JKent

Finished! Here is a shot of the insides, labeled. The 6 screw holes on the lid were filled with epoxy and reinforced with small strips of scrap wood, then redrilled. The Velcro strips on the bottoms had to be removed to remove the plywood, so new Velcro was installed. Also added an extra strip across the top (these hang on the back of each speaker) to help support the added weight. The Clarity cap in the center was originally installed with a cable tie but the mounting block added too much height, so now it is stuck on with double-sided foam tape. I have never put much stock in esoteric caps--no golden ears here--but my Twelves with these upgraded xo boxes sound great! Hard to do a real A/B comparison, but subjectively I think they sound better than they did with the mylar caps, and they also seem to sound better than my AR2ax + VMPS sub setup. YMMV. Switches were sprayed with De-Oxit and the screw terminals in the back got a little dielectric grease. Will send these back to Rob (if I can part with them ) Kent edit: the 2.7uF is mislabeled as 3.7

Apparently just getting warmed up. If you go back to post #34 you can see Rob's three pair of Model Twelve contour boxes, with a mix of no-name film caps and some NPEs for the 50uF caps. Here is the re-do of pair #2. Rob wanted all high-quality film caps. The selection was based on two considerations: Quality and physical size. Here's what we used in each box: 1) 2.7uF Auricap (original value 3uF) 3) 4uF Auricaps 1) 15uF Clarity Cap PX (original value 16uF) 2) 50uF Dayton film & foil polypro Also replaced all the resistors with new Mills 12w non-inductive resistors. Fitting the 50uF Daytons was the biggest challenge. Thought I'd have to "raise the roof" of the contour box or put the caps outboard, but by cutting away part of the 1/2" plywood base inside the box, it provided just enough room. Also had to shift some of the inductors and tie points slightly. Photos below show the contour box before the "first" recap, the plywood base notched to accept the Daytons, and the finished contour box. One finished, one to go. Kent

Hi Carl Sorry-no. But Rob loves them. Maybe he will comment here. Kent

I had some reproduction KLH labels made. They're aluminum, and pretty good copies. Shown here. I can also get the larger KLH, but they will also be stick-on aluminum--not cast. Also AR logos in solid shiny brass or satin brass, large (for 1,2,3 and small (for TT, 4) Also have some solid brass "3"s and "a"s Dynaco and Advent too. Sorry--no 3a plates Questions? email KLHbyJKH@gmail.com Kent edit: PRICES VARY SO CONTACT ME. ALL ARE UNDER $10 EACH. SOME ARE $5. edit: New photos. Please scroll down to Post #14 edit: AR and Dynaco logos are solid brass

Hi Rob Of course my 1st thought is "your incompetent technician screwed up one contour box" but you said it used to work, then stopped, so maybe something did blow out. Since you have at least 3 pair of boxes, I guess you're OK for now. Actually, I did not replace the resistors (see the photo in post #34). Only replaced ones that were obviously scorched. Probably should have just replaced them all, like I did in your Fives but the common wisdom is "wire wound resistors don't go bad." Guess if you've SEEN some scorched 5-watt resistors your opinion should change! Putting the Clarity Caps in the Twelves will be a challenge but it could be fun too. It may just be a matter of "raising the roof" on the boxes--making them taller. A little carpentry job. You might also consider firing that bum tech. The way I hear it, he's a retired psychologist with absolutely no credentials in electronics Kent

One thing worth mentioning again--be sure to examine all of the resistors for scorching or cracking, and replace as needed. If I were doing this again I would probably just replace all of the 5w resistors with 10w. YMMV. Kent

With a LOT of help from Roy, I just modded my original AR4x's (bought new in 1969) with Avid 100 drivers. As Roy said, simple drop-in replacements and nicer construction. Why not use the original Avid cabinets? The plague of the '70s--"wood grain vinyl" Finished the job with new Irish Linen cloth as described in the AR3a manual. New metal logo plates from Vintage AR replaced the tarnished originals. I had just one plastic AVID logo, so it's glued to the baffle to show the true nature of these speakers. Initial listening seemed to show more/lower bass and more high-end detail than the 4x (mine were previously restored, with new L-pads and Zen caps). More listening within the next few days. Thanks Roy! Kent

