JKent

[Looks good! Correction on the Model Twenty-One. There were FIVE similarly-named radios: The Twenty-One was FM only and had a walnut veneer cabinet. The Twenty-One/II was essentially identical but the knobs were changed grom beige to black and the grille was changed from beige plastic to black cloth. Then there came three vinyl-clad models from the Singer era(early 70s): The Twenty-One FM, the Twenty-One AM/FM, and the Twenty-One CL (clock radio). Attached is a photo of a 21/II and a 21 FM. The AM/FM looked just like the FM. The CL was bigger. Left to right below, that's a 21/II, a 21 FM (not original foam grille) and a CL pic from somewhere on the web. Kent

Hi Vern Thank you for the compliments and your comments. Yes--I had not noticed the wafers on the switches, but there is a difference between my all-npe xover and the mylar/npe one I just finished. Also did not notice the penciled SN on the plywood, but now that you mentioned it, the xovers that have the "brown wafer" switches are marked in pencil "#240" and "#263." I did not see numbers on the "white wafer switch" plywood. There was a date, hard to read (Sept something) and I see I covered it with Goop to glue down the caps Interesting note on CR's take on the Twelves vs AR3a's. I don't think the Twelves get the respect they deserve! They are essentially identical to the well-regarded Fives, but with bigger cabinets so they go deeper. That asset is also a liability. edit: The Twelves use different woofers than the Fives. Twelve woofers have double magnets. I bought mine for $100 with local pickup, and that included a KLH Eighteen tuner and an old speaker selector switch! Only problems with the Twelves were: Missing 3 knobs, terrible sound because of bad caps, a few minor nicks and scratches, tired-looking grille cloth. They now sound great with the new caps. I'm in the process of refinishing the cabinets and patching the veneer in a couple of places. Not sure what to do about the grille cloth. I have the metal logos but have not reinstalled them yet. Your comments about the paucity of KLHs in your neck of the woods is interesting. Of course, in New England they were very common. I notice a lot of Dynaco speakers on ebay come from Canada. Guess Dynaco did a better jo of marketing up North! Yes--the speakers are sometimes sold without the crossovers. Hard to imagine, unless buyers are opting for external electronic crossovers. Expensive, but probably nice. As I mentioned, I plan to sell one pair of crossovers (don't need two!) so I hope I can recoup the cost of the caps and knobs. Originally I had bought some nice inexpensive retro-style knobs in Rat Shack (shown in one of my previous posts), since 3 of the originals were missing. But the second pair had (only) 3 original knobs, so now I have one complete set! Could have used that schematic! Maybe then I would have bought the right number (and value) of caps! Here's a photo of one Twelve. Not finished yet. The xover was moved for the photo but is normally attached to the back with Velcro. More work to do on the finish. New cloth needed. Reinstall logos. Too bad these are in the hall OUTSIDE my rec room! Kent

So--Here is the completed crossover with the Madisound caps listed above. I'm burning them in now. Could not use polys for the 50uF caps, so I went with NPEs. Any NPE should fit. THANKS RoyC for all your guidance! BTW-- I STILL can't count right. You only need two 8uF caps OR one 16uF per crossover, so the count above should be FOUR 8uF caps (not 6). Sorry I seriously doubt I'll hear any difference between the mylars and the NPEs. Will try to sell one pair of crossovers (probably the first pair with all NPEs) when these are finished. Kent

OK--just placed my order with Madisound. Here's what I'm using: 2) 50uF Bennic NPEs (they are the only 50s that will fit in the box) 6) 8uF Carli mylars (for the 8s and the 16s) 6) 3uF surplus mylars (for the 3s and the 4s) 4) 1uF Carli mylars (to add to the 3s to make 4s) I'll post photos when this is finished. Kent

Bottom feeder: Here's another consideration (Roy just alerted me to): The convenient external crossover boxes for the Twelves have limited room. I figure any component (cap) placed inside can have a maximum diameter of about 1.25" The big 50uF polypropylene caps won't fit! Solens are about 1.77" diam and Daytons are about 1.5" Those big guys would fit INSIDE speaker cabinets, where there's lots of room, but not so the external crossover box. So it's back to NPEs Kent

btw--check the "Library" section here and dig down thru the AR section to the "original Models" section, then the "schematics/service" section to the AR 3a restoration document (too bad it is buried!). You will find a lot of useful info there on restoring classic speakers, even tho yours are KLH Twelves. Well worth looking at! (RoyC, who responded to your post, was one of the authors). Good luck and ask questions as you go along. I'm still working on my Twelves. Big monsters, but I love them! Kent

Actually, the more I think about it, I may very well go with electrolytics. They are closer in sound to the originals, and for the 2 crossovers we're looking at about $10 worth of NPEs vs $100 worth of polypros. Even if the polys sounded better (debatable) I'm sure they don't sound TEN TIMES better! Think I just talked myself out of the Solens.

