nickdinatale
Active Member
Close to a year and a half ago I purchased my first pair of KLH Model Fours. They were in working order, but not perfect cosmetically. I had read all I could find on AK, as well as the rest of the internet, so I already knew that they were pretty well-regarded, and semi-rare. I was in the midst of collecting pretty much every 60s to early 70s KLH that I could scoop up for a reasonable price. Needless to say, I was pretty excited to finally get my hands on a pair of Fours.
Originally a direct competitor to the AR-3, the KLH Four definitely lost the competition as far as popularity. The highest Model Four serial that I have come across is number 7434 (which I believe was on the auction site), while the AR-3 and 3a made it into the 90k range, and were produced into 1976. Price points for each were about the same - the KLH Four retailed from $209 (utility cabinets) to $231 (walnut) in 1960. The Model Four was also eclipsed by the massive popularity of the KLH Model Six, which debuted the same year, but was nearly half the price. Nevertheless, the KLH Model Four found an audience at CBS Records, serving as their monitor speakers, according to Henry Kloss in a 1996 interview.
Note that the forum I found this in references these as “upside down Model Sixes,” but the Model Four had the badges located in the upper right, so I’m guessing that these are in fact Model Fours being used.
Upon listening to the Model Fours for the first time, I was pretty happy with them. They were pretty laid back, but still very musical for having 50+ year old capacitors inside. I was very content and didn’t intend to recap them right away. Some time passed, and eventually I realized that they just weren’t pulling their weight, so I set them aside as a future project to undertake.
That time finally came last July, as my childhood dog, Kasey, became ill, and I spent a month living at my parents in order to spend time with her. I wanted my dad’s help with these anyway, and also wanted more room to work on them, as I already knew they would be a very involved restoration. The distraction was also a welcome bonus for both of us, I think.
Originally, I set out to restore the speakers via a recap, new surround sealer, and a cabinet refinish. As an added bonus, I wanted to do it without having to destroy the original grill cloth. I removed the rear plate that covers the hole where the crossovers are suspended and began lightly chiseling away at the epoxy. (Note: don’t lose the black rubber grommets that insulate the A,B, and C terminals!) The epoxy crumbles pretty easily, so it didn’t take all that much force to work through it. If you’re giving this a go yourself, the main key is to take your time and be careful to not damage the crossover, particularly the inductor, which has bare copper wire that is quite thin. Stay toward the edges if possible.
If a recap is all you’re trying to do, you can access the double 2uf capacitor (pictured) and replace it. The 3uf cap is mounted on the rear panel of the cabinet, just off to the side of the crossover. (See two photos ahead). You may be able to reach in and remove it, or at least clip the leads. Make note of which color wires are connected where so that you can reference the schematic (included later). It’s also a good idea to label each cabinet and crossover with the serial it belongs to in order to keep things separate. Taking a photo to note the orientation of your switches to the plate is also crucial for reinstallation.
Our next step was to open up the rear panels. We laid out even edges along the back of the cabinets and marked them with masking tape for cut lines. At the time we didn’t know how thick the cabinets were, so we made plunge cuts with a circular saw. (The answer is 3/4”). From there, we used a jigsaw to get the corners. Even having laid everything out, the cuts weren’t perfectly straight, so just take your time and do the best you can.
After removing the rear panel, the familiar sight of pink fiberglass insulation appears. Underneath the insulation lies the front driver board. Notice the thin black cloth covering the woofer - this is important. As the woofers aren’t built into basket frames, the black cloth is stapled down in a very taught manner in order to protect the woofer’s cone from encountering any interference from the insulation pressing against it. (More on this later). At this point in time, I was still hoping to save the grill cloth. (Notice it peeking around the corners of the front board).
Unfortunately, I soon realized that the grill cloth was doomed to be ripped off. We actually removed the entire front driver board from the cabinet completely, thinking it would allow for removal of the cloth. This wasn’t the case, as the cloth was both stapled down, and then the front panel was glued and seated, sandwiching it in between. As we removed the panel, the cloth was ruined. From there, I removed it from the front panel and then had to tediously chisel it away from the main cabinet, and from the edges of the driver board in order to allow for a clean seating of the panel back into the cabinet.
