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In Reply to: Re: Horn Beauty Contest update. posted by Paul Eizik on July 24, 2005 at 15:35:57:
Hi AllJohn Wolf's Classic Audio Reproductions certainly deseve a mention here. They have been around for quite awhile. The first time I ever heard 300B SET's and horns together was with one of John's Hartsfield Reproductions way back at one of the late Larry Dupon's flea markets in the early 90's. John does some very fine woodwork. My Dad and I did a close up walk around on his then current rig at M.A.F. 2002, and were very impressed with the woodwork, and my Dad is a master carpenter. C.A.R. is a strong runner in the beauty pagent.
Paul
Follow Ups:
When these speakers appeard in the 90's, I thought that they were the strangest looking horns I'd ever seen. Today, compared to Josh's creations, they almost look kind of conservative. They still are quite striking though, and I've always liked them for this, though I'm sure others may hate them for the same reason. They got mixed reviews/comments at the time, and you never seem to hear anything about them anymore. I've never heard them, but always wanted to.Paul
Never heard them though
Has anyone?
SteveI guess (by your results) that Jadis isn't importing the Eurythmies anymore. BTW, a google search for the Yamamura Dionisio 27 by me turned up just 3 dead ends ( and I did spell it correctly this time ; ) I guess they too are extinct.
Too bad.
I guess (by your results) that Jadis isn't importing the Eurythmies anymore. BTW, a google search for the Yamamura Dionisio 27 by me turned up just 3 dead ends ( and I did spell it correctly this time ; ) I guess they too are extinct.Too bad.
Yeah. The only other photo I've found of the Dionisio is this worthless dark blob posted on the Dayton Wright website.
The photo I posted I scanned from an old copy of Hi-Fi+ which featured an interview with Be Yamamura (before he moved to Georgia and became Bo Yamamura ) and Robert(?) Churchill.
The Dayton Wright website did however feature this pair of Eurythmie 33s. Apparently the Eurythmies weren't made by Jadis, but by a company named A Il Ingeniere SA. Wasn't able to find anything about them on the web.
se
SteveB&W blob or not, the Dayton Wright pic is very interesting. In your color pic from Hi-Fi+, the driver is direct radiating on the front and horn loaded on the back, with the driver mounted in the horn mouth. In the variation in the B&W pic, the driver appears to be double loaded, with a small horn on the front in addition to the rear horn loading, and the driver plus small horn are mounted above the large horn mouth. This may seem like a minor detail, but it's not. In a back loaded horn (with front direct radiator) the throat of the back horn has to be "choked", that is to say made considerably smaller than what would be optimal for nominaly maximum sensitivity. This is necessary to keep the output from the back horn from over powering the direct radiator front output. The driver does look like it's been mounted further towards the mouth where the cross section of the horn is larger (the section of "elephant trunk" seems missing from the big horn mouth), so the designer(s) were aware of all this. It looks like the small mid-range horn has a built-in toe-in (it appears that the example in the pic is a left channel). Anyway (as usual) Harry Olson has been there, done that back in 1936. Perhaps Yammamura and Churchill picked up a copy of Acoustical Engineering in Georgia.
I remember the same pic of the Eurythmie 33 too, the text looks like it's in Dutch. I don't think any 33's made it to the USA. Ya gotta hand it to these guys, they were aestheticly fearless! Audio commandos like Eurythmie paved the way for the kind of things Josh and the rest of us are doing.
Thanks for the Mystery Pic!
Veddy interesting, Paul. In Harry Olson's relatively small monitor of the 1930s and 1940s (RCA 64A, 64B), his dual voice coil 8" full range driver radiates directly from the front, while low frequencies are produced by loading the driver with a rear horn. The horn has complex folding, and approximates an exponential horn with a series of progressively larger straight pipe segments.When I obtained a couple of these, I noticed that the horn is "necked down" severely in two locations as the horn progresses. The bass horn output seems somewhat shy in comparison to the front radiation. I've been tempted to open up the restrictions, but hesitate to perform surgery on these rarities. The restrictions are not shown in his drawings of the design, yet they appear in the production pieces. Olson may have done this to avoid too much boomin' bass in a small control room setting.
SteveYou are the only person I've spoken to whose actually seen one of these rarities from the age of the W.E. (and later the Altec) monopolies. The chapter in Acoustical Engineering does'nt mention the dual voice coil with the double loader as I recall. My speakers, which are derived from the Mellow Monster design from the 1962 Popular Electronics magazine, is quite similar except that the Mell. Mon. originally used no horn on the front of the driver (i.e. nominally a "W" manifold on the back of the driver followed by an "S" into the horn mouth). I put them together in the late70's, and promptly lost interest for several years. My Dad lost the plans for a while too, so I later resorted to using an electronic stud finder and chalk to outline the partitions which worked out pretty good. My version has areas where the expansion goes big rather than being restricted. Attempts to smooth these areas out made no difference in measurements of the freq. response, much to my consternation at the time. What made a vast difference was enlarging the throat area to something a bit closer to the Sr of the EV15B, and later drasticly increasing the area of the rear horn mouth. Most people would look in horror at the flat sided 180 degree bends in the "W", but they serve a "muffler function" and limit the output of the rear horn over nominally 180 Hz. like Olson's graphs show. An interesting design that got steamrolled by by the other big guys, and resists design by computer and the numbers nowadays.
Hi Paul,Harry Olson designed at least two back loaded horns that used the symmetrical fan folding of pipe segments on either side of the driver, then progressing downward into a merged forward, back, forward and out path in the cabinet bottom.
The smaller design was used in the 64 series monitors, sold mostly into radio station control rooms. It featured direct radiation from the front of the cone, and used several angled sheet metal vertical deflectors to disperse high frequencies. The 64A and B used different drivers, but both were variations on the 6" cone, 8" basket theme of the early Photophone drivers, and both used his ingenious dual voice coil.
There was a larger system that loaded the front of the cone with a rectangular straight exponential horn. It was sold as a Photophone system for smaller theatre installations in the mid 1930s. I'm not sure which driver was used in this one (never seen one of these), or whether it used the dual voice coil, but I could probably look it up in the old literature.
Olson was one whale of a horn designer. He is credited with inventing the W bin and recommending its use to the MGM Shearer team. I have also seen drawings of back horns where he utilized cavities on either side of the beginning of the horn path behind the driver. These cavities had small, apparently tuned openings into the horn to allow the absorption of high frequency energy and keep it from being propagated by the horn. Similar goal to the fan folds, different execution.
I've never seen the Mellow Monster; I'll have to be on the lookout for that article.
Hi allYamamura made a lot of different variations on this theme,
all of them slightly different . He also used a homemade fullrange driver, with a very trick suspension.The text under the Eurythmie 33 is in Danish,
stating among other things that the speaker is made of formpresed wood.cheers
Thanks for the info Jan!Very little information is available on the 33's. The photos are evidence that at least one pair was built. I wonder where they are now, and how they sound?
Thanks, Paul!I was going to offer those up but I couldn't remember what they were called. Went to Jadis' website and came up empty.
se
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