Introduction and question on KLH model 6

[Guest rczetli]

First an introduction: My name is Rob Czetli and while I have a degree in Electrical Engineering I have worked in I.T. my entire career. I have been designing, building and restoring audio equipment for about 25 years now and as I approach my 40th Birthday this November (where did the time go?) I decided to put together a vintage system of about the same age.

I just purchased a pair of KLH 6s for $25.00 and while they need some work cosmetically, one of them plays beautifully and the other has a frozen woofer. Can the woofer be repaired or would it even be worth the cost of repairing the woofer or should I just look for another Model 6 woofer to replace it? That being said, anyone have a model 6 woofer they would like to sell? ;-)

Thanks for all of the good information!

Rob

[Guest matty g]

Hey Rob -

First of all welcome to the CSP - There is much information to be had here and some very decent people associated with this site.

To answer your question, no it's not worth having the woofer fixed (assuming it's the screwed in type) but yes it is worth picking up a good used one - they show up on e-bay all the time. I think I might even have one in one of my many "junk" boxes in the attic if e-bay doesn't work out for you. Matter of fact, I have a nice pair of Model Sixes just sitting around that I'm willing to part with if you want to go mongo quad! I'm in Central NJ if you care.

Just curious - what kind of vintage stuff are you driving the Model Sixes with...also what era Sixes are they. I'm assuming they aren't the older model with the epoxied in woofers. Also wondering if the tweeters work!

Matt

[Guest rczetli]

Thanks for the welcome Matt.

I have been looking for the driver on ebay but I have only seen a lone Model 17 woofer. I get too impatient with ebay. When I'm ready to get to work in my shop, I just want the parts!

How much do you want for the pair of Model 6s? I might be interested and I definitely would be interested in the driver if you have one. I live in Lancaster, PA so a roadtrip is definitely not out of the question.

As for equipment, for this system right now I have a Mcintosh MC-2100 that I got a really good deal on and I have a Dynaco PAT 4 that has been upgraded with new power supply and capacitors but I can also run the 2100 directly. I also have a Voice of Music stereo tuner that was given to me by a friend. I want to finalize the speakers and I am still looking for an AR XA turntable.

This stuff is just too much fun!

Thanks again.

Rob

[JKent]

Hi Rob and welcome

You don't have to look for just a Model Six woofer--the classic KLH speakers had some interchangeable drivers. According the the KLH Six and Seven brochure in the Library, both used a 12" woofer (that means there is an error on the Excel spreadsheet btw--that says 10" for the 6). Anyway, I think you should be able to use any 12" KLH woofer from an early, clasic KLH. I'll leave it to those members who know more about these, but I'd broaden the search. Good luck!

Kent

[Guest matty g]

Hi Rob -

Rather than clutter up the page, I'll e-mail you through the forum with the specifics. Give me a day or so to pull the parts boxes out and check everything electrically. Don't worry - I'm not out to get rich, just wanna help. I know that cooked speaker feeling!

Talk to you soon

Matt

[Andy]

^You have to be careful mixing annd matching woofers, some have the same frame diameter but are not the same....example, the Model seventeen has a smaller magnet & voice coil than the Model six. Also, the Seventeen and Twenty look the same, but the Twenty is 4 ohm. And of course the models Five and Twenty Three woofers are bigger then all the above. Finally, the later woofers from 1970-75 seen in models 30,31,32,33,56, etc. are the same speakers (both 8" and 10") seen in earlier models 6,17,24,26 and can be used, but take a close look before buying....look up specs if you can.

As mentioned before, if you have a model Six with a epoxied in woofer (serial number 93,000 or lower..,I think) you'll have a whole different can of worms on your hands.

Andy

[Guest rczetli]

They are later model speakers and the drivers are not epoxied in place so that makes things easier. I plan on upgrading the caps with Solen and giving everything a good cleaning. These have the vinyl veneer which is a little ratty too. I have several rolls of veneer from Parts Express that I used on other projects. Have any of you ever re-veneered your cabinets?

Thanks to everyone for the good information. I’m sure I will have more questions as the restoration begins this weekend.

Matt, I will look for your email.

