth and used badges have been ordered.

 

I do one at a time, so I hope to have the first one running this weekend.

[JKent]

GREAT progress! Wood looks beautiful. Just remember to put the rubber washers and shoulder washers back in place. I hate those aluminum plates 

[LorneG]

Good reminder.  I was actually surprised at how the rubber  had deteriorated, so I think I will look in the Ace Hardware bins for some thicker replacements.

[dxho]

Steel wool can leave fragments that get pulled into driver magnets and
sometimes stain the wood if (when) they rust.

[JKent]

Try white Scotch Brite

 

[GD70]

Very nice! You’ve done them justice! Once you’re done, you will be amazed at how smooth these sound, that deep buttery bass is so satisfying. 
I was recently gifted a set, circa 1968, that are in overall nice shape. The gifted also included the caps. These have the crossovers in the epoxy tub, and he wasn’t confident he could do the job, and he’s selling his house. Anyway, I always love seeing these old girls being brought back to the stage to sing!

Cheers, Glenn

[RTally]

The corrosion on the woofers likely contains cadmium, which is very toxic. Please take precautions to avoid inhaling any dust or particles.

Some advocate wiping loose corrosion with damp cloths and then disposing the cloth as hazardous waste.

If it was my woofers, I would consider painting over the corrosion to fix it in place. Then return them to service.

[LorneG]

@RTallyagreed, I don't think brushing it off will do much good.  I think it might be from flux that dripped down when these were originally soldered, as both speaker have the corrosion by the terminals?  Do any of you rotate the woofer 180* when re-installing?  I read a few people that do that, but with these woofers it doesn't seem necessary?

[GD70]

I usually rotate woofers that haven’t been removed since they were assembled. Never had any I’ll effects doing this. 

[LorneG]

I got all old capacitors and resistors de-soldered and removed and put in new, longer wires in for the two new 2.2uf caps.  New caps and resistors were soldered in and all the wiring was soldered or connected.  I put the  terminals back, with new rubber washers and reinstalled the switch with some Mortite caulk to make it air-tight.  First test of the new electronics, and it sounded great, with limited bass as expected.  I now just need to refill the cabinet and caulk the woofer, then push test to see if the first RoyC sealant application is sufficient.

I'm sure they sound the same as Daytons, but the ClarityCaps are sexy!  Also, here my wiring diagram that helps me in the installation of the electronics.

KLH Model Six (late) Wiring Drawing.pdf

[JKent]

Nice neat job. Are the new washers shoulder washers? Those screws have to be entirely insulated from the metal plate. 

[LorneG]

@JKent good catch.  I ended up using the original nylon washers, as one of the two has a small shoulder and then putting rubber washers over both to get a bit more height.  The new rubber washers have a same hole size but are just a bit wider.  The original washer are very thin.  I thought about using a nylon bushing to completely insulate the terminal hole, but I couldn't find one the right size (too tall).  There has to be a better way of engineering these, as I agree, even with the original washer w/ shoulder it seems that the terminal bolt is susceptible to touching the inside of the terminal hole?  The same with the switch in terms of being air-tight - I used some Mortite on the inside but it makes a bit of a mess, and the screw-on locking ring on the outside is hard to get tight.  Lots of bad engineering on this plate.

Also, de-soldering the switch is a lot of work, as the original has plenty of solder and the wires are wrapped tight.  I was afraid I might harm the switch with all of the heat going into the switch terminals for a prolonged period of time in order to get the original wires off, but the switch seems to be working fine. 

[LorneG]

I completed surgery on the second speaker.  I should back up and say that the second cabinet came out really well with just some cleaning and sanding.  This one had worse water stains than the first, but they came out on the first sand without having to use oxalic acid like I did on the first.  Again I used mineral spirits, 220, 320, 440 mostly by hand except for the first 220 pass, and then three coats of Tried & True Danish Oil with 0000 steel wool burnish between coats.  I really like the Tried & True oil vs. Watco.