Hi and congrats on the Twelves. I was watching that auction, too. I think the Twelves are GREAT speakers! Amazing they don't fetch better prices. I'd love to hear an A/B comparison with AR3a's. I bet the Twelves would hold their own! You're right--I did use run-of-the-mill NPEs. The speakers sounded terrible when I bought them, now they sound wonderful. I also have a pair of MicroStatic supertweeters sitting on top--not sure if they are necessary but the whole system sings! Of course, never willing to leave well enough alone, I just bought another pair of external crossovers and am planning to rebuild these with better quality Solens or Daytons, with advice from xover guru Roy C. One quirk with these--they used some dual-value caps and in some cases the dual-values were soldered to the same points. So you don't need 11 caps per xover, only 7. The attached photo is labeled. It shows 11 NPEs. When I bought the speakers I did not have a schematic, so I just counted all the caps Counting the dual as 2 each, there were 11. But after disassembling I discovered most of the duals were doubled up so, fo example, a dual 4uF had both red leads soldered to a common point, making it a single 8uF. I've labeled the attached photo to reflect that, except that the two dual 4uFs actually all go to the same point, making the value 16uF (not two 8uFs as shown in the photo). SO: Your parts list for EACH xover is: 2) 50uF 1) 16uF 3) 4uF 1) 3uF Of course you will have to buy double those amounts to do the two xovers. I also replaced all the wire wound resistors, which in retrospect was totally unnecessary and I do not think I'll do that with the next pair of xovers. edit: I now think it IS necessary. The original resistors are only 5w and I've seen some burned ones. My advice: Use 10w. The NPEs work fine and they are very cheap. PartsExpress has them (in some cases the values are just slightly off--I think the 3uF caps are really 3.3). For my next crack at it I'll use polypropylene caps from either PartsExpress or Madisound. PE has most of the values in their Dayton line, but the 16s will have to be Solens. At Madisound I think most of the values were available in the Solen line, except the 16 (oddly enough) so you'd have to go with Bennic. It's my understanding you can go a little over or under in the cap value. Then there are tricks of using small "bypass" caps on the tweeter circuits and adding small resistors in series with the polypro caps to smooth them out and make them mimic the old electrolytics. This is all a little beyond me! Frankly, your best bet may be to use 105 degree C NPE caps and not fool around with all this other stuff Restoring the cainets will be another interesting chore. It's been written about quite a bit. And what do you plan to do with the grille cloth? That's 2-layer. Boucle over sheer black. Mine's a little tired looking. Yours looks worse. I'm thinking either Irish Linen like that used on the AR3a or maybe even black knit "speaker cloth." Add a pair of cast metal KLH logos and you're in business! Good luck! Kent

I'm thinking "other." Don't know how many avid AVID fans are out there

AVID was around in the 70s and yes--they were in RI. Model numbers were 100, 102, 104 probably a couple others. 2-way AS design. Check this thread: http://audiokarma.org/forums/showthread.ph...;highlight=avid cheers Kent

Andy! You're the man for the concise history!

> >Any chance please of a rear magnet photo of your OEM Advent >woofer/ fullrange driver. Look about 6 messages up on this page. I have a shot of the backs of the OEM and the Philips. The OEM is just stamped with the date Kent

Here it is. Pretty ordinary-looking. No inverted roll surround. I assume the Advent 5.25" Mini from AB Tech is essentially similar. Kent

AB Tech sells an Advent replacement that resembles the original: http://www.abtechservices.com/adventspeakers.html I'll take a photo when I can Kent

Vern, here is an original Advent driver and a comparison of the Advent (top) and Philips (bottom). The Advent had a 4-bolt mounting pattern, the Philips 8. The Philips is mounted on an aluminum adaptor plate. btw--what was the "well known speaker that was highly praised in it's day"? Kent

Interesting. I see there is a single Advent 400 speaker on ebay now and it appears to have the same driver. Was that a standard replacement? The aluminum adaptor plate appears to be manufactured--not a DIY Here's the link to the ebay item http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...:MEWA:IT&ih=019

