Early KLH Drivers

[Guest Droog]

Here's an example of some early KLH.....the seller is parting out a model four, ebay #5726165535 and #5726165925. As you can see, you need a saw to remove drivers & crossovers due to them being epoxied in (no mounting screws). Notice the unusual woofer, with a concave dust cap and a convex cone.....oposite of the later drivers. These date to 1958-60, and you would have to be pretty talented in cabinet construction to rebuild them into a usable speaker! The service people at KLH must have gone nuts when repairing these, requiring major surgery just to get into the cabinet.

[tysontom]

>Here's an example of some early KLH.....the seller is parting

>out a model four, ebay #5726165535 and #5726165925. As you

>can see, you need a saw to remove drivers & crossovers due to

>them being epoxied in (no mounting screws). Notice the

>unusual woofer, with a concave dust cap and a convex

>cone.....oposite of the later drivers. These date to 1958-60,

> and you would have to be pretty talented in cabinet

>construction to rebuild them into a usable speaker! The

>service people at KLH must have gone nuts when repairing

>these, requiring major surgery just to get into the cabinet.

The 16-ohm KLH Four was KLH's answer to the Acoustic Research AR-1, (and later the AR-3), and it was an excellent speaker. I believe the very first versions used a special GE tweeter (it used two of them with a sort of 3-way crossover whereby the two tweeters worked in the midrange but only one tweeter worked at the highest frequencies), but later Kloss made his own tweeter which appears to be shown in the eBay auction. The Four was relatively expensive at $231/each back in 1958. Appearance-wise it was a truly beautiful speaker, slightly larger and heavier than the KLH Six, and had a heavier woofer with about one-third octave deeper bass capability with its approximately 48 Hz resonance. It was almost -- but not quite -- the equal to the AR-1 and AR-3 in deep bass, probably closer to the AR-2 and AR-2a in distortion but with slightly lower reach. It was a deservedly top-rated speaker in Consumer Reports. The woofer did have the patented epoxied-in aluminum pipes for a speaker frame (like the early KLH Six, Seven), and you can see where the pipes are epoxied into the cabinet front in the picture. The cone was conventional, and the dust cap was convex in the usual fashion, incidentally, not concave. Many KLH Fours today suffer from chronic capacitor problems in the crossover, and there is really no fix unless the speaker is distroyed or cut open from the back.

KLH Fours did not sell in great numbers, principally because excellence and notoriety of the Acoustic Research AR-3. The AR-3 was definitely superior, but the KLH Four was still a superb loudspeaker and is now highly collectible, especially if a pair can be found that is in good physical and functional-operating condition. The 16-ohm impedance restricts output from solid-state amps, but otherwise the speaker does fine with conventional amplification.

--Tom Tyson

[tysontom]

>...The woofer did have the patented epoxied-in

>aluminum pipes for a speaker frame (like the early KLH Six,

>Seven), and you can see where the pipes are epoxied into the

>cabinet front in the picture. The cone was conventional, and

>the dust cap was convex in the usual fashion, incidentally,

>not concave. Many KLH Fours today suffer from chronic

>capacitor problems in the crossover, and there is really no

>fix unless the speaker is distroyed or cut open from the

>back.

>

One further comment: the surround, an impregnated-cloth material, was indeed inverted, or concave, as it was on the KLH Six and several other model KLHs. The dust cap was convex, I believe.

--Tom Tyson

[Guest Droog]

Tom, I'm sure you're right about the concave-convex structures of the surround, cone and dust cap of this early woofer......must be a photo illusion which makes all three components look oposite of the conventional set-up. I've not seen one in person, I'm leaving my 1958 model six's alone since they are working well. It is a shame such nice speakers can't be easily serviced and am surprised KLH didn't make the switch to the screw mounted drivers earlier then 1961 ?? Do the models one, two and three also have the epoxied drivers. The stress of servicing this set-up must have convinced KLH to make the change.

