JKent

Here's an old paper from North Creek the art of bypassing.pdf

I had the same experience when I rebuilt the crossovers in my Snells. Decided to give ECaps a try, since they had been recommended by some here. Mine are all about 10% over. Probably not audible but I expected better. IIRC Dayton electrolytics are usually spot on and cost less. No more ECaps for me. YMMV

New caps are smaller. The original is 2000uF, I think 35v. I sent you a 2200uF 50v. Physically smaller but correct. Check the old cap. One lead will be marked. Just be sure to observe the same polarity when you replace it.

Yeah--the Models Five and Thirty-Three are very similar looking speakers. I can imagine a surround system with Fives in front and Thirty-Threes in back. I'm sure you noticed that the Thirty-Threes look a lot like your OLAs. But the finishes on those have not aged well. They're not oil or lacquer. I'm guessing varnish. A real dog to strip off but WELL worth the effort as Norman's photos can attest to. Before they were dull and kinda orange. After, the walnut veneer is stunning. Good job! What did you use for a finish? I used Minwax Antique Oil on mine but I think lacquer, poly or Watco oil would also work well.

Crossovers complete. The 32uF in the tweeter circuit is bypassed with a green Russian Paper-In-Oil 0.01 cap.

Beautiful

You're welcome The original weather stripping was applied around the perimeter of the back of the cabinet. That's very narrow so I fing it much easier to apply it to the removable back panel. Use thin foam weatherstripping like this https://www.amazon.com/gp/product/B000BQRQA0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1. Should be available in hardware stores. Don't use Mortite. It's too thick and it will glue the back panel on so you'll never get it off again. Also weatherstrip around the panel with jacks and power cord. And add a little piece to the ends of the dowels that are attached to the back panel The filter cap is VERY easy to replace. I'll send you one. Just remember it's polarized, unlike speaker caps, so be sure to follow the polarization. I don't remember where I found the woven vinyl placemat but it's a good substitute.

Hi Norman I've restored several Twenty-Ones, so I'll try to answer your questions. Yes--it's early, in the sense that KLH made 5 different radios, all called Twenty-One. Your version was first. First pic below shows 4 of them. I don't believe that specific knob was used on anything else. I have one for you. The cabinet has to be airtight. The speaker is the ubiquitous "Twelve point Five" used as a mid in the Twelve and Five speakers and full range in the 8, 11, 13, 14, 15, 19, 21 and others. KLH recommended re-doping (Roy's goo). You will have to put thin weatherstripping (like 1/8") around the perimeter on the back. Easiest wy is to put it on the back panel. Also around that area where the jacks and power cord are. I assume you have the "potato sack" stuffing. I don't know about difficult. I have the service manual if you want. I always replace the 2000uF filter cap just because it's very easy and will prevent 60 cycle hum from developing any time soon. Your refinishing sounds good. You can't. I've had some success removing it, cutting and pasting. I've also used a woven vinyl placemat. You "could" use cloth but it won't look authentic. The 2nd pic shows original on the bottom, vinyl mat on top (but I don't remember where I got it). Third pic shows the cut-and-paste almost finished. Kent

Hi Richard To me that looks like some sort of physical damage, not electrical. Nevertheless, I'd say definitely replace them and IMHO you may as well go with a higher rating. Those are 8.2 Ohm, 7 watt wirewound. Brand is Expotus (any brand is OK). As long as you're at it, I'd go with 10-ish watts. I'm here in the US but some Brit members have mentioned Falcon Acoustics. https://www.falconacoustics.co.uk/ls35a-kit-falcon-minimonitor-q7-systems/resistors-ceramic-wire-wound-metal-oxide-loudspeaker-crossover-network.html Mouser (UK) is another resource. Any of these 8.2 ohm 10w wirewound resistors should work: https://www.mouser.co.uk/c/passive-components/resistors/wirewound-resistors/?power rating=10 W&resistance=8.2 Ohms&termination style=Axial|~Solder Lug I broadened the search a bit here to include 8 to 8.25 Ohms (close enough IMHO) and 10-12.5w. https://www.mouser.co.uk/c/passive-components/resistors/wirewound-resistors/?power rating=10 W~~12.5 W&resistance=8 Ohms~~8.25 Ohms&termination style=Axial|~Solder Lug&rp=passive-components%2Fresistors%2Fwirewound-resistors|~Power Rating|~Resistance They (Falcon) stock Expotus but I don't know if they have 8.2 ohms. Maybe give them a call. In the meantime maybe another Brit will give some advice. Kent

