Another KLH 6 restoration: need help

[zonkerbd]

Thanks RTally for your words of encouragement, and thank you and RxDx for your suggestions. It didn’t occur to me to use a different method for each wire. So yes, I’ll attempt to solder an extension at the cap terminal for the red wire; and of course, I can just abandon the blue wire from the oil cap, and run a new one from the new cap to the 3-way switch.

Thanks.

 

[Dswankey]

As much as I would be exasperated by working on these epoxied speakers..... I desire a pair.

They are worth the effort!!

 

[loudnoises]

Here's a photo showing the backside of the plate and the gasket material.

Once the epoxy is gone, that plate needs reinforcement. It's not designed to seal anything, and not thick enough to not flex on the middle.


I used 1/4 oak ply. Mounted the switch and got some real posts. Highly recommend this.

As much as I would be exasperated by working on these epoxied speakers..... I desire a pair.

They're worth it. And I've still got the scars to remember the adventure. I could barley fit my left hand through the hole...

 

[loudnoises]

I have a pair of 1963 Model Sixes in my pile of speakers to work on. My tweeters have no sound, and I expect it is the caps. I plan on pushing out the baffle to access the internals. I want to save the cloth because it is in good shape.

I am in no hurry to work on this pair because I have a newer pair of Sixes that are connected in my office.

The epoxy woofers sound better IMHO. It's not huge, but I noticed it enough to sell the newer set...

 

[alteclipsch]

They're worth it. And I've still got the scars to remember the adventure. I could barley fit my left hand through the hole...

I suppose there are traces of skin and blood in lots of them after restoration.

Haven't some folks cut the backs out? Seems a thin kerf blade at 3/4" depth on a Fein saw, carefully applied, would be better. Pop in a new plywood back, good to go, no blood, no skin.

And dope the surrounds from the backside.

 

[Dswankey]

They're worth it. And I've still got the scars to remember the adventure. I could barley fit my left hand through the hole...

Yup, when I brought them to my tech, who is a big burly dude, he looked at me and said there is no way he could get his bear paws in there so I had to luckily I'm on the thinner side so with some effort and determination I was able to get in there. Pain in the ace but it was worth it.

 

[loudnoises]

I suppose there are traces of skin and blood in lots of them after restoration.

Haven't some folks cut the backs out? Seems a thin kerf blade at 3/4" depth on a Fein saw, carefully applied, would be better. Pop in a new plywood back, good to go, no blood, no skin.

And dope the surrounds from the backside.

I'm sure some do. I've also heard of knocking the baffles out from the back. To dope then you need to remove the linen coverings as well. It would be so destructive, and really not necessary? Even the thinnest kerf will leave you with a 1/16" gap in both dimensions. Huge really.

I do question how the doping would affect the sound I'm getting, but I'll go in from the front and just dope that side I think.

And yes, that stuff is like glass when it breaks. There's blood in mine...

 

[loudnoises]

Yup, when I brought them to my tech, who is big burly dude, he looked at me and said there is no way he could get his bear paws in there so I had to luckily I'm on the thinner side so with some effort and determination I was able to get in there. Pain in the ace but it was worth it.

I remember looking at the hole and just kinda accepting that it was going to suck. Luckily I'm good at working blind too, as ain't nobody getting to see inside and work inside at the same time.

 

[Dswankey]

Haven't some folks cut the backs out?

I remember seeing a thread were someone did just that however based on other threads and comments it could/would defeat the purpose of an ensealed enclosure and my guess is not everyone has access to or is sufficient in woodworking to the point of utilizing saws and then reinstalling

 

[alteclipsch]

To dope then you need to remove the linen coverings as well.

OK, I've got no skin in this game (or blood), but I think doping the woofer surrounds is essential, every KLH and AR I've had needed it, including my later Sixes. Unless there's a difference in the fabric there. Are you talking about the linen grill needing to be removed? I'd rather remove the back than destroy the grill. And I've seen AR speakers with a 1/16" gap around the plywood back, with a whitish caulking in there.