Hi again Vern Based on your info, I found this page where the Philips AD5061/M8 is described. As follows: Philips 5" (128mm)* paper cone full range drivers with 2 3/16" (55mm) whizzer cone -- this is terminated with a flat ring which helps reduce whizzer resonances. 8 ohms (DCR=6.9 ohm). Voice Coil is 1" (25mm). It has the trademark octaganol 8-legged stamped basket. Drivers have cloth surrounds. I have brushed away the deteriorated open-cel foam that was used for a rear mount gasket. http://homepage.mac.com/planet10/vintage-d...allery/philips/ On another site, the author had this to say: For the rear drivers, I tried full-range Philips AD5061/M8, but they were not of high enough quality, power, or sensitivity. An album of Carmina Burana, with its lush chorus, has so much out-of-phase material I was getting distortion from the amp trying to drive them, and the small speakers were bottoming out. I replaced them with two of the same dome midrange drivers PMT51) I used for the front. http://www.rawsound.com/articles/MSspeaker/ Finally, these comments: The new midrange driver mentioned by Carlos Bauza as now being used in the Rectilinear HIis the Philips AD5061/M8, which Rectilinear is selling for $11.75. This unit is a high-compliance version of the earlier AD5060/M8 and may be had for $5.95 plus postage and $0.30 handling feefrom McGee Radio, 1901 McGee Street, Kansas City, Missouri 64108. The 5061/M8 is lessefficient than the old 5060/M8 and sounds worse. http://www.bostonaudiosociety.org/pdf/bass...112-760809b.pdf So not exactly rave reviews. Still, for the radio it seemed fine to me. Didn’t know what a “whizzer cone” was, so I looked that up, too: Whizzer Cone A small supplementary cone attached to the voice coil of a speaker for the purpose of producing and radiating high frequency content more effectively than the larger speaker cone. A whizzer cone is attached to the voice coil in the same place as the speaker cone; however, where whizzer cones are used it is necessary for there to be some additional flexibility in the joint between the speaker cone in the voice coil. This allows the speaker cone to become somewhat decoupled from the higher frequency motion of the voice coil so it doesn't dampen the voice coil from being able to move the whizzer cone at those higher rates. Whizzer cones have fallen out of popularity in the last couple of decades, mostly due to the added coloration of the signal produced by the necessary slop in the coupling between the speaker cone and voice coil. http://www.sweetwater.com/expert-center/gl.../t--WhizzerCone

Thanks Vern for the informative reply. Do you suppose this is a suitable full-range radio speaker? The KLH midrange was used as a full-range in KLH radios, so by that logic I'm thinking this should be OK. Kent

I opened up an Advent 400 speaker and found that the driver has been replaced. Sounds fine. The new driver is stamped "Made in Belgium" Here are pics of the back and front. Guess it's a coaxial design. Anyone know what it is? Thanks for any help.

Interesting--the green and yellow on my 4x are consistent with the diagram

Never heard of KLH Research Ten speakers. What are they?

funny how these threads are strung together. I made my hot cross buns observation before all the helpful info from John. You still got a deal on the drivers. 2 woofers you can use and 2 tweets to sell. Heck, you may even come out ahead! ;-) Kent

Great buy on those drivers Rick! I'm curious about the "hot cross buns" pattern on the woofers. I have a pair of KLH 33s with that pattern. Think it was to add damping to the woofer. But I have not come across it on my 3 pair of 4x's. Good luck with your restoration. You have some good advice from John and Roy--both have given me expert guidance with my restorations. btw--I put Zen caps in my first AR4x restoration (John's recommendation), but they are no longer available and were pretty expensive. My next restoration will use Carlis (Roy's recommendation) from Madisound. Clean those pots! It's not hard, just takes patience and elbow grease. Use a little deoxit or electrolytic grease to keep them working. Good luck!

Yes--watch ebay. These come up from time to time. You want a 2-way tweeter that is from any of the following Allison models: AL110; AL 115; AL120; A4; A5; A6; A7; CD6; CD7; PB 8.2; PB 66.2 (this is from the Allison website you checked). Be aware though, that there was apparently an evolution in those tweets. My A4s have tweets with delicate leads attached to brass binding posts, and exposed dustcovers that get crushed easily. Other tweets had lugs instead of leads, and others had lugs and heavy metal mesh over the tweet (there is a pair like this on ebay now). Another possibility is to replace the pair. I bought a pair of Audax tweeters from Madisound to use in an A4, but later found the "correct" parts. I bought the 4-ohm Audax Model TW025A2, the 8-ohm is TWO25A0. Purisists would probably not approve of the replacement, but these are good--they were used in the legendary Spica T50. And they were only about $22 ea. :-) Finally, I just sent off some dead tweeters today to Human speakers. Huw is going to check them out to see if he can either repair Allison tweets or manufacture suitable replacements. Stay tuned.....

you know it's odd. If you check the Allison site: http://www.allisonacoustics.com/parts.html they show that the 2-way tweeter AND the 3-way tweeter are replacements for the A4 and A5. But not ALL the speakers are listed under both 2-way and 3-way. How can this be? As far as I know, the (only) difference between the Four and Five is that the Four used two matched tweeters, while the Five was the "budget" version, using only one.