I remove the switch and terminals to make de-soldering, deoxit and re-soldering new parts/wires in easier.  I replaced the caps, resistors and added some new wires.  Soldering is fun and I still enjoy the looks of the ClarityCap CSAs made by good folks in Wales.  I know Daytons probably sound the same, but I'm a sucker for aesthetics.  A couple things I have discovered:

• The switch has a channel on the top of the treading to attach to the speaker.  This certainly seems to be an air leak, so I put a circle of Mortite rope caulk on the inside, between the nut and the back of the plate.  This should seal it.
• The existing shoulder washer doesn't seem long enough to completely shield the terminal screw from the plate, so I found new ones in the bulk bins at Ace Hardware.  I put the new washer on the inside, and the old shoulder washer on the outside and got complete isolation from the plate.  I also put a very tight-on-the-terminal-screw rubber washer on the inside to give it a better air seal and give it some height above the terminal plate.
• The existing wires that connected with wire caps had some oxidation on the ends, so clipped and re-stripped to get to nice shiny silver wire.

Everything installed well and the first sound check was good.  I had re-sealed the woofer surround and dust cap about a week ago (via RoyC's sealant), so back in went the original fiberglass insulation, woofer was spun 180* degrees and resealed with caulk rope.  The push test on the woofer was not good enough, so on when another coat of sealant. 

I'm still waiting on the grill fabric, which was ordered three weeks ago!  It's 100% 20ct. linen.  I will try to put some pictures up tonight after sealant is dried and I get them hooked up.

[DavidR]

Nice work and good choice on caps.

[LorneG]

I finally finished these up.  It took three weeks for the fabric to arrive, so I got to work getting the grills recovered.  I used 100% linen, 20 count.  After ironing, stretching and stapling, I wasn't really happy with the look, so I sprayed the wrapped grills with quite a bit of water and used a hair dryer on high to tighten them up.  It worked great and the grills look awesome.  I think the cabinets look amazing, and I'm glad I decided to sand them.

I didn't like the look or sound of these floor-standing speakers on the floor, so I also decided to build some AR-style speaker stands.  Experimenting with height, I found 8" sounded better than 12" or 18", but settled on 6" to match the console.  The stands were a bit harder/more complicated than I thought to build, especially the doweling, but they came out fine.  I made them a little smaller than the speaker footprint, and used Herbie's Fat Dots (small) for isolation under the speaker and felt pads on the floor legs.

Here is everything completed and hooked up.  The Sixes sound amazing, especially the mid-range but the bass is pretty strong too.  Due to their efficiency, the Sixes are a great match with my 1961 HH Scott 299B tube amp and 1963 AR XA turntable - true New England sound and similar vintage.

The next project looks like refurbishing a Thorens TD-150 with a SME 3009 II Improved tonearm and a Sure V15 III cartridge.

[GD70]

Excellent! Enjoy the tunes!

[LorneG]

Glenn - thank you so much.  This was my favorite restore so far.  I was just listening to Stan Getz + Charlie Byrd this morning - sounds so magical on this system.

I haven't had good luck finding my next speaker restoration project.  The vintage ARs, KLHs, or Original Advents I've been finding locally are either in horrible shape, have been disastrously repaired, or are really expensive; often all of the above.   I reluctantly passed on two different but local pairs of KLH 23s, as both had so much water damage to the cabinets.

I have been up to my eyeballs restoring turntables (1965 TD-150, 1978 Micro Sekei DD-40, and now working on a 1971 TD-125) and I also picked up a Fisher 500C that needs the insides worked - something new for me to learn.

I have been considering pulling the trigger on a pair of Tannoy 15" Gold monitor LSU/HF/8 Dual concentric with crossovers (no cabinets) that are local, in great shape, but pricey.  I also have a line on a pair of Altec 604-C Duplex drivers, with no cabinets or crossovers.  The cabinet building + tuning, and crossover (re)building aren't a problem for me, it's the size of the boxes that these take just isn't practical, and I don't see a good local resale market.