 

[loudnoises]

OK, I've got no skin in this game (or blood), but I think doping the woofer surrounds is essential, every KLH and AR I've had needed it, including my later Sixes. Unless there's a difference in the fabric there. Are you talking about the linen grill needing to be removed? I'd rather remove the back than destroy the grill. And I've seen AR speakers with a 1/16" gap around the plywood back, with a whitish caulking in there.

There's white linen on the backs of the drivers, and black on the front under the woven tan stuff. Unfortunately I already cut one a bit figuring out they were the epoxy driver era. Cutting the front fabric out, and replacing the grills is less aesthetically pleasing, but blowing the box apart seems worse on the sound side.

The only way I escape needing doping is if I'm somehow the exception to the rule. These haven't been more than 50 miles from where they were made, ever.

I'm also kinda waiting till I get some measurement tools too, so I can do one and compare etc.

It's kinda hard to imagine the low end improving. Mine don't really look like they ever had doping.

 

[zonkerbd]

UPDATE
My soldering iron died, so project was on hold for a bit. Thankfully it was still under warranty. I was eventually able to get a glop of solder onto an extension wire wrapped around the old cap terminal. Photo attached. It’s not the prettiest solder joint in the world, but it’s fairly solid and should hold. I had to Rube some tools to accomplish this, one stick to hold the solder and one to hold the soldering iron (photo attached), plus a small clip on light inside the cabinet. I first did a one handed wrap of the stripped extension wire, then performed the soldering surgery. Pfew, this was tricky, as the solder was small gauge and would bend easily so it was difficult to target. Anyway, glad this worked! I just left in place the other wire from the other terminal and capped off the end. This speaker now sounds really good, like the other speaker with much better high frequency coming from the tweeter! Thanks again for the ideas on wiring “around” the existing old cap.

INFO REQUEST
Before I put the insulation back, a question. The insulation for these speakers seems under-damped, at what I weighed to be only 8oz of fiberglass per box? This must be what was originally installed, but wondered if adding more would improve the sound at all? Is there some recommended quantity for the KLH 6? I assume they added an amount which maximized quality of sound and were not concerned about cost of fiberglass. I think I read on one of the forums that the AR 2ax’s were stuffed with 20oz of insulation(?!) Granted they are bigger boxes, but not by a huge amount. I thought I would ask this forum, as the process to add more and do an A/B compare between speakers would be kind of a pain.

Thanks!

Next I’ll have to decide on whether to cut out the front grille cloth in order to dope the surrounds, as discussed in the thread. Want to listen to them first for a bit before deciding.

 

[GD70]

The epoxy woofers sound better IMHO. It's not huge, but I noticed it enough to sell the newer set...

Agree. They go slightly deeper due to the longer excursion. Love the Six!

 

[loudnoises]

We're these always damped with the goo? Mine sure look really clean...

 

[GD70]

We're these always damped with the goo? Mine sure look really clean...

Yup! Part of the air suspension system. The surrounds must be sealed to really hear how great the bass is from these.

 

[zonkerbd]

An update and another request for advice.

UPDATE
Regarding my previous comment on the insulation seeming under-damped, I based that on the fact that there seemed to be a lot of open space in the cabinet. I decided to perform a simple test, I added an additional 4oz to the existing 8oz in one of the cabinets, leaving the other at 8oz and did a side by side compare (in mono mode). The 8oz cabinet sounds MUCH better, the speaker with the additional insulation sounding more muffled. So with this unscientific experiment, I’m concluding that the factory 8oz of insulation was tested to be optimal! I did fluff up the fiberglass before reinstalling the 8oz per cabinet, and sealing up the backplate. Photos attached of the crossover wiring (yeah, a lot of extra wire, I know. It made the soldering easier) and cabinets/grille cloths.

