walsh tweeter design/rebuild

loquatious

village elder
edit: while at the time this thread was started, i had yet to own a pair of walsh-equipped infinitys, i subsequently became the owner of a pair of infinity monitor IIa speakers that utilize the walsh super tweeter. they are keepers. it should also be noted that this thread was started when a gentleman who purported to have been involved in the building of the prototypes of the infinity walsh tweeter was asked to elaborate on the process for the infinity faithful here at AK. that person later turned out not to be as advertised. nevertheless, for those interested in the walsh tweeter, it's design, restoration, and repair will find much valuable info in the pages that follow, if you are willing to wade through them. end edit.


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i don't own any infinitys that employed the "walsh" tweeter, but i've always lusted after a pair. i try to be an educated shopper, so i try to seek out info on the tweeters because, on most speakers i see come up for sale, the walsh tweeters are either thrashed or missing. i know replacements just don't come up, and the ohm company won't service the infinity derived version of the walsh design.

in my internet wanderings i came across an interesting thread relating to the walsh tweeter by a guy who built the prototypes for infinity. he goes by the handle "glorocks," but his name is jay and he seems willing to share info on how to build or rebuild a walsh tweeter. its on another site (diyaudio), but it contains some interesting info i thought would be useful to the infinity faithful. the thread is fairly recent (as of this writing) and seems to be in danger of petering out. i'd encourage members of AK's infinity forum to jump in and encourage this guy. he tried a thread on audiogon and had no interest, so he went to diyaudio. maybe we could coax him over to AK?

thought i should pass this on.


http://www.diyaudio.com/forums/planars-exotics/207762-diy-walsh-driver-revisited.html


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Interesting.

The linked photo of the refilled (refoamed?) Walsh tweeter in the DIY thread is mine - one of a number of good Walsh's I have refoamed.

I have three Infinity speaker models in service with Walsh tweeters, Monitor IIa's, 2000II's, and WTLC's, and have probably 10 or 12 loose drivers, some of them working for spares and some not. I have also deconstructed a couple to see how fixable they might be and have determined that even though most had the open at the point where the wire travels from the VC to one of the terminals, my chances of repairing them was slim to none. The voice coil wire is so thin that it seems getting anywhere near one with a soldering iron even at a very low heat would cause them to go up in a puff of smoke. Add to that the fact that I can barely even see the wire let alone manipulate it to attempt to remove a winding and reconnect the lead. I basically gave up on the idea of repairing them.

I still have the deconstructed units somewhere and would be happy to take photos if they would help with this project.
 
i found the audiogon thread. it gets pushed in the direction of the ohm drivers because they are not much of an infinity crowd over there, but a few more bits of info on the infinitys come to light:

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1330482547&openusid&zzGlorocks&4&5


as i said, i don't have experience with these tweeters first hand, but they don't seem like rocket science. my take on this was if jay was able to build 50 or more of the tweeters on his kitchen table, he must know something about how to go about fixing them. and since he's willing and able to tell how it was done, others could do it too. he indicates it was not too complicated, and technology/materials have only improved over time. at the very least, jay/glorocks seems like a valuable source of information (even if it is only historical). just need to let him know there is interest.

just a thought, if the wire is too delicate to be soldered, what about using electrically conductive epoxy like that used in circuit board construction for heat sensitive parts?



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A soldering iron is not going to melt copper or aluminum. Whether you can manipulate it is another matter, if it is too fine to see.
 
i'll have to suggest that, since someone did the wiring to begin with, it can be seen and manipulated.

if there is a will, there is a way. nothing ventured, nothing gained, and all that, right? besides, if the tweeters don't work anyway, whats to lose by trying?

a soldering iron will melt ultra-fine wire if you are not careful. at least mine will. thats why i mentioned conductive epoxy as an option to consider.

i don't know how thin the wire in the tweeter is, but i just did a repair (with a soldering iron) on the wiring in my AR XA turntable's tonearm. talk about tiny wire. that tonearm is wired with awg 34 single-strand anodized copper magnet wire, as thin as a human hair (.0063). to complicate things, it was inside a 1/4" diameter aluminum tube with 3 other agw 34 wires next to it, and had to have the anodizing scraped off before soldering.

it was a challenge for sure, but i managed it with a strong light, a jewelers' magnifying glass, a hemostat, exacto knife, and a big ol' heapin' helpin' of patience. had to use nail polish to re-insulate the join when finished, but it got the job done and the XA is back in action.

i'm 55 years old and i'm blind in one eye and have no depth perception. i have to think, if i can manage that kind of detail work, so could most people. i don't know, but it doesn't seem to me like the tweeter wire repair could be any harder than that tonearm job was. i'd be interested in seeing detail pictures of the problem areas and the wires in question. perhaps splicing in a length of magnet wire is an approach, not necessitating unwinding a full coil?

i always thought the cones would be the problem area. most i've seen look severely crumpled and looked to be, i assumed, beyond repair.

still, if you could really build a new one (on the kitchen table)...