[soundminded]

I don't think it was the stress, it was the cost. If every time you have to replace a capacitor, you have to remove a woofer cone, work through the basket, and then recone it, the cost of repairs eats into the profits very quickly. It gets especially expensive when they keep failing under warrantee. And even if it isn't under warrantee, how can you charge as much to replace a capacitor as it costs to buy a whole new speaker system? You don't stay in business that way. Had the back been removable, at least they would have had a fighting chance. This could have been easily done with a neoprene gasket or a pair of gaskets and a small piece of molding around the inside to screw the back to. This is what I meant by bad enclosure design on another thread. On another message board, someone suggested removing part of the back. The bad news is that for a lot of them, the circuit boards for the crossover networks were epoxied in also. Didn't Mr. Kloss believe in screws and screwdrivers? Sheeeesh!

[tysontom]

>...This could have been easily done with a neoprene

>gasket or a pair of gaskets and a small piece of molding

>around the inside to screw the back to. This is what I meant

>by bad enclosure design on another thread. On another message

>board, someone suggested removing part of the back. The bad

>news is that for a lot of them, the circuit boards for the

>crossover networks were epoxied in also. Didn't Mr. Kloss

>believe in screws and screwdrivers? Sheeeesh!

Henry Kloss was an innovative man, but sometimes not terribly practical! The epoxied-in woofer demonstrates this innovation but it was terribly inpractical. Another good example was during the early days at AR while Kloss was the production engineer and plant manager. Ed Villchur had invented and patented the acoustic-suspension woofer, built a prototype, and left it up to Kloss to complete the first production AR-1 speaker. Kloss felt that the enclosure should be glued together without a removable back panel or front baffle board. This innovative cabinet construction went on to become the standard methodology in a/s speaker construction. Nevertheless, in 1954, Kloss struggled with a way to mount the AR 12-inch woofer into the new cabinet without getting into the back of the enclousure, the conventional way at the time. At first he came up a novel idea to cut the speaker hole, and then rout out an additional slot at the top and bottom of the woofer cut-out in order that the woofer might be "passed through" the woofer hole, be turned around inside the cabinet with a special jig, and then bolted from the back in the conventional manner. The holes would then be plugged and glued. This proved to be an insurmountable task, and Villchur suggested that he simply mount the speaker from the front; and while he was at it, he could rout out a slot for the speaker flange so the frame was even with the front surface of the baffle board, and that he should also use machine screws instead of wood screws to assist service efforts later on.

--Tom Tyson

[tysontom]

>Tom, I'm sure you're right about the concave-convex

>structures of the surround, cone and dust cap of this early

>woofer......must be a photo illusion which makes all three

>components look oposite of the conventional set-up. I've not

>seen one in person, I'm leaving my 1958 model six's alone

>since they are working well. It is a shame such nice speakers

>can't be easily serviced and am surprised KLH didn't make the

>switch to the screw mounted drivers earlier then 1961 ?? Do

>the models one, two and three also have the epoxied drivers.

>The stress of servicing this set-up must have convinced KLH to

>make the change.

The Models One, Two and Three were woofer-only speakers. Basically, the Model One system was a dual 11-inch (later referred to as a 12-inch) KLH Four woofer system with two 32-ohm woofers in parallel, and each in its own 1.5 cu. ft. a/s separate enclosure. These speaker "frames" were epoxied-in as well. The top compartment made room for the Janszen electrostatic tweeter. This speaker sold for $390 in Walnut or Birch. The Model Two was a single woofer (same woofer but in 16 ohms) with the compartment in the top for the Janzsen, and it sold for $206. The Model Three ($181 in walnut) was a KLH Four without the tweeters, much like an AR-1W. The models One, Two and Three apparently didn't sell much at all, because shortly thereafter they were discontinued and the Model Four and subsequently the Model Six were introduced with Kloss' own tweeters. Sales took off with the excellent Model Six, which actually kept KLH Research and Development afloat for many years. I am pretty confident that all of these speakers did have the concave surround, but convex dust cap.

--Tom Tyson

[Guest SPS 700]

I have three pairs of KLH model Six's. One pair that I just bought from the origional owner date from 1958(I was 7 when they were built). I even got the paperwork from KLH with them that explains the speaker. I cannot even get the grill covers off of these. Now I know why. The second pair I have looks like the 1958 ones but the grill covers come off and the drivers are held in by screws. The third pair much be much later because the cabinet constructin is different and the grill covers are brown. I also have three pairs of early Large Advents. After much experimentation I run 1 pair of KLH 6's and a pair of Advents stacked. This combination to me sounds great. Anyone else ever try this?