I dunno. I'm not familiar with it either so the OP can take both our comments with a grain of salt but I believe the writer on AK who said the amp has a switch for 4-16 ohms was mistaken. The back of the amp has speaker binding posts marked 8-16 ohms. I looked at the manual and could only find references to 8 or 16 ohm loads. The amp is a beast and very cool looking. It's a professional PA amp and apparently robust. It does have protection circuitry that will kick in if the load drops below 2.5 ohms but given the age of the amp and the 8 ohm rating I'd go with Aadams's advice. Why take risks with AR-90s?

Agree. AND the P2200 seems to be rated for 8 or 16 ohms. 8 ohm speakers could be trouble.

Well, my E-caps came today. First impression: I'm not impressed (let the flames begin 😊). They're NPEs made in Germany with a +/-5% tolerance. I put my bundles together and here's how they measure: 56+33+10 "should" be 99uF. These measure 109 and 109.2. So more like 10% off 22+10 (+0.068 a PIO bypass cap) should be 32.068, measure 35.5 & 35.6. Again, about 10% 10+2 (the 2.0 is a Dayton film cap and measured spot on) measured 13.3 & 13.4. About 10% again. And it ain't the Daytons throwing it off. Can't comment on how they "sound" but I'm a real skeptic about that. NPEs from PE probably would have measured better. I know a 10% variance in capacitor value is considered perfectly acceptable but when you're going for "premium" or "audiophile" caps it's disappointing. Changed my mind about the resistors (again) because I don't like the amateurish-looking layout of the xo. Waiting for new 25w Rs from Mouser. While I wait I'll probably re-dope the tweeter domes. I've read some discussion of refurbishing the coated silk domes ranging from smearing on Permatex to completely disassembling the tweeters, removing all the original coating and painting with shellac. I plan to use Roy's cloth surround goo.

And I did. Even though they are consecutive serial numbers, one had a bundle of three 33uF caps while the other had a single 100uF. I ended up ordering slightly different value Ecaps. For the 12uF I'll use 10 (+ a 2uF film cap I have on hand). For the 32 I'll use a 22 + a 10 and for the 99 I'll use 56 + 33 + 10. Haven't made a decision about bypass caps but am open to comments. As I mentioned, there's another bundle in there (lower right hand corner in photo above) but they're film so I'll leave them alone. Also decided to keep the original 25w resistors. If that's the original design it may not be wise to downgrade to 20w. Got my order from Simply Speakers today and re-refoamed them. They certainly look better. We'll see how they sound. SS sells surrounds specifically for these Snell Euro Vifa M21WN woofers. They're slightly smaller than generic 8". They also claim the surrounds are made in the USA. A bit pricier than some at $42/pair but worth it if they are an exact fit. The kit comes with nitrile-based adhesive, which I hate so I used Aleene's Tacky Glue. The cones are treated paper.

Thanks for that research. I was struck by the statement "While the company continued to manufacture speaker systems for decades after its founder’s death [in 1961], it essentially became a me-too brand, building speakers that offered solid value but uninspiring performance: the audio equivalent of, say, Buick". I'd agree with that assessment. A Buick tag line of old was "Wouldn't you really rather have a Buick?". Um, no. But a Buick is still a perfectly good car and I'd say the same of the '66 Jensens.