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I was not suggesting that the repair is impossible but beyond my expertise and physical ability to actually perform the work. Certainly if repairing these Walsh's was easy somebody would be making a lot of money doing it. I think the only time I've read of one being repaired by the method I mentioned earlier, unwinding one winding from the VC to allow reconnection of the wire to the terminal, I remember that the writer mentioned that the tech who did the work said he would not attempt to do another one.

I'm 71 and although my eyes are still pretty good with the help of double cataract surgery, my hands are just not steady enough to do such delicate work which is why I offered to provide photos of the drivers that I have taken apart as my contribution to the discussion. I remember that even taking them apart was made difficult because of the way the magnet was attached so that removing it provided more than ample opportunity to cause even greater damage to the driver than may already have been present.

It's true that the cones are often damaged because they are so fragile and the loss of the supporting foam makes them even more suseptible to physical damage and I wouldn't even bother with those, but even with a pair that look perfect, the VC's are very often open.

I'll see if I can locate the disassembled drivers and take some photos to post.
 
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Certainly if repairing these Walsh's was easy somebody would be making a lot of money doing it.

exactly. there is somebody doing it. if you go on ebay and do a search for walsh tweeter repair you will see. i have no connection or experience with him and am not promoting his service. i only mention this because his claims indicate not only that repair is possible, but it can't be that hard to learn how. as for making a lot of money, i'd agree you could probably charge a pretty penny, but i don't think you'd ever get rich because the market is so limited.

as i mentioned, i don't have any speakers that use this tweeter (yet). if and when i do, i assume a repair will be in order. i only started this thread to let people know the original builder of the tweeters, who should be a great resource, was available and seemed willing to help people who were interested. i'm not promoting a service. i like the idea you can fix things yourself. i do, however appreciate, that not everyone wants to, or can, do it themselves.

even though it is called the "walsh" tweeter, lincoln walsh didn't build, or design, it. neither did ohm, which is why they won't have anything to do with it. true walsh drivers were/are full range drivers (actually midrange) that required supplemental drivers to extend their frequency response even to cover the range of human hearing. if you go to ohm's web site and look at the spec's, you'll see none of the walsh speakers can produce over 20,000 hz, and many, including the famous F, peak at only 17,000hz. they aren't that efficient either. the walsh's true virtue is its imaging.

typical of infinity, their "walsh" tweeter went well above 20,000hz. iv'e seen it spec'ed as high as 28,000hz. that's getting close to emit territory.

it seems the "walsh" tweeter infinity used was designed, trial and error, by jay painter (glorocks) and bill seneca, and may only be called a "walsh" because it was using walsh's principals (and the name "walsh" had some marketing value as an exotic technology). at any rate, it seems like having a living resource like jay who is willing to share can only be a good thing. whether people want to make use of that resource is up to them.

bill watkins is still alive, and is available to ask about the watkins woofer. arnie nudel is still alive, but not talking about the past much (and i don't see him participating in forums, or giving out his phone number). use a resource, or don't, but once these guys are gone, they are gone. i just wish the guy actually responsible for the development of the emit tweeter prototypes would make himself available. i'd like to hear his stories.



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There has been some controversy on AudioKarma regarding the vendor offering the Walsh Tweeter repair on eBay such that I don't think I would consider availing myself of his services, but maybe that's just me.

The information regarding the Walsh tweeter that I've always taken as gospel is what Infinity provided which was that "this new WTLT tweeter was developed and manufactured by Infinity under license from Ohm Acoustics, and is a newly engineered extension of the Walsh patent No. 3424873", and that Infinity stopped using it when they developed the EMIT so as to avoid the licensing costs. Here's the original patent for the widely recognized inverted driver:

http://www.google.de/patents?id=E55SAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

I've found no record of the patent extension that Infinity sites so I guess it's anybody's guess if Arnie Nudell isn't talking.
 