The speakers really sound great, with very full bass. I’m admittedly not a connoisseur of speaker evaluation. I liken this to a wine connoisseur, being able to pick out specific tastes and articulate them with a certain language. For me the low end of a speaker has 3 characteristics: a fullness of sound, a clarity (that can be picked up from a bass guitar), and a thumping that you can feel. The low end of these 6’s without sealing the surrounds sound very good to me, but I suspect could sound even better by sealing the surrounds. I also did a side by side compare between these 6’s and the KLH 17’s I restored awhile back, with sealed surrounds, and these 6’s sound significantly better, especially the low end.

So I’m undecided at this point on whether or not to rip out the grille cloths to get at the surrounds.

REQUEST FOR ADVICE
As you can see in the attached photo, the grille cloths have picked up what appears to be rust over the years. Does anyone have any advice on how to clean off the rust without removing the cloth. I think if I can clean the cloths to an acceptable level, I may leave these as is. As you can see, the cabinets are in pristine condition otherwise, and I kind of like the idea of not messing with them any further.

Thanks.

 

[Tim D]

The rust problem goes away if you cut them out to dope the surrounds. I'm just saying.

Nice looking cabinets btw.

 

[GD70]

There's white linen on the backs of the drivers, and black on the front under the woven tan stuff. Unfortunately I already cut one a bit figuring out they were the epoxy driver era. Cutting the front fabric out, and replacing the grills is less aesthetically pleasing, but blowing the box apart seems worse on the sound side.

The only way I escape needing doping is if I'm somehow the exception to the rule. These haven't been more than 50 miles from where they were made, ever.

I'm also kinda waiting till I get some measurement tools too, so I can do one and compare etc.

It's kinda hard to imagine the low end improving. Mine don't really look like they ever had doping.
View attachment 2155055

Oh it will, trust me, and every KLH of this era had doped surrounds and dust caps on the woofers. If you don’t see any, it’s because it’s completely dried out and gone.

 

[GD70]

An update and another request for advice.

UPDATE
Regarding my previous comment on the insulation seeming under-damped, I based that on the fact that there seemed to be a lot of open space in the cabinet. I decided to perform a simple test, I added an additional 4oz to the existing 8oz in one of the cabinets, leaving the other at 8oz and did a side by side compare (in mono mode). The 8oz cabinet sounds MUCH better, the speaker with the additional insulation sounding more muffled. So with this unscientific experiment, I’m concluding that the factory 8oz of insulation was tested to be optimal! I did fluff up the fiberglass before reinstalling the 8oz per cabinet, and sealing up the backplate. Photos attached of the crossover wiring (yeah, a lot of extra wire, I know. It made the soldering easier) and cabinets/grille cloths.

The speakers really sound great, with very full bass. I’m admittedly not a connoisseur of speaker evaluation. I liken this to a wine connoisseur, being able to pick out specific tastes and articulate them with a certain language. For me the low end of a speaker has 3 characteristics: a fullness of sound, a clarity (that can be picked up from a bass guitar), and a thumping that you can feel. The low end of these 6’s without sealing the surrounds sound very good to me, but I suspect could sound even better by sealing the surrounds. I also did a side by side compare between these 6’s and the KLH 17’s I restored awhile back, with sealed surrounds, and these 6’s sound significantly better, especially the low end.

So I’m undecided at this point on whether or not to rip out the grille cloths to get at the surrounds.

REQUEST FOR ADVICE
As you can see in the attached photo, the grille cloths have picked up what appears to be rust over the years. Does anyone have any advice on how to clean off the rust without removing the cloth. I think if I can clean the cloths to an acceptable level, I may leave these as is. As you can see, the cabinets are in pristine condition otherwise, and I kind of like the idea of not messing with them any further.

Thanks.

As hard as the decision is to cut out the original cloth, you can then reseal the surrounds, and watch fleabay for removable grills. I found a set with the exact same fabric in near perfect condition. You have options here.

 

[Tim D]

As hard as the decision is to cut out the original cloth, you can then reseal the surrounds, and watch fleabay for removable grills. I found a set with the exact same fabric in near perfect condition. You have options here.

Or you can make your own grills. If you are just a little handy it's not that difficult.