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Well I’ve spent my listening time today split between the Model Five, Model Twelve, and AR-3a. It’s not necessarily an even playing field; the -3a’s mids and tweeters have not been rebuilt, while I don’t believe the KLH drivers need any more restoration. But a couple of observations: In terms of pure, low frequency response, I think the -3a has the edge. A/B’ing between the -3a and Twelve using modern electronic music and some organ music, the -3a handles very low tones better. But it’s close. Between the Five and the Twelve (all tone controls flat), the Five sounds more forward on the mids and highs. I like both the KLH models over the -3a for rock music. Another fun experience was playing the Fives and Twelves together. That’s an impressive rock setup. Here’s a pic of the stack at the moment. All three of these projects wouldn’t have been possible without this forum, so thanks as always for that. George

Thanks @DavidR. It’s nice to have external crossover boxes (or easily-removable crossover boards like the Model Five). Much easier to make work look neat when you’re not working inside a cabinet. I thought the Five and Twelve crossovers were both fun projects.

Thanks, Roy. I’m adding opening up the Fives to redo that glue to my project list.

I finished replacing all the caps and resistors. I’m going to go back and hide solder connections with electrical tape, but they’re finished enough that I’m able to test them. I haven’t done work this extensive on many crossovers; feedback appreciated. Lovely sound, as expected. Tomorrow I’ll a/b them against the Fives.

Adding: for an extra $100, these can be delivered to the Boston area

Hi @RoyC He’s talking about the glue bead and plate loading at 9:20: And it’s both cabinets, although one seems to vibrate at a lower volume and than the other. There was no foam gasket for the backplate on mine; only the remnants of glue. George edit to clarify: one backplate vibrates when the program material is softer (but still loud), but I have to push the volume up a bit to get both backplates to vibrate.

I’m not sure I’ll garner a ton of sympathy with this post, but here goes… I have a vibration problem with my Fives. It’s coming from the back of the speaker and I can only figure it must be the backplate. I’ve thoroughly tightened down everything on that plate, so I believe it’s the plate itself. I glued the backplate in using wood glue as in the Novalux video series on YouTube. This happens on very low, loud passages. Specifically the track 1st 44 by Aphex Twin. Within the first three seconds, the backplate will rattle on those sustained notes. I’ve mentioned this track before on this board and it’s one of my favorite bass testing tracks. I know that modern electronic music uses bass far outside what was contemplated by the designers in the 60’s, but it’s what I’m into and I like the nice, tight bass that these old acoustic suspension speakers put out. The music has to be on the louder side for this problem to appear, but I’m driving them well within the rated power handling limits, of course. Is there anything I can do to cease the vibration? If I pull the crossover and backplate out again, is there something—some material—I can add to the seal there that would make a difference?

I had to replace one of the crossover boxes with one from eBay. When I opened the original up, there was a healthy mold specimen in the wood. I received the replacement crossover in the mail and it looks closer the original one that Kent posted. Thought it would be interesting to show them side by side, bearing in mind that the 50mfd caps in the crossover on the right were already replaced as mentioned above.

Thanks @RoyC. I had read previously that less sealant was needed on the mid surrounds. Those received a very light application. I also tried to be judicious with my use on the woofer surrounds, some areas still were not tacky or shiny after the second coat (primarily edges where the surround meets the cone and basket). I replaced the white foam gasket material with a ring of duct seal. I figured it may be better being able to press it into those screw channels. The above photos were before I installed the rest of the duct seal and screwed things down. I do think the seal is better now than with the old compressed white gasket. Thanks for your help George

Selling my spare set of AR-9s. Asking $800. Bought these intending to fix them and give them to family, but honestly, I don’t have a way to transfer them to the Southern US. Space is at a premium in my workshop so I’ve decided to part with them. All original drivers I believe, but I haven’t pulled drivers to confirm part numbers. One LMR woofer dust cap is pushed in. Probably needs to be recapped but I only removed one woofer to peek inside. All surrounds were replaced before me, although the subwoofers were a larger foam that someone cut down to fit. As such, there’s a radial splice in the foam. Also, someone drilled a small hole (maybe 1:4” in each backplate, I assume in order to modify the crossovers, but it appears they stopped. I was going to patch with some wood filler. Pickup in Midcoast Maine.