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i know there is controversy surrounding that vendor, and don't think i'd personally do business with him myself, if only because of his ego. i just sited him as someone who actually is offering a rebuild service, and because he said it only took him 2 days to figure out how to do it.

well, i can't speak of gospel...

i think infinty's marketing statements should be taken as such. marketing, that is.

my inclination is to believe that infinity needed license from ohm simply to make use of the walsh name for marketing purposes. the infinity walsh was a single layer embossed aluminum cone glued to a voice coil, and it did propagate a wave in a similar manner. but it was not an inverted driver and did not seem to follow any of the specifics of walsh's design parameters regarding cone material, size, shape, or taper. sounds like the motor was different as well. if you compare a real walsh driver to the one infinity used there are more differences than similarities. also if you talk to the head of ohm, he really doesn't know much about the infinity walsh. in fact he told me he'd never even seen one until someone sent him one a few years ago.

if the infinity "walsh" was indeed developed by 2 guys at a kitchen table using exacto knives, epoxy, and aluminum foil, and cutting up someone else's tweeter for a driver, then it doesn't sound like ohm was involved in it's "development" at all. lincoln walsh was dead at that point, so he wasn't involved, and actually, it doesn't sound like infinity was very hands-on in the process either, though they may have been financially involved. these are questions jay would probably be able to answer.

in reading the walsh patent, i noticed right away much of the text is lifted from edgar vilchur's patents. (vilchur was the inventor of the acoustic suspension speaker, and designer of the AR speakers and turntable). i find that interesting. several others seemed to "contribute" to the text of that document as well ( of course when you are applying for a patent, you want it as wordy as possible).

another interesting thing to me is infinity didn't fully move away from the walsh tweeter before the emit came out, but i'm not clear as to what the exact time line was. what i've read is confusing. i've read the WTLC had a production run from 1976 to 1981. if that is true, the walsh was produced concurrently with the emit for a few years. but the the WTLC was also superseded in in infinity's hierarchy in 1976 by the column II which used 2 piezoelectric tweeters. again, its marketing copy, but in infinity's literature of the time they state the column II represents "a brilliant advancement, both acoustically and cosmetically, of the famed W.T.L.C." this indicates to me they felt the piezo was a superior tweeter, as the rest of the column II design was basically the same as the WTLC. that, and the column II cost more than the WTLC.

again, i've never heard a walsh tweeter equipped infinity, but i do have a pair of column IIs which i just restored (mine were originally purchased in '76). they are a very good speaker, but i can't say i see (hear) anything really spectacular from the piezos. at least nothing like i get from my infinitys with emits. as far as i know, the first speakers with an emit were the quantums which i've read first appeared in 1978. i'd like to see infinity's full line catalogs of the period to establish a proper time line, product hierarchy ,and production overlap.

btw, you can see the column ii document i quoted in post #140 of this thread:

http://mail.audiokarma.org/forums/showthread.php?t=383980&page=10

why infinity turned away from the walsh, i can't say. perhaps cost of manufacturing killed it. the piezos were pieces from peerless, but infinity claimed they were specially "hand treated" so who knows how they stacked up price wise. i think there is evidence the walsh was such a fragile tweeter, that that may have contributed to its demise. from what i've read, apparently production of the walsh stopped before the licensing from ohm ran out. it was in use, as was the piezo, at the same time as the early emits, so they each must have targeted a different consumer price point. the POS was in production at that time too, and used yet another tweeter.

lots of factors come into play when you are a manufacturer. for example, as good of a reputation as infinity's polypropylene cone woofers had, the next generation of injection molded graphite cones were superior. yet that IMG technology was dropped because HK wanted a lower manufacturing cost, and polypropylene was cheaper. they killed the emit for similar reasons.


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I am very interested I building/ rebuilding walshes, I just got a pair of 2000 axt I have in another thread. I've had the wtlc for a while and had great luck with my walshes, my new 2000's have one which is half or less working but not totally dead, erich I have never heard of before, it measures at 1.0-1.6 ohms and the sound is really quiet, I iv course measured it with the Walsh totally removed.
 
when i first started this thread, i'd sent a PM to jay (glorocks) over at the diyaudio site and and invited him over here to AK. he has graciously agreed to share info and insights with us and is now a member of AK. since jay helped developed the prototype walsh tweeters infinity used, this is a rare opportunity to ask questions and get first hand knowledge from someone who was there. whether he wants to chime in on this thread, or start his own, i don't know yet, but let's welcome him to AK and the infinity loudspeaker forum. its good to have you here jay!


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Hello, loquatious asked me drop by and maybe answer some quesions. By the way, L, thanks for the build up. It wasn't that big of a deal-
J
 
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Welcome to AK.

Any information you can provide regarding Infinity's use of the WTL tweeter in the Monitor series (less the Jr.), 2000II's, 2000AXT's, and WTLC's would be appreciated, especially the aspect of the licensing of the design of the driver from Ohm and the reasons for discontinuing it's use. Of course I am also interested in any info about the engineering and creation of the driver and your opinion about the real world reality of repairing them.