Finished evrything but the grilles. Ordered some 3/16" MDF from Michaels online. The sheets are "almost" the perfect size. I think I need 10 x 19" and the ones I ordered are 10 x 20". One respected speaker expert said Jensens were "pretty crappy". I disagree, mostly. The cabinets are very well made, with nice walnut veneer. I don't like the way the grille/baffle was attached and they don't seem 100% airtight. The woofer is a nice 8" cloth-surround Alnico job but not as nice as AR's. The tweeter is a pretty generic 3". Crossover seems appropriate with 2 caps, 2 inductors and a level control. Speaker terminals are crappy screws. I banged the baffles out and trimmed them down to fit inside the cabinet, recessed about 1/4". Made cleats to go around the perimeter to glue the baffles to. I didn't cut the baffles absolutely perfectly, but had some black Phenoseal on hand and that filled the gaps. The veneer was in very good shape (except, inexplicably, for 3 screw holes along the long side of one speaker). I just did a light sanding (220) and then applied 2 coats of wipe-on poly. I may do more with that. Painted the baffles black. When reinstalling the drivers I tossed the tweeter's paper "gasket" and used the caulk from PE. Tried to also use that on the woofer but the studs are so short there was no room for more thickness, so I just torqued the nuts down and hoped the layered paper gasket would work. Hit a snag when putting the woofers in. The cleats got in the way a little. Trusty ol' Dremel fixed that 😉. The xo is attached to the back panel so a little bit of a juggling act attaching the leads, replacing the fiberglass and reattaching the back panel. The panel is held on with 8 wood screws so I added some thin weatherstripping to try to make the best seal. Added Daka-Ware knobs to the level controls (either the knobs were missing or they were never there). So I've been auditioning them. Listened to them as a stereo pair but also played several selections in mono, switching between 1 Jensen and 1 AR-4x. They're similar designs and of the same era so this seemed like the best comparison. The Jensens don't have the perceived bass that the ARs have, and although they have similar woofers the ARs have a longer throw and are "looser". Neither the AR nor the Jensens do very well with the 3-finger test but the ARs were apparently designed that way, with their porous dust caps. Despite their second-place comparison to the ARs, the Jensens sound very good to me. Placement in my shop is not ideal. They're far out from the wall and much too close together but the initial impression is that these are very listenable speakers. I listened to a variety of vocal and instrumental CDs as well as a test CD. Everything sounded good, including some favorite recordings that I've listened to hundreds of times. Low-frequency isn't AR but it's good. Likewise dispersion isn't AR. But these would be good speakers in a smaller room. When I get a chance I'll take the ARs off the shelf and put these up there to give a fairer listen. I imagine the bass will improve.

Looking for some input here. Haven't decided yet whether to tackle the buzzing woofer myself but I pulled one crossover today. Snell was known for "bundling" capacitors as can be seen here. I'm not going to bother with the film bundle, lower right but there are 3 NPE bundles I think I'll replace. Snell originally used NPEs in those spots. That may have been a purely financial decision but I've been wanting to try the Mundorf E-Caps so I thought I'd stick with NPEs rather than film. Here's what's in there now: 4+8uF (12uF) 2x16uF (32uF) 3x33uF (99uF) Looking at what's available in the E-Cap line at Parts Conexion, I plan to order these: 10uF + 2uF 22uF + 10uF 3 x 33uF Sound good? I also thought I'd replace the old sandcast resistors. They are 4 ohm 5% 25w 0.5 ohm 5% 25w Mundorf MR series resistors: 2 x 8.2 ohm 2% 10w (= 4.1 ohm 20w) 2 x 1 ohm 2% 10w (= 0.5 ohm 20w) Or I could use Mills. They have 8 ohm and 1 ohm, 1% tolerance 12w. That would give me exact values at 24w BUT they're $9.50 each (so close to $80) compared to Mundorf $3 each. Or there's Riedon 50w with the finned aluminum enclosures but they may be physically too big. Any other ideas?

Thanks David. I know the original owner and he said he only re-foamed the woofers. I will however be looking at the xo's

For free! A neighbor was getting rid of them so right place/right time. I've never worked on Snells before and there's not a whole lot of info that I can find. So I fired these up and one sounded just wonderful. The other has an occasional buzz, which the neighbor had told me about. Apparently Snell advised against re-foaming and instead tried to sell customers entire new woofers AND crossovers (!) when the foam rotted. My neighbor, being a sensible guy decided that was ridiculous and decided to re-foam the woofers himself. Unfortunately, that was not his strength. So both woofers look bad and one makes a "raspberries" sound sometimes. Otherwise they're in great shape. I think the cone is poly (edit: they’re coated paper) and the new foams were attached with the nitrile based glue, so although I've refoamed a lot of drivers I'm a little hesitant about this. Will update when I've made progress. Hope there are still some Snell guys around to give advice! Kent