Thanks,

Rob

[JKent]

> Have any of you ever re-veneered your

>cabinets?

check this thread for starters

http://www.classicspeakerpages.net/dc/dcbo...ing_type=search

[boreas]

JKent wrote:

>According the the KLH Six and Seven brochure in the Library,

>both used a 12" woofer (that means there is an error on

>the Excel spreadsheet btw--that says 10" for the 6).

I don't know but it could be an error in the Brochure. The same brochure also states that the width of the speaker cabinet is 12 5/8". That would be too small to house a 12" woofer. Since the sides of the cabinet are around 3/4" thick that would leave only about 11 1/8" for the woofer.

My Model Thirties are 12 3/4" wide and have 10" woofers. There is no room for anything bigger. So the long and the short of it is the brochure *has* to be wrong, either in the size of the woofer or in the width of the cabinet.

I've always been under the impression that the Model Six and Model Thirty used the exact same speakers. If that's the case the Model Six has a 10" woofer and 4" tweeter because that's what's in the Thirties.

jb

[Guest matty g]

Hi -

The Model Six cabinet is actually 12 11/16" wide and houses a woofer with a 10 3/4" frame and a 9 3/16" cone including the surround. The consumers report book from 1968 lists it as being 12 3/4" x 23 1/4" x 11 3/4" and tipping the scales at 27 lbs.

The Model Twenty and Seventeen woofers are 10 1/8" diameter frames with 8 3/4 inch cones including surrounds. The cabinets are listed as being 12" x 23 1/4" x 9" and weighing 24 lbs. I no longer have any of those to compare the cabinet dimensions to , but they're probably close as C.U. is pretty anal about that kind of thing.

Matt

[boreas]

matty g wrote:

> The Model Six... houses a woofer with a 10 3/4"

> frame and a 9 3/16" cone including the surround.

>

> The Model Twenty and Seventeen woofers are 10 1/8"

> diameter frames with 8 3/4 inch cones including

> surrounds

Thanks, Matt. I think that clears some things up. The Model Six apparently has neither 10" woofers, as stated in the library spread sheet, nor 12", as the KLH brochure reads, but 11" (more or less) woofers. Go figure!

Also, the Model Thirty would appear to have the same speakers as the Seventeen and Twenty, not the Six (again as listed in the spread sheet). I just measured my Thirties and, at least in terms of frame and cone dimensions, they're the same as what you've listed for the Seventeen and Twenty.

jb

[tysontom]

>JKent wrote:

>>According the the KLH Six and Seven brochure in the

>Library,

>>both used a 12" woofer (that means there is an error

>on

>>the Excel spreadsheet btw--that says 10" for the 6).

>

>I don't know but it could be an error in the Brochure. The

>same brochure also states that the width of the speaker

>cabinet is 12 5/8". That would be too small to house a

>12" woofer. Since the sides of the cabinet are around

>3/4" thick that would leave only about 11 1/8" for

>the woofer.

>

>My Model Thirties are 12 3/4" wide and have 10"

>woofers. There is no room for anything bigger. So the long

>and the short of it is the brochure *has* to be wrong, either

>in the size of the woofer or in the width of the cabinet.

>jb

JB,

It is true that the KLH Six cabinet is only 12 5/8-inches wide, but the original speaker did not have a speaker frame in the traditional sense; it was epoxied in place. If you drew an imaginary circle around the outside dimensions of the pipe frames and epoxy filling used to support the magnet assembly, it would be at least 12-inches in diameter. In the loudspeaker industry, the woofer's dimensions are based on the frame diameter, so the imaginary diameter of the early KLH Six is at least twelve inches. The cone's surround, too, is nearly up against the sides of the front baffle.

http://www.classicspeakerpages.net/dc/user_files/2674.jpg

KLH Model Six Epoxied Woofer

I have also seen this description in several pieces of literature over the years, so KLH apparently stuck by the "12-inch" description.

--Tom Tyson

[boreas]

>It is true that the KLH Six cabinet is only 12 5/8-inches

>wide, but the original speaker did not have a speaker frame in

>the traditional sense; it was epoxied in place. If you drew

>an imaginary circle around the outside dimensions of the pipe

>frames and epoxy filling used to support the magnet assembly,

>it would be at least 12-inches in diameter. In the

>loudspeaker industry, the woofer's dimensions are based on the

>frame diameter, so the imaginary diameter of the early KLH Six

>is at least twelve inches.