You and Roy are a wealth of knowledge on these. Thanks. I originally started this thread for questions about the crossovers, but I guess I’ll add some questions and observations about the cabinets. While I wait for caps and resistors, I’ve been working on resealing the cloth surrounds and sealing the drivers into the cabinets. Currently I have OK seals on the woofers. That’s after one layer of Roy’s sealant on the woofer dust cap and 2.5 layers on the surrounds (2 full coats and a touch up of spots that looked thin). When pushing in and releasing the woofer, I get a second or so before the woofer is back in its original position. Judging it against the seal on my Fives, it’s not quite as good…the woofer maybe returns in half the time as on the Fives. Is there anything about the large volume cabinet on the Twelves that complicates this process or should I be getting a similar seal here? It’s possible I still have some leaks I haven’t found. As for the midrange drivers, what’s the best way to tell they are sealed? On the Fives I just push one cone in and see if the other pushes out since they share the same enclosure. But since these have separate enclosures on the Twelve, is there a way to tell how sealed these are? I resealed each surround and plugged up the drilled wire holes inside each cabinet. A push-and-return test is pretty inconclusive to me on the midranges. Maybe they’re fine as is and I’m overthinking it. Speaking of the midrange enclosures, those are held on with four screws on the front of the baffle, unfortunately right where each midrange needs to seal. So more than not, each of those screw holes ended up with a small channel into the enclosure. I used duct sealer to plug those holes and to reseal the drivers. It’s unsightly but at least the grills and original grill cloth are intact so no one will have to see it. George

Thanks Kent. I already have replacement resistors coming in with the caps. I followed that same advice on my Fives as well. I ordered 15w resistors just because it was convenient for values from the supplier I used.

@JKent Thanks for your help! Those diagrams are terrific. And yes, that is the only double cap on mine. Speaking of, here’s a couple photos. Oddly enough, mine had two 47mfd caps instead of the two 50mfd. Pic of those too. They didn’t strike me as original but they were fastened down with the original cable tie. Maybe someone replaced the 50s and shoved the 47s under the same tie. I ordered 50mfd as replacements based off your previous work on the Twelve. Hopefully when I’m done my crossovers will look half as clean as yours.

I bought a pair of Model Twelves that need a restoration. I’ve ordered replacement caps and resistors but I have a question about the double 4mfd since there’s no available schematic. If I twist a pair of new 4mfd caps together so that they share a common lead, would that be the black wire in this photo of the crossover? That would leave the far ends of the double cap to take the place of the red wires. Thanks in advance

Thanks. I had no idea. I guess between the silver cap and redoing the seal in gasket tape, I’ll be opening these up again soon.

So I've now spent a couple of hours critical listening at moderately loud volumes, as well as a couple hours playing music in the background while I play with the kid. I can't hear any clear deficiency. I don't hear any unwanted distortion at all between the -10pi's and the -9's. . I'm going to take your advice and leave the Spragues in place. It's a treat to hear the original caps. Thanks for the heads-up @DavidR. I may open these up again in the next few weeks. I'll take that cap out of circuit and test it if I do.

Would you replace Sprague capacitors in the AR-10 Pi? I recently did some horsetrading with another hi-fi enthusiast and acquired a pair of -10 Pi's. Overall in good shape. No grills. Tonegen woofers from AR in the late-80's. A dimple on each tweeter but everything functioning. I went into it thinking I'd need to replace the caps. On my first test, there was distortion in the very low end during loud passages. Not much of an acoustic seal so I wasn't surprised. Today I opened them up and this is the first pair of AR's that I've come across that have Sprague caps (for all but the 100mf cap which is silver and in a different typeface). I heard that Sprague caps are often still in spec, so I closed them back up, sealing the woofer using duct putty (anachronistic, but I get a good seal and they carry it at Lowe's). The woofer distortion is gone now after playing back the same material. The midrange and tweeter sound okay to me on initial retesting. I'm sure the caps have drifted somewhat, but if everything is functioning and the drivers "sound" enough alike, would you still replace them seeing as they're almost 50 years old? As for listening, I think these are one of my favorite ARs, behind the -9. The tone controls are interesting on this one.

Thanks @Aadams! I’ll try adjusting angle as I keep testing.

