Theatre woofers

[Thom]

Where are all the ampex/jbl theatre woofers? I have one. I used to have two The theatre mine came out of had eight. They have salvaged thousands of theatres over the years, and I've never seen another one in my life, which to many peoples dismay, has been several years. I thought mine was made at the dawn of time, but I've learned that's not the case because it has a cast and machined magnet pot. I've poured through the internet looking for someone who might be in the theatre salvage business. These were originaly used infinet baffel but my god you, enough! I'd just like to know if anybody has any information. Sure whish I'd bought eight, but couldn't afford it when they were tearing the Alhambra down. This was a real upscale movie house, but it couldn't have been the only one, and it seems like no one wants to listen to a straight sided stiff suspinsion speaker like that today, so they should be somewhere.

[Steve Schell]

All or most of the blue label "Jim Lansing by Ampex" woofers I have seen have been the 150-4 32 ohm model. I have seen several dozen of them over the years, either on ebay or in the hands of dealers and collectors. These woofers have been a cherished collectible among overseas audiophiles for at least 30 years, probably due to their similarity to the 150-4C 16 ohm woofer used in the early Paragons and Hartsfields. My guess is that most of the surviving ones have been exported, as the vintage audio dealers have always been able to get good money for them.

[Don McRitchie]

There never were that many JBL theater systems to begin with prior to the 1980's. Altec Lansing was by far the dominant supplier to the cinema industry, starting in the 1940s and lasting through the 1970s. In 1953, the Altec Voice of the Theatre was certified as a loudspeaker standard by the Academy of Motion Picture Arts and Sciences. This certification gave Altec a standing in the industry that was impossible to dislodge. It was only when the industry adopted a new standard (THX) that a window of opportunity opened up. The THX standard was developed using JBL speakers and it allowed JBL to turn the tables on Altec to pretty much shut them out of the industry.

Prior to THX, JBL mainly limited their forays into the theatre market as a partner in joint ventures. They were too small and saw too many risks in attempting to dislodge Altec on their own. In hindsight, it was a wise move because the first three JBL theatre initiatives were ultimately all failures. Had JBL been forced to assume the risks of these failures on their own, it could have very well sunk the company.

The three major initiatives were the Westrex collaboration in 1953, the Ampex TODD AO project of the same year, and the Ampex Cinetron project of 1965. The Westrex project was limited to foreign markets and had some initial success. However, by the end of the 50s that collaboration had ended with Westrex never becoming a major cinema supplier. The TODD AO project was intended to be competition to the then new Cinerama widescreen projection and multichannel sound system. However, the TODD AO system was always in the shadow of Cinerama, and by the end of the 50s, the sound system portion of that project had ended as well. I believe that I read somewhere that less than 100 theatres installed the TODD AO sound system.

The Cinetron system was Ampex's second attempt to break into the cinema market with their own sound system using JBL speakers. A whole family of speakers was developed for large mains, small mains, and fill speakers. According to the developer, exactly one system was installed before the project was canceled.

[spkrman57]

Thanks Don for the background on the cinema scene.

I knew Altec had a good standing in the theater community, but I thought JBL was with them to a lesser degree.

I guess with looking at JBL being a cinema giant now that it seems less possible that Altec was leader in field in such great numbers.

Regards, Ron

[Thom]

I can't believe this was a one off system. Take a D130 frame. Put a ring on the front of it, mabe 3/8 of an inch thick to make it deeper. Stick a magnet assembly from a 375, complete with a machined face and 4 drilled and tapped holes, hand make a cone, you can see the overlap. Use a smaller hand made cone for a dust cap and then hand glue three paper rings around the outside at various heights for stiffening and thats it. What would have been the throat if it had become a driver was stuffed with glass. I thought that maybe this was one of there very first jobs, but the magnet structure is cast and machined so that meens at least mid 50's. It weighs maybe 32 lbs. Have you seen that? The top end for the system was 375 (more than one) with that venetion blind looking lens thats maybe 4 or 5 feet wide. This didn't say "Jim lansing" this is painted black wrinkle and just says ampex, But I know that frame and I Know that magnet.
I haven't spent my life looking for it or anything but I've sort of kept an eye out, for more than twenty five years.

[Mr. Widget]

This didn't say "Jim lansing" this is painted black wrinkle and just says ampex...

Do you have a camera? A photo would probably help the hardcore vintage sleuths figure it out. Since it came out of a theater, I doubt it was a one-off prototype...


Widget

[Steve Schell]

Thom, I'll second Widget's suggestion that you post some photos of this driver- it sounds fascinating. The added ring on the front to allow a deeper straight sided cone is normal for the 15-4 type drivers, but the 375 motor is not. With the handmade cone it does sound like a prototype or someone's hand made construction. There are quite a few oddball one-off drivers out there, many of them prototypes, and if they worked they were often put to work in some application. It is always fun to study them.

A friend of mine has been developing a new line of drivers in both permanent magnet and field coil versions. Just as you described, he has been mating JBL large format compression driver pots to JBL baskets for his prototypes. A 375 motor has a bigger alnico magnet than any of the JBL woofer motors, and there is also room in that big pot for a larger field coil.