Hi Tekker and welcome RoyC will get back to you regarding his experience with replacement tweeters. He has done a LOT of research and I believe he has had very good results with inexpensive HiVi tweets, but I'll let him address that. Partsexpress has Dayton caps, which many people like, but caps are sort of a religion and you will get many conflicting opinions. The originals were non-polarized electrolytics and therefore cheap NPEs should work just fine, but film caps will last much longer, and as I said many people will debate the relative merits of different caps endlessly. PE has some real nice Mills resistors, or their standard Dayton line. The recognized expert on rebuilding speaker drivers is Bill LeGall at Millersound but as I said, wait to hear from Roy. His HiVi solution may be perfect for you (or in the meantime check out this thread, especially page 2): http://www.classicspeakerpages.net/IP.Boar...eeter&st=20 good luck Kent

Maybe, but I'll stick with natural fiber because it shrinks. Apply it to the frame as best you can, spritz, dry. Voila! Nice n taut. Kent

Some thoughts on grille cloth: Years ago I replaced the cloth on my AR 4x’s with brown burlap. Looked fine but it is not acoustically transparent. When I removed the grilles it sounded much better. Irish Linen looks authentic on vintage speakers and it has good acoustic transparency. Michael’s craft stores sell a couple of suitable fabrics. If you go to their website and sign up, they will send you a 40% off coupon almost every week. The Charles Craft Irish Linen sold at Michael’s in “Tea” color used to be just about perfect for AR speakers but it has changed—both the color and weave—so you have to look at it and see if it is right for you. I think it is 28 count. With 40% off, it is cheap. Michael’s also has Zweigart “Cashel” Raw linen, 28 count, 18” x 28”. It is not exactly the right color but it is quite attractive and again, use the coupon. Also at Michael’s: MCG Textiles Belgium Linen, 32 count. Color is similar to the Zweigart but 32 count is a bit too fine. OTOH you may like it (and use the coupon) I bought some rug hooking cloth online: MCG Textiles “Linen Burlap”. It looks nice but I think that, like the regular burlap, it may be too heavy. The 1-2-3 Stitch linen referenced in the AR 3a restoration guide ( http://www.classicspeakerpages.net/library...ring_the_ar-3a/ page 17) is very nice but a little expensive. The “lambswool” color is a bit light for the OLAs but it is a good quality fabric with an open weave (18 count) and a nice heft. It is made by Wichelt and I see that it comes in other colors, so you may find one that is closer to the original (or how about Wild Raspberry?) http://www.123stitch.com/cgi-perl/abcSearch/search.cgi Looking at the fabric I have on hand, and my OLAs, I’m guessing the OLA cloth is coarser than 18 count. Maybe 14 or 16. Carl is right of course—the OLA had a sheer black backing layer, like some KLHs, Rectilinears, etc. BUT I would hesitate to put another layer of fabric on the grille. IMHO they will look fine and sound less muffled with a single layer of lightweight fabric. So get the fabric of your choice. You can attach it with Allene’s Tacky glue, then spritz it with water and dry with a hairdryer (see p. 5 of my KLH Eight manual: http://www.classicspeakerpages.net/library...lh_model_eight/ Good luck! Kent

Welcome to CSP! One option: Vintage-AR sells the cloth with complete instructions. Members who have done this will probably give you other options. Kent

Probably more dramatic with a smaller speaker, such as the Four, Five or Six. Here's a copy of the brochure pages, dated 1979. Kent

here's the inside

As many New England speaker fans know, before Henry Kloss met Ed Vilchur and convinced him to go into manufacturing acoustic suspension speakers (since no one would buy the idea ), Henry built cabinets for Baruch-Lang loudspeakers in his Cambridge loft to support himself while he went to school. According to a 1952 Popular Science article: http://books.google.com/books?id=SiEDAAAAM...lt#PRA3-PA71,M1 "Just by drilling holes in the cabinet, two sound engineers have made an acoustic unit using cheap, small speakers sound as good as a costly big job. The holes do the trick by "tuning" the cabinet and baffle to compensate for inadequacies in the four 5" speakers. Calculating the hole size was so complicated that an electronic computer was used to figure it out, report the inventors, Dr. Jordan J. Baruch and Henry C. Lang of Massachusetts Institute of Technology. Dr. Baruch and Lang say their unit, with two watts of amplifier output, reproduces the tonal range and volume of a full symphony orchestra. It is said to be "flat" (accurately imitating the original loudness) over a frequency range of 40 to 11,000 cycles, which covers most tones audible to the human ear. The Baruch-Lang speaker, small enough to fit on an end table, promises to bring out the full quality which is inherent in FM radio and TV sound, but which now is often distorted by inadequate speakers. It will be marketed by Ultrasonic Corp., Cambridge, Mass., for less than $30." These speakers were sold mail-order as well as locally in Cambridge. The basic speaker cost $25 "in a handsome, mahogany veneer cabinet--in your choice of four modern decorator finishes to blend with every decor." And for $30 you could get the "Deluxe Model" "with a handsome frame and grill for added beauty. Available in the same luxury finishes...Blonde Modern, Rich Mahogany, Chinese Black and Natural Unfinished." see the attached pdf file--it's an ad from Audio mag I recently bought one, in nice condition, although the backs and sides are flat black painted plywood, so I don't know if this was modified or came as a utility version. I hooked it up to a 1960 Henry Kloss KLH Model Eight radio and it sounds surprisingly good. CSP member and KLH historian Andrew Hayden has written briefly about this speaker, noting it would be interesting to replace the 4 drivers with later KLH full-range speakers that were used in the later Model Eights, but I think this speaker is pretty nice "as is." [Andy--if you follow this thread please comment]. An interesting piece of audio history! Kent Baruch_Lang.pdf