Thanks in advance for any light you can shine on what has always been a rarely discussed part of Infinity's history but one that holds a certain fascination for me as a big fan of the Walsh equipped mid-70's Infinity's.
 
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hi jay,

thanks so much for this opportunity. i have a lot of questions. for starters, it would be interesting to know something of your background. how you hooked up with bill, and got involved with infinity and the walsh tweeter project. i'd be interested in what year it was you started working on the project, how much input infinity had, ohm had, etc. how much time was spent on the prototypes before it actually went into production. how the process proceeded in terms of trial and error, that kind of thing.


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Welcome to AK Jay!
While my Infinitys have the EMITs, I look forward to hearing about the Walsh drivers from you.
 
Welcome to AK!
I'm interested in what we can do to rebuild the Walsh, or how can we make new ones.

Just the other day I talked to someone who owned a speaker shop in the early nineties and he told me that towards the end of Walsh production when he would order one it was produced badly and he had to rebuild it before being able to install it. So I'm interested in what model phases there were in the Walsh history.
 
So I'm interested in what model phases there were in the Walsh history.

i agree. i think it would be interesting to document the variations in the design as it evolved through production, the models those variants were used on, and the years those models were produced. those of you who are owners might want to post pics.

a couple of these just sold on ebay. i'd never seen this version with the external support (as opposed to the center tube). i'm thinking it was early production, as it uses the same diamond tufted reynolds aluminum foil for the cone that jay had described using for the prototypes. that cone looks pretty sturdy compared to others i've seen. monitor II was the model infinity these tweets came from according to the auction description. the exoskeleton support would seem to offer more protection of the delicate cone. wonder why that was changed.


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I have both versions, the external support version on the 2000AXT and the rod support version on the WTlC. Here is a picture of my freshly refoamed rod version. I missed that auction as I would have paid that for a working replacement for the blown one in my 2000axt

fe9dfb47.jpg
 
Hi- My name is Jay, and as some of you know, I was involved in the early prototyping of the Walsh tweeter which Infinity adopted just prior to the introduction of the emit.
I want to make it clear that I can't help you fix your tweeters. I can only tell you how they came about, and what went in to the original prototypes. I have no knowledge of what Infinity did with them after the prototypes. I had to get a real job.
Perhaps, however after reading this, you may find the wherewithall to attempt to build your own.
In 1972, I landed a job with the local Hi-Fi "salon", and met Bill. Bill was the local hi-fi guru and was and still is well ahead if his time in all things high fidelity.
Back then, there were two US Hi-Fi factions. East coast, which included Ed Vilchur and Henry Kloss, (Advent, KLH, and AR) and West coast which included Phil Coelho (ESS) and Arnie Nudal (Infinity). The west coast sound was primarily based on a 2" Peerless tweeter that sounded good, and was very cheap. (emphasis: cheap) Both companies dabbled with exotics, such as the Infinity 2000, and the Transtatic (ESS). Neither of their "full range" exotics were succesful.
The only truly hi fidelity speakers were full range electrostatics. KLH produced the Model 9, and Peter Walker did the ubiquitous ESL 57, which in my opinion was one of the stellar hi fidelity achievements of the 20th century.
About that time, Marty Gersten of Ohm Acoustics introduced the Ohm A, based on Lincoln Walsh's classic theories.
One of our more affluent freinds bought a pair of Ohm A's and we were all invited to listen. We were floored- never had we heard anything as well defined or coherent before.
About three weeks after we heard Mauro's Ohm F's, Bill walked into the store with this thing that looked like a small bird cage wrapped in foam. The first Walsh tweeter. It had a 6dB shunt crossover that you could hook to your exsisting speakers, much like you would a passive subwoofer. There was an unmistakable "air" to the highs, but it was shrill and grainy.
Bill showed up again two days later and took it back. He then showed up a week or so later with another unit, and this time, it sounded amazing.
What had happened was he started using viscous dampening materials to tame the resonance peaks, which plague all Walsh drivers. In theory, Lincoln Walsh's dream was extremely elegant, but in practice, it was a nighmare of peaks and resonances, which is why all of you find yourselves with tweeters that are covered with various foams and goos that have long since hardened. I'll ge to this later.
At this point, I want to stress that the idea was Bill's. I was only an interested bystander until he needed help filling orders. I also want to stress that Bill is no longer the least bit interested in this tweeter, and if any of you try to find him, my dialog here will end. Bill is still my freind, and is very private. Please respect this.
I am going to end this here for now. Tomorrow, I will discuss how the originals were built, including the parts, materials and techniques involved. Again, I must make it clear that I can't/won't help you fix your tweeter. I can only guide you in making your own.
Thanks for listening-
J
 
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