>--Tom Tyson

Ah, I think I get it!

So, the speaker surround - the actual cloth - was epoxied directly to the front surface of the baffle, making the baffle in essence a part of the frame? Then there was a sub-frame epoxied to the back side of the front baffle which carried the magnet?

Interesting. Must have made them time consuming/expensive to build. I guess the switch to the screw-in woofer necessitated the reduction in its size.

Thanks.

jb

[tysontom]

jb,

Yes, the surround, as well as the magnet assembly and steel-tube frames, were epoxied in place. Henry Kloss even took out a patent on the alignment jigs themselves. I am convinced that Kloss' primary intent was to develop a process that would make production assembly very consistent from speaker-to-speaker as they went down the line, and the results were that each of these epoxied-in woofers was very close in tolerance and specification -- as good as anything in the industry. The speaker assembly also stayed in alignment once in use, but I think that the downfall was the cost of repair. Their thinking was that the only way to repair these speakers was to return them to the factory. Yes, the front-mounted frame woofer that replaced the earlier design was made smaller, but KLH continued to call it a “12-inch woofer.” I haven’t measured the difference, but I think the cone size basically stayed constant with the changeover.

The early KLH factory speaker warranty, which was a "Limited" and not a "Full" warranty, included parts and labor for two years, did *not* include freight to the factory (this hurt KLH somewhat initially in that arch-rival AR had a "Full" five-year unconditional warranty on speakers that included everything including freight to and from the factory). Thus, during the warranty period, KLH bore the brunt of the cost of maintaining the speaker in good working order. Once past the two-year period, with cost pressures reduced, the company still required an owner to return defective speaker to the Cambridge factory for repair -- but at owner's complete expense, which could be costly for the owner. When a speaker was returned to the factory, KLH repair personnel had to cut out and discard the grill cloth, remove the cone and voice-coil assembly, make the necessary repair inside the cabinet, and then reinstall all-new components from cones to grill cloths. By the time KLH migrated to removable drivers and Velcro-attached grills, the warranty went up to five year (but still no transportation). Henry Kloss had by now moved on to newer ventures, such as the Advent Corporation. Later on, however, as KLH was beginning to wane as a viable company, problems began to develop with post-oil-filled capacitor Model Four, Six and Sevens with epoxied-in woofers and tweeters; there was no good way to repair these speakers out in the field without cutting holes in the speaker cabinets.

--Tom Tyson

[boreas]

> jb,

> Later on, however, as KLH was beginning to wane as a

> viable company, problems began to develop with

> post-oil-filled capacitor Model Four, Six and Sevens

> with epoxied-in woofers and tweeters;

>

> --Tom Tyson

Thank you, Tom. Great information!

I'm in the less-than-enviable position of having both Kloss era and Singer era versions of the same model speakers here: a pair of Model Thirties from each period and a mixed pair of Model Twenty-twos. The difference is noticeable.

jb

[Guest nolanpk]

> jb,

> Later on, however, as KLH was beginning to wane as a

> viable company, problems began to develop with

> post-oil-filled capacitor Model Four, Six and Sevens

> with epoxied-in woofers and tweeters;

>

> --Tom Tyson

Thank you, Tom. Great information!

I'm in the less-than-enviable position of having both Kloss era and Singer era versions of the same model speakers here: a pair of Model Thirties from each period and a mixed pair of Model Twenty-twos. The difference is noticeable.

jb

Rob,

Congratulations on your project! I am pleased at your choice of components. I have two pair of 6's powered by a MC 2100 and Marantz 33 preamp, with AR XA turntable and Marantz 23 tuner. They sound wonderful. The amp complements the speakers very well. I experimented with the speaker positioning, and settled with the speakers stacked vertically, with the top cabinet inverted so that the tweeters are coupled. I have two other pair of 6's that need tweeter repair, but the grilles are glued on. I have been trying to imagineer a way to remove the grilles without destroying them. Good luck with your system!

Pat