JKent

Or try spraying on the Blue Coral while the cloth is still on. Staples won't puncture if you use Roy's method with thin wood strips or cut the staples. I have not tried Gorilla fabric glue (may be worth a try). I use Aleene's Tacky Glue. Kent

I agree completely with Roy but would add a couple of thoughts: Since you know where to get new cloth, why not give cleaning a shot? Gluing thin wood strips works well but one member (again, I forget who it was) said he took his strips of 1/4" staples and using some scissors cut a little off the legs. I haven't tried this myself but it sounds like a solution. btw, for thin frames like those on the KLH, you don't really "need" an electric staple gun. An Arrow T-50 works fine. I have both, and on some old frames even the electric needs to be really pushed down on hard. Kent

Nice work! One member here (sorry, I forgot who) had good success with Blue Coral DC22 Upholstery Cleaner Dri-Clean Plus. Those KLH grilles can be tricky because of the layer of black scrim behind the cloth. I don't know if it might bleed through if you spray the top fabric. Might be worth a try. I'd vacuum the grilles first.

Hi Anthony I'm about to start working on my own 4x's that I purchased new in 1969: SN FX262692 & FX262765. This will actually be my 2nd restoration job on these and I "think" they had about 18oz. of fiberglass (haven't opened them lately) and #5 inductor coils. I recently bought a pair of cabinets with no drivers: SN 368908 and 368196. They still had the original stuffing and crossovers and both of those had approximately 12 oz. of clumpy yellow fiberglass. Many years ago our friend John O'Hanlon (editor of the AR-3a restoration guide) wrote: "Roy C. and I have been comparing notes on AR-4x details. It would appear that early AR-4x, say before about serial 290,xxx (mid-to-late 1969), used AR-#4 inductor (0.88 mH) and contained 17 oz fiberglass stuffing. The later AR-4x used AR-#5 inductor (1.2 mH) and 11 oz of fiberglass stuffing." A recent exchange with Roy he told me earlier speakers had 17-20oz. of fiberglass while later ones (after SN 293977) had 11 or 12 oz. Apparently the engineers at AR had decided the 4x was over-damped and reduced the amount of fg. I will put 11 oz. in mine. btw, the precise weight does not seem to matter much but based on Roy's expertise I'd suggest taking out 6-8oz from each cabinet. Kent

I put this on the auction site but if someone here wants it please PM me. Sorry. SOLD

Yes, butyl. Temporary brain fart. This is the KLH Service Bulletin: http://www.classicspeakerpages.net/library/klh/other/klh_schematicsservice/klh_service_bulletin_60.pdf Thank you. I went back and corrected my error. I had referenced the Service Bulletin but clearly did not re-read it! Obviously, I'm not a chemist. But a quick Google search showed that butyl is synthetic, not natural. What difference does it make? I have no idea. Just sayin' it seems wise to stick with the tried and true (and original). People have put all kinds of weird stuff (latex caulk for example) as well as "seemingly" appropriate stuff (Permatex) on their cloth surrounds with disastrous effects. I would only use what the Service Bulletin recommends.

The dope is for cloth surrounds--not foam. The KLH Service Bulletin in our Library instructed repair centers to always re-dope all KLH cloth-surround drivers. I can tell you from experience the application of the correct dope made a night & day difference on my KLH Model Fives. Yes, and that thread wound up in the Kitchen. The sealant Roy cooks up is authentic butyl-based (the stuff KLH and AR used) and has been available for a few years from Vintage_AR on ebay or directly from Roy on this site. IMHO it is unwise to put anything else on our valuable speakers.

This was my 3rd lot of 100 pieces (actually 120 this time around). Each time I say I'm not doing it again but within about 3 weeks I've sold more than 80 so I guess there's still a demand. Only about 32 (16 pair) left.

That's an impressive collection of AR-7s! I'd be interested to see a closeup of the Italian crossovers. A tip regarding your photo space: Try resizing all photos to about 100KB each. Kent

In my living room system, if I don't want the full surround-sound for music, I have a Harman-Kardon T-60 turntable with Shure V-15V cartridge feeding a re-capped and fully refurbished Scott 299 tube amp and a switch that lets me play those through the Cizeks. A little vintage setup within the HT. As an aside, I bought the HK TT new back in the 80s to replace my AR XA. It seemed to be essentially an AR but with auto-lift, a nice Itok tone arm and a few other niceties. Doesn't have the vintage charm of the AR so I'm glad I kept that, too.

Thanks. Got one. And thanks to Larry for offering.

This discussion is sort of veering off in a couple of directions but I'll add my 2 cents: I've been a fan of subs for years but they are controversial and some purists reject them out of hand. I don't currently use a sub with the AR-91s or 3a's but in my living room (aka home theater) I have a surround system consisting of nearly 100% vintage speakers. The main front speakers are Cizek KA-1s, with 6.5" woofers so in that system I use a whopping big sub. It's a VMPS Original with a 12" woofer and 15" passive radiator, built from a kit years ago. It was originally passive but I added a plate amp a few years back. The HT uses a modern receiver with Audyssey which is great because it sets the levels of all the different speakers in the mix, including the sub, so they play nice together.

That's a tough one. I've never been good at describing the sound of speakers or the taste of Scotch, I just know what I like 😄 My first impression was that everything sounded more "here". Maybe more detailed? More life-like. Sort of like being in the room with the performers. I'll have to do more listening. OTOH, my listening room is far from ideal. The big 91s don't fit in my living room so I use them in my rec room-turned shop. I do think it's a synergy among the DB1A preamp, DB6A amp and the speakers. I don't yet have a 'table in that system but I do have a 2nd stereo in the shop that includes an AR TT, DB1A preamp and a Musical Concepts modded Hafler DH200 driving AR-3a's. I don't have the same you-are-there experience with that setup but those speakers are in a really bad location so not a good comparison at all.

