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Thread: Lansing discovery- WHOA!

  1. #1
    Senior Member Steve Schell's Avatar
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    Lansing discovery- WHOA!

    Yesterday I set up a pair of Lansing Iconics to listen to in stereo for the first time. I have blathered on about this in another thread:

    http://audioheritage.org/vbulletin/s...ad.php?t=16911

    At one point a slight buzz was evident in the high frequency driver of the left speaker. This Iconic is the oldest one I have seen, and uses the early style dividing network (serial #70) as pictured in the Lansing Iconic bulletin of 1937:

    http://www.lansingheritage.org/image...lletins/4b.jpg

    Anyway, I swapped out the 801 driver for another one and set the buzzing one aside for later inspection. This morning my friend Robert (who was collecting Lansing field coil stuff before I ever heard of it) took the ailing driver out to the shop to disassemble it. Shortly after, he ran into the house proclaiming a major discovery... this 801 has a radial slit phasing plug!

    Considering the history of the Lansing drivers, this discovery actually makes sense. Jim Lansing had been warned by Western Electric (probably in 1936 or 1937) that his 284 large format compression driver (developed for the MGM Shearer Horn) was being built in violation of their patent on the circumferential slit phasing plug. W.E. was apparently beginning to produce their 594A at the time, a 4" diaphragm driver based closely on E.C. Wente's U.S. Patent #2,037,187. Lansing had his engineer Dr. John Blackburn seek a solution to this dilemma. Blackburn designed a 20 slit radial phasing plug for the large driver and it continued on otherwise unchanged as the model 285.

    The Lansing Iconic was introduced in 1937; the earliest ad we have seen appeared in October of that year:

    http://www.lansingheritage.org/image...lectronics.jpg

    On September 1st, 1937 Western Electric signed a consent decree with the government to cease the supply and servicing of sound systems in theatres in the U.S. This evidently relieved Jim Lansing of the threat of legal action, and he soon resumed manufacture of his large format driver with circumferential phasing plug, calling it the 284B.

    I had always wondered why the Lansing Bulletin on the Iconic referred to the high frequency driver as an 801, yet almost every example I have seen is labeled 801B. I believe that we now have the answer. Both large and small format drivers were likely converted to circumferential slit phasing plugs as soon as the threat of litigation was removed.

    Unfortunately the label from this historic 801 was crudely removed by someone long ago, but it would have had a low serial number judging from the dividing network fitted to the same system. Another unusual feature is the rear cap, which was formed from heavy copper sheet and chrome plated. Most 801Bs have a painted cap which was formed from thinner aluminum sheet. Some later Altec era 801Bs have a die cast cap with the star pattern, as also seen on the field coil Altec 601 Duplex and early 604 Duplex.

    The Lansing 801 is the direct ancestor of all the later Altec and JBL 1.75" diaphragm small format compression drivers. We now have evidence that the earliest commercially produced version used a 14 section radial slit phasing plug. Wow!
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    RIP 2010 scott fitlin's Avatar
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    Great find! Your amazing Steve.

    Ive learned much more about really old audio from you than anyone or anywhere else!

    BTW, WHAT do those drivers sound like?
    scottyj

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    Senior Member louped garouv's Avatar
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    simply amazing.....

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    Super Moderator Hofmannhp's Avatar
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    Registry

    Quote Originally Posted by Steve Schell View Post
    ..... This Iconic is the oldest one I have seen, and uses the early style dividing network (serial #70) as pictured in the Lansing Iconic bulletin of 1937:
    .....
    Hi Steve,

    amazing stuff.....I would like it to write this years into the columns of the registry sheets
    Is it possible to put it into the registry ?
    pls give me a PM for this....

    HP
    Please help us save more info about the vintage systems. Let us register your speakers and drivers.

  5. #5
    Senior Member Steve Schell's Avatar
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    I forgot to mention that the buzz had likely resulted from a thick deposit of oxide from the plating on the center pole. A "skirt" was visible where the voice coil had been, and the deposit was much thicker below that point. It was wiped off before the picture was taken. Ever seen the yellowish mung on old Altec mounting hardware? Similar stuff.

    Scott, I discuss the sound of the 801s a bit in the other thread. Basically they sound to me like 802C or D but punchier, with super sharp and clean transients, and very sweet on top with no breakup tizzy sound at all.

    Here's a scan of a quick 1/3 octave RTA measurement at the mouth of one of the h.f. horn cells. The low frequencies were from the woofer section which I had not disconnected. A multicellular disperses highs widely in a similar way to a conical horn, so the curve gives evidence to the driver's naturally downsloping power response; no on-center beaming like an 811 to make it look flat to 10kHz. The level falls about 10dB from 1kHz. to 10kHz. Considering that, it is a very smooth performer up to 10kHz., above which it falls off pretty rapidly. The top octave will probably measure flatter on an 802 with its tangential compliance, but they sound a little more "tsss, tsss" to me.

    Overall, I am really knocked out by the majestic sound of these 70 year old speakers.
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    RIP 2010 scott fitlin's Avatar
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    Like I said, your amazing! And I love finding out about the really old stuff, and how good it really did sound.

    Quality materials, and top notch American made craftmanship in all its glory, drivers produced that excelled beyond their time!