Started on them today. They have a kinda cool '60s grille but one is torn so the cloth will have to be replaced. Unfortunately, the cloth is wrapped around the front baffle and the baffle is glued and nailed in place. Access is through the back. The panel is attached with screws around the perimeter and it comes off easily. Not much obvious effort to make these airtight. There's no sealant or gasket for the back panel and the drivers have cardboard gaskets. Only about 1/8" taller than my 4x's, otherwise the same size. Stuffed with fiberglass. The crossover has a level control pot for the tweeter, 2 inductors, a 17uF cap and a 2.7uF cap. The caps were the infamously leakage-prone black Callins jobs with red ends but amazingly (to me) the ones I removed from the first speaker measured spot on. The smaller inductor was positioned INSIDE the large one! And they're held in place with twist ties and wide electrical tape. I used parts I had on hand: 2.7uF mylar film and for the 17uF, two 8uF NPEs and a 1uF poly. A pic of the rebuilt xo is below. I moved the small inductor as far as I could from the big one. The drivers were easily removed. They're held to the baffle with 4 machine screw studs and kep nuts. But removing the baffle was another matter! Once the xo and drivers were removed I used the brute force method: Hammer and a block of wood (note to self: Next time, less brutish). So I managed to break the particleboard baffle but I'm gluing it back together. I don't want to apply the new grille cloth the same way. It's virtually impossible to remove and I don't care for the way the grille/baffle protrudes from the frame. So I think I'll trim the baffle so it fits inside the cabinet, then recess it a little. The rabbet around the front is only about 1/4" deep so I'll make new grille frames out of 1/4" Masonite or, if I can find it, 3/16" MDF.

Picked up a pair at a local yard sale. I've heard of the Jensen name but can't find a thing on the web except a 1966 ad. Haven't listened yet or opened them but they're roughly the size of my AR-4x's. Nice walnut veneer. 2-way. 8" alnico woofer. 3" tweeter. Acoustic suspension, I believe. Made in Chicago. photo shows the Jensens with my "ARvid" speakers--Avid 100 guts in AR-4x cabinet. The Jensens may appear bigger because of the bigger grille. Anybody know anything about these?

Good luck with the restoration. I’m sure you know about Human Speakers but just in case…… https://www.humanspeakers.com/e/epi50.htm

John, I certainly respect and understand your desire to set up your shop. Not necessary for a simple re-foam but satisfying in its own right. And summer certainly offers other sources of enjoyment. On the subject of glue, PVA (white glue) works perfectly on foam. I buy my surrounds from SpeakerWorks. They offer both types of adhesive and you can read about them here: https://www.speakerworks.com/SearchResults.asp?Search=glue&Submit=. White glue is very easy to use and very forgiving. Cleans up easily with water, can also be thinned with water and is non-toxic. Many speaker manufacturers use it. Nitrile-based adhesive OTOH is smelly, toxic, and very unforgiving. If you are a meticulous worker you "can" use it on paper cones but why go through the hassle? When I press a surround into the glue on a cone some inevitably oozes out. With white glue it's easily wiped off (I just use my finger) and cleaned with a damp rag. The nitrile-based stuff is much more difficult to use. Think Elmer's glue vs contact cement. Literally thousands (hundreds of thousands?) of DIYers have used white glue on foam surrounds for paper cone drivers. Adhesion is not an issue. Kent

Well, I’ll be reevaluating the Zilch/PeteB modded Minis. I just finished a second pair and discovered a problem so I tore both pair apart and will report on the results soon. Will probably compare the ARs, Zilch mini 7, modded Zilch mini 7 and some Zaph HiVi single driver minis

Jab, I've been following this and I think you think re-foaming is much more complicated than it is. It's really very simple and you don't need a well-equipped shop, just a table. You've said you don't plan to shim (btw, I always shim) so it may be even simpler. And you don't need a lot of tools or supplies: an X-Acto knife, some alcohol, maybe a few small clamps or clothespins. One word of advice: DON'T USE THAT AWFUL SOLVENT-BASED GLUE IN THE SIMPLY SPEAKERS KIT. Plain ol' white glue works. Aleene's Tacky Glue is perfect but may not be available in Italy. White glue works. It can be spread with your finger. It cleans up with water. And it's very forgiving--if you make a mistake just pull it apart before the glue sets, wash it off and try again. The solvent-based glue is necessary if you have a plastic cone but it is not needed for paper cones and it is very likely to produce terrible results. ...just my 2 cents. Kent

Don't ruin your woofers. Roy's sealant available from Vintage-AR is the only thing that is true to the original and will never harden.