I know "How Many Watts?" will be a subject of endless discussion here on CSP but I for one have had a change of heart. I was always of the mind that 12" ARs need mega power. I recently acquired a DB 6 amp, rated 60wpc into 4 ohms. I'll admit I'm kind of a DB "groupie" having admired the gear from this little New Hampshire company for decades but I had shied away from the amp because it seemed, well, underpowered. My new-to-me DB-6 was sold as "for repair" so I got a good buy and DB's founder/owner, David B (DB)Hadaway is still selling and repairing/upgrading DB gear so I sent him the amp for repair and upgrade to 6A. I'll write that up in the appropriate section of this forum but wanted to report that after replacing my Adcom GFP-565 preamp and GFA-555/II amp (325wpc @ 4 ohms) with a DB-1A preamp and DB-6A power amp, my AR-91s have never sounded so good! Granted, I'm not trying to fill a stadium (but who is?) and also not cranking it up to 11 (like Spinal Tap). Here's a paper from DB Systems, dated October 1978, that addresses the issue.

Hi Giorgio Funny thing about the Model Twenty speakers. I don't believe they originally had badges. But they do look better with KLH badges and I do have reproductions. I'll email you to discuss that. And I'm flattered you would put JKH badges on your speakers! As for the AR-4x speakers, here's the story: My first speakers were AR-4x, purchased new in 1970. About 20 years ago (maybe 2002) I replaced the grilles but they didn't look right. That's when I discovered CSP and our friend John O'Hanlon (editor of the AR-3a restoration guide) guided me through not only getting the right grille cloth but also rebuilding the crossovers--my first! A few years later Roy helped me modify the speakers by installing Avid 100 drivers and crossovers. The Avids may be superior to the ARs (let the flames begin) but they were in horrible, disgusting, putrid vinyl "wood grain" cabinets 🤮 But the drivers are drop-in replacements for the AR-4x cabinets and the cabinets are virtually the same volume. But now my AR-4x's are no longer. They're Avid 100s in nice cabinets. The ARs have strong sentimental value so I plan to restore the original drivers and will rebuild the crossovers with film caps and my new heavy-duty pots. So what to do with the Avid drivers and crossovers? When I saw empty AR-4x cabinets for sale I had to buy them! Aren't you glad you asked? 😄

Well, I toned down my criticism. Turns out when I looked at that seller's ads to find your single Twenty I saw he was also selling single AR-4x empty cabinets. Just what I was looking for! He accepted my offer for the pair (I made sure he understood I only wanted them as a pair) and he then recalculated the shipping cost to save me money. A good guy after all.

What a shame! I looked at the original ad and the seller also wrote "I will be listing another Model 20 soon." Who separates a pair of speakers and sells them individually? But I'm glad you can use your center speaker output and enjoy 3 Model Twenties.

Hi Giorgio. Congrats on the speaker purchase! I sent you some pictures privately but will also post them here for others who may want to work on some Twenties. One word of warning regarding your plan: If you put the screws through the aluminum plate you need to isolate them to avoid shorting. KLH solved that problem by using rubber washers--one shoulder washer and one flat washer. Kind of a nuisance. But as the last photo below shows, this is exactly what KLH did with the Twenty +. As an aside, I've been asked to restore a KLH Twenty + compact system. Very cool Mid Century Modern stuff. If I take that project on I'll post pictures. On my first Twenty restoration I added a terminal cup. But for that arrangement you should put caps over the RCA jack to maintain a sealed box. KLH used rubber caps on the unused jacks on the Model Twenty One radio but they usually got lost. I found some 5/16" screw protector caps in the local hardware store and those worked fine. I think the metric equivalent is 8mm. https://www.walmart.com/ip/Uxcell-5-16-inch-ID-Black-Screw-Thread-Protectors-Vinyl-End-Caps-20-Pack/751572364?wmlspartner=wlpa&selectedSellerId=571 On my 2nd Twenties I used a more elegant solution IMHO. I replaced the RCA jack with some dual binding posts like these: https://www.parts-express.com/Dual-Binding-Post-1-Red-1-Black-090-475 Fully insulated.

Oops. Thanks. I was thinking of the dual 3" Model Eight speakers I’ve been working on. It's been a whole since I worked on the 14, 15, 19 but I should have realized: The impedance of the series-wired dual driver early Eights is about 15 ohms so I should have known parallel would have made the speakers 4 ohms. Senility? Mad cow disease? Sorry Chris.

Or one from a smaller Advent

Some discussion here: And here's a thread that shows the nice frames Glenn made from 1x1 pine lARrrybody made some beautiful frames for me. If you are handy at woodworking you can some too. Or http://foamspeakergrilles.com will make foam reproductions. There "was" an ebay seller offering reproductions for $130/pair but I don't see them now. And I think there is information in one of our threads about making your own foam grilles.

Here's a handy reference: http://www.aphenos.net/electronics/speakers/klh/all_klh.htm The Fifteen, 14B and 19 were all the same. Two of the ubiquitous "Twelve point five" drivers with a port (!!). I've worked on a few but unfortunately I have no pics of the innerds and no notes. Here's a shot I pulled off the interweb. Pretty sure there's a filter network. The 2 drivers are each 8 ohms, wired in series. Kent

Personally I don’t treat the twelve point five surrounds

Anyone have an OLA tweeter like this for sale? Please PM

FWIW my tech always uses Panasonic caps for their quality and reliability. That blue cap is some cheapy I bought before learning better. 2200uF 35V is a good replacement and use a cap rated for at least 105°C