My music room has recently changed. As I mentioned above, we live in an old house with mostly smaller rooms. We just finished an attic renovation and that’s where my listening space is now. I’ve been cycling through my collection of speakers in the new space…partly to get to experience them all there, but mostly to see what works best. I’ve tried the -9’s, -3a’s, (a new to me pair of) 10pi’s, and KLH Model Fives. Surprisingly, even though they’re the largest speakers, the -9’s to my ear still sound the best in that space. The bass goes low effortlessly but is clear and doesn’t boom. Granted, this is with the EQ recommendations mentioned in the manual. So my question is, what about the design of the -9’s allows them to work so well in less than optimum, smaller room settings? Picture is of the beauties in their new space. Distance between vertical arrays is just under 6ft.

Thanks for the offer and your prior advice, @genek. I know what I did wrong, I just need to practice more. I’ll post some pictures of that area when I’m ready to circle back around to working on these. For now I can hide the corner with the sand through against the wall and no one who comes in the room will be the wiser. Frankly I’m just glad the grills and grill cloth came out so nicely. I think those being so neat helps hide some of my shortcomings. I’ve been avoiding working with grills because I had very limited experience working with cloth. But this weekend I did these, a pair of AR- 4x’s, and I redid my AR-6’s. I feel confident enough that I’m going to redo my Model Fourteens with the leftover cloth I had from this project.

Well it’s been a few months but I finished the Fives today (for now anyway). My attempted touch ups of the sanded through areas….didn’t go so great. After a few attempts I ended up with a result that almost highlights those areas. It is what it is (for now). In the future I may sand through the varnish and reattempt touch ups. Thankfully those areas are small. I’ve learned that this hobby (for me) is very recursive; I’ll go back and fix mistakes once my skills have improved. As for the finish, I decided to use glossy spar varnish. It’s not true to what was on the veneers originally, but I think it makes the veneers pop. This was my first use of spar. I replaced all the caps and replaced the resistors with beefier 10w resistors as mentioned on this board. Resealed all the woofers and midrange drivers. The project concluded today when my wife and I made new grill frames and installed fabric. I haven’t wanted to play these speakers much because I’ve been afraid my toddler would push in dust caps without grills on. I used Guilford of Maine’s wheat colored acoustic fabric. It’s enough off white that it looks somewhat aged, but still very clean and bright. I moved my AR9’s out of my main listening area to install these. They’re less than have the size of 9’s but they’re far from half the sound. I really love these after only a few hours of critical listening. I can understand why someone in the 60s or 70s would have chosen these over AR-3a’s between the great sound, lower cost, and higher impedance. Beautiful speakers.

Hung them up today. I’ll touch up and paint the new rails soon. These are really fantastic little speakers. Not much bass of course, but upping the bass on my receiver’s tone controls a couple clicks makes me feel like I’m not missing much.

Looked around. Here's that same stamp on a vintage Swedish credenza I found on Etsy. So maybe KLH outsourced production of the 14 to Sweden?

I recently purchased 4 Model Fourteen S speakers and I have a question. tl;dr: How much of a benefit would there be to resealing the cloth surrounds on the Twelve Point Five drivers in the Model Fourteen S being that it's a ported speaker? So I bought four of these to run in my quad setup. We recently finished a remodel of our attic and I've been putting a music room back together in the new space. Before these, the only speakers that I owned two pairs of were AR-3a's which I ran in room briefly. Those speakers were far too much for the quad space which is roughly 11.5' x 9.5'. I read about the Model Fourteen S and thought they'd be a more suitable substitute for the space. I took them apart to recap them, and that's when I realized I would need to take off the grill cloth in order to get to the front of the drivers. Currently, all 8 Twelve Point Five drivers are working and the grill cloth on each speaker ranges from Good to Excellent. They sound very good as well...I hear no rattling or other noise and they all "sound" the same to me so far (although that could change as I get more time logged listening to them). All of that considered, is there good reason I should go ahead and reseal them as the Service Bulletin indicates? I understand the seal needing to be excellent in an acoustic suspension design, but does it matter as much since the Fourteen S is ported? Also, a couple of other things from taking these apart: At some point KLH eliminated the Compensated Amp input and left only screw terminals. Three of my four have the CA RCA jack while the one with the latest serial number (in the 7000s) only has screw terminals. Also, one each in the pairs I bought had a large stamp on the inside of the back plate which reads "Karlit Tempo" and "Made in Sweden." Was the back plate or its material made in Sweden? The whole speaker? The terminal plate of course says Cambridge, Mass. I'll post photos in the replies. Thanks in advance, George