Inside of each cabinet there were even stamps from when they were built. Mine were in red and said “Denny May 1964 Roll” and “Denny June 1964 Roll” respectively.
(cont.)
Originally a direct competitor to the AR-3, the KLH Four definitely lost the competition as far as popularity. The highest Model Four serial that I have come across is number 7434 (which I believe was on the auction site), while the AR-3 and 3a made it into the 90k range, and were produced into 1976. Price points for each were about the same - the KLH Four retailed from $209 (utility cabinets) to $231 (walnut) in 1960. The Model Four was also eclipsed by the massive popularity of the KLH Model Six, which debuted the same year, but was nearly half the price. Nevertheless, the KLH Model Four found an audience at CBS Records, serving as their monitor speakers, according to Henry Kloss in a 1996 interview.
Note that the forum I found this in references these as “upside down Model Sixes,” but the Model Four had the badges located in the upper right, so I’m guessing that these are in fact Model Fours being used.
Upon listening to the Model Fours for the first time, I was pretty happy with them. They were pretty laid back, but still very musical for having 50+ year old capacitors inside. I was very content and didn’t intend to recap them right away. Some time passed, and eventually I realized that they just weren’t pulling their weight, so I set them aside as a future project to undertake.
That time finally came last July, as my childhood dog, Kasey, became ill, and I spent a month living at my parents in order to spend time with her. I wanted my dad’s help with these anyway, and also wanted more room to work on them, as I already knew they would be a very involved restoration. The distraction was also a welcome bonus for both of us, I think.
Originally, I set out to restore the speakers via a recap, new surround sealer, and a cabinet refinish. As an added bonus, I wanted to do it without having to destroy the original grill cloth. I removed the rear plate that covers the hole where the crossovers are suspended and began lightly chiseling away at the epoxy. (Note: don’t lose the black rubber grommets that insulate the A,B, and C terminals!) The epoxy crumbles pretty easily, so it didn’t take all that much force to work through it. If you’re giving this a go yourself, the main key is to take your time and be careful to not damage the crossover, particularly the inductor, which has bare copper wire that is quite thin. Stay toward the edges if possible.
If a recap is all you’re trying to do, you can access the double 2uf capacitor (pictured) and replace it. The 3uf cap is mounted on the rear panel of the cabinet, just off to the side of the crossover. (See two photos ahead). You may be able to reach in and remove it, or at least clip the leads. Make note of which color wires are connected where so that you can reference the schematic (included later). It’s also a good idea to label each cabinet and crossover with the serial it belongs to in order to keep things separate. Taking a photo to note the orientation of your switches to the plate is also crucial for reinstallation.
Our next step was to open up the rear panels. We laid out even edges along the back of the cabinets and marked them with masking tape for cut lines. At the time we didn’t know how thick the cabinets were, so we made plunge cuts with a circular saw. (The answer is 3/4”). From there, we used a jigsaw to get the corners. Even having laid everything out, the cuts weren’t perfectly straight, so just take your time and do the best you can.
After removing the rear panel, the familiar sight of pink fiberglass insulation appears. Underneath the insulation lies the front driver board. Notice the thin black cloth covering the woofer - this is important. As the woofers aren’t built into basket frames, the black cloth is stapled down in a very taught manner in order to protect the woofer’s cone from encountering any interference from the insulation pressing against it. (More on this later). At this point in time, I was still hoping to save the grill cloth. (Notice it peeking around the corners of the front board).
Unfortunately, I soon realized that the grill cloth was doomed to be ripped off. We actually removed the entire front driver board from the cabinet completely, thinking it would allow for removal of the cloth. This wasn’t the case, as the cloth was both stapled down, and then the front panel was glued and seated, sandwiching it in between. As we removed the panel, the cloth was ruined. From there, I removed it from the front panel and then had to tediously chisel it away from the main cabinet, and from the edges of the driver board in order to allow for a clean seating of the panel back into the cabinet.
Inside of each cabinet there were even stamps from when they were built. Mine were in red and said “Denny May 1964 Roll” and “Denny June 1964 Roll” respectively.
(cont.)