Hi Carl and welcome! A request--could you post a higher resolution copy of the second attachment? I just bought a pair of Sound Windows (SW!) and am eagerly awaiting their arrival! Kent

Thanks once again for all the info Pete. The Aura will fit, but it is 4 ohms while the RS original and the MCM are 8 ohms. The other specs seem to differ also, but I don't know if those differences are important. What's your advice here? Kent oops--I see there is an 8 ohm version of the Aura as well. Is that the one ou mean? http://www.madisound.com/catalog/PDF/ns4-255-8f.pdf

Pete, While you had the mini 7 apart, did you happen to measure the physical dimensions of the woof? The MCM 1853 is: Dimensions: •Overall frame diameter: 4.13" (pincushion) •Required cutout: 3.66" •Mounting depth: 2.80" Kent

My ebay Mini 7s arrived today. Nice walnut veneer and the grilles are intact. I had a couple of Sprague 5uF film caps from a previous project, so I pulled the xovers, removed the 4.7uF NPEs and installed the Spragues, then shoehorned the things back together. The cap "just" fit thru the hole in the cabinet, then I pushed ti aside to clear the woofer. These little guys sound good! And for a real treat, I ran them AND my AR2ax's. Nice. The Mini 7s are temporarily on top of a stack of other speakers, so they happen to be at ear level. I think they enhance the ARs. I may leave them as is or perhaps later use the SB mod. Kent

Thanks again Pete Kent

Thanks Pete Actually, I did see that thread but did not know if that was the SB mod, and I was wary of the schematics because some contributers had noted errors. Maybe I'll just replace the 4.7uF caps with some 5uF film caps I have on hand. If you ever dig up that SB article maybe you could post it here. I had some Mini 7s--used them as rear speakers for years, then sold them on ebay. Just bought another pair, with walnut cabs, so I'd like to play with them a bit. Kent

Thanks for the info Pete. Do you (or any other member) have info on the mods that were recommended in Speaker Builder? I know there is a fellow on ebay selling kits, but I'd rather build my own. Looks like it involves some caps and an inductor. One Minimus 7 enthusiast recommended just replacing the 4.7uF cap and adding more stuffing, but I'm curious about the full-blown mod. Kent

Anyone know anything about these: Model 402 speakers, Model 450S receiver? The speakers are 2-way AS in plastic cabinets. Look like the big brothers to the 400 and I guess they were available with the Model 402 radio (post-Kloss) and must have also been sold separately. Anyone know any more than that? Are they any good? I can't find ANY info on the 450S receiver. Pretty unimpressive looking and I'm guessing also post-Henry. But I can't find anything about it. Anybody familiar with these? Thanks Kent

My first stereo was a kit-built dynaco ST-35 amp, a KLH tuner and some 'phones. Later added a PAT-4 and ST-120, along with AR TT and AR4x. I still have the speakers, TT and tuner. The 'phones were discarded and all the dynaco stuff went on ebay. Made a few bucks on the ST-35 Last week I bought a dead ST-120 on ebay to practice my electronics skills (limited) on. I've ordered the 5 big "can" capacitors--they cost more than I spent on the amp! We'll see how it goes. If successful, the amp may replace the AR amp in my vintage system. Kent

Finished!

Thanks Carl! Here's one xover with Clarity Caps completed. I used "Goop" instead of RTV because it's stronger, and had to add the Masonite flange because one mounting hole in the aluminum flange is somewhat inaccessible under the big caps. Kent