    Thank you for sharing.
    scottyj

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    Blackburn's radial-slit phase plug patent, filed 1937, issued 1939;

    http://www.google.com/patents?id=LfZ...s_maxy_is=2007

    Note lack of assignee...meaning Blackburn personally owned the patent rights...

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    Senior Member spkrman57's Avatar
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    Thanks Steve!

    I always look forward to your posts on the very vintage type audio gear of yesterday!

    Ron
    JBL Pro for home use!

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    I found it particularly interesting that Blackburn's patent illustration shows a threaded horn connection as opposed to stud & plate...

  10. #10
    Senior Member Steve Schell's Avatar
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    Moldyoldy, thanks for linking to Dr. Blackburn's patent; I should have done this.

    I have often wondered who originated the idea of the radial slit phasing plug. RCA collaborated with the MGM team during the creation of the Shearer Horn System. Lansing Mfg. Co. supplied many drivers to RCA in the mid to late 1930s, as well as to the Loews theatre owners for their new systems that were otherwise all RCA. RCA was building their MI-1428A compression driver by late 1936; it had an eight slit radial plug, and was soon replaced by the MI-1428B with its fifteen slit plug. These were very different drivers than the Wente-inspired Lansing drivers, as they used a 4.5" composite cone diaphragm and exited out the end rather than through the body of the driver. RCA had been in a pitched battle with Western Electric over what it felt was its domination of the theatre business, and evidently took pains to avoid building any design that could be considered an infringement of W.E.'s patents.

    Lansing began building Blackburn's radial slit plug in 1936 or 1937 when the threat of legal action dictated the change. It was said in print at the time that the reason for the change was that the radial plug was easier to manufacture, though we know the real story. Isn't it curious though that Lansing reverted to the circumferential plug in both driver formats as soon as conditions permitted?

    By about the time Dr. Blackburn's patent was granted, he had left Lansing to work on radar for the government at M.I.T. Lansing had likely reverted to the circumferential plug by then anyway, so there was no need for assignment of the patent to Lansing Mfg. Co.

    Max Graham of RCA is generally credited with the design of the RCA 1400 series drivers. He worked under John Volkmann, who (as John Hilliard mentioned in an article) travelled to Hollywood to assist the Shearer team. Dr. Blackburn was of course a member of the team, who then later went to work for Lansing. Somewhere in this critical mass of brilliant minds someone originated the concept of the radial slit phasing plug. Was it Blackburn, Graham or Volkmann? They are all gone now, so we may never know for sure.

    The RCA 1400 series compression drivers used a 2.5" 16 TPI attachment to the horn and a 1.5" exit, as did the Lansing 284, 285 and 284B drivers. The business between Lansing and RCA ended around 1940, and each adopted new mounting standards shortly after. The Lansing 287 driver, introduced in (probably) 1940 used a three stud mounting that was retained in the 288. RCA shifted to a two stud mounting about 1942.

    Below are a couple of pictures of the RCA MI-1428B phasing plug, a Lansing large format driver with circumferential phasing plug (may be a later 287) and a Lansing 285 with the Blackburn plug.
    Attached Images Attached Images     

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    Beautiful, museum stuff, Steve, Thanks! I'd never seen the RCA innards before. Is it an illusion, or are the RCA exit openings slightly 'twisted' about the axis?

    Thanks for the clarification of the ambiguities relating to Blackburn's patent, too. I had assumed the assignee was designated when a patent was filed, rather than later, when it was issued.

    There are likely many details of "who did what, when, and why" we'll never know for sure. I've been on a patent binge recently, with the discovery of Google's patent search abilities. What started as simple curiousity, soon led to the realization that neither Lansing Mfg., nor Altec claimed any patents until fairly late in the game, while Bell, WE, RCA, and others made regular offerings. Can you shed some light on this please?

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    Senior Member glen's Avatar
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    A fascinating discovery Steve!
    Thanks for sharing it with us.

    I think you should be named the official PaleoAudiologist of Lansing Heritage!
    glen

    "Make it sound like dinosaurs eating cars"
    - Nick Lowe, while producing Elvis Costello

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    Thanks Steve for showing this to us .

    It's great to see those pictures of such a monumental find .



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    moldyoldy,

    Thanks for the link to that Googled "Blackburn" patent , very interesting.

    - FWIW / I also notice the lack of Hilliards' name anywhere on that document ( notwithstanding everything else )


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    Quote Originally Posted by Earl K View Post
    moldyoldy,

    Thanks for the link to that Googled "Blackburn" patent , very interesting.

    - FWIW / I also notice the lack of Hilliards' name anywhere on that document ( notwithstanding everything else )

    Most welcome, Earl.

    Noticed that too, didja?

    Until Google opened the text on those old patents for us, it was almost as easy to invent something as to find it in 'prior art'. I've found various "duplexes" by others as far back as '29. Altec had no patents until Carrington's Duplex, filed in '47;

    http://www.google.com/patents?vid=USPAT2568883

    and Lansing Mfg. had none. None of either company's early "claim to fame", legacy products including VOTT were patented, unless earlier, and by others.

    W.E.'s divestiture gave Altec free use of their prior art. Apparrently none of Altec or Lansing's products differed enough from that prior art to warrant their own patents until much later.

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