There are several instances where Jim Lansing used the same dimensions on different products. The Lansing and Altec Lansing large format compression drivers, JBL D-130 and 131 all used the same six fastener locations and hardware size to secure pot, top plate and basket (cone drivers). A 288 pot will bolt right on to a D-130 basket.

Another friend has what may be a one off prototype 15" coaxial driver. It is labeled "Vondee, Los Angeles" and "VD-1A." It has a beautifully cast basket and pot structure. It uses a field coil motor for the woofer; the coil is dated 1944. It seems to be inspired by the Altec 601 15" field coil Duplex of 1943, as the basket is very similar to the field coil Lansing baskets though a bit fancier. It was fitted with a Lansing cone kit with 2" voice coil and phenolic spider. A hole is bored through the woofer center pole to provide a path for the high frequencies. At the rear the hole is enlarged and threaded to accept a screw on driver. When my friend acquired it a later vintage Atlas compression driver was installed and the combination was in a utility cabinet. I'd post pictures but my regular computer is out for repairs.

I've searched ebay and the web but have yet to find out anything about Mr. Vondee. Perhaps he was an understudy or competitor to Jim Lansing, but who could tell us about it now?

[Thom]

It's at my mothers in Sacromento. I live in San Jose. Anyone from this area knows thats pretty close so I'll grab it next chance I get which should be pretty quick and take some digital photos of it. It had to be a factory job because of the two that I had one had been machined to fit a horn an one had not but they were the same. I figured they had run out of the pots that had set aside for woofers so they just grabbed one that had allready been machined. I think the one I still have left is the machined one. I really don't know when the sound system went into the Alhambra, but I always thought the speakers were from before JBL the company, like sometime in the 40's but from reading here they had to be at least 54 or 55. The first thing that hit me when I looked at it was the Magnet and then the dust cap. I had always pictured James Lansing making it but not so I guess.

[Don McRitchie]

Thom

Are you sure that the woofers you have are not what is illustrated below? This is the JBL 150-4. As result of the Ampex TODD AO collaboration of 1953, Ampex secured the rights to manufacture JBL drivers and enclosures in their own facilities. The 150-4 was one of these drivers and it was the most frequently used bass driver in their theatre systems.

To Steve, I've never been able to get definitive measurements, but I believe that the 375 motor did not use the largest magnet of all JBL drivers. From cutaway illustrations, it looks like the LE15 magnet was larger. That magnet is a solid slug of 4" nominal diameter Alnico. Ed May needed to specify a huge magnet for his design of the LE15 because of the underhung motor topology combined with a relatively high x-max for the times. To get any kind of reasonable sensitivity, he needed a huge total flux since much of it would be lost to the motor for the portions of the deep gap that were not filled with wire from the shorter coil.

[Bob Womack]

The six-track TODD-AO system was selected as the audio system for the VistaVision system of 1957. This involved horizontally sprocketed, wide-screen projection with surround sound. Essentially, they turned 35mm film on its side and fed it horizontally through the camera and shot on twice the frame width. Only two theaters were ever built in VistaVision and only one film was released. Those theaters still exit and are still maintained with their TODD-AO surround arrays. The film has gone on to become the longest continually-shown film in movie history and the film shown to the highest aggregate audience in history.

First the technical details. TODD-AO sound consists of five speakers arrayed behind the screen and one channel of surround, distributed to speakers in the ceiling. The theater is designed with the rows of seats lying in anechoic "tubs", consisting of an absorptive wall fore and aft, that are built high enough to isolate each row both acoustically and visually from the others. We could use that in the age of cel phones. The acoustic result is proper radiation from the front array and a very intimate surround coming from above.

In 2001, the film underwent a refurbishment at Cinesite, the now-defunct Kodak film restoration organization. The soundtrack was returned to TODD-AO to be remixed. Interestingly, the TOOD-AO folks had to do a little research to recall the details of their own, long dead sound format. What is this film and where are these theaters? The film is The Patriot, an introductory drama directed by George Seaton (Miracle on 34th Street) and starring a very young Jack Lord (Hawaii 5-0) shown continually throughout the day at Colonial Williamsburg, VA's two original theaters. The cast is a virtual "whos-who" of character actors from the period, which is amazing because the whole lot of them had to be picked up and transported to the Williamsburg Colonial District, where the film was shot. The restoration of the film was an amazing feat, given that the works prints, masters prints, and separations had all decayed after forty years. As an example of the lengths to which they had to go, they were able to salvage color-correction of some of the scenes because the buildings used in the film still existed and because the costumes from the film had been conserved by Williamsburg's museum currators the same way as the actual 1700s period artifact clothing in the collection and were available for color comparison.

I have a little hisory with the film: The film premiered on March 31, 1957, a month before I was born. On my first visit to Virginia and Williamsburg in 1962, I first saw it. Right about the time the restored film was premiered, I discovered the history and restoration of the film. After I tracked down the man in charge of the restoration, I was fortunate to meet the crew responsible for the restoration and to be given a half-day tour through the complex as a professional courtesy. If you are in the area, knowing the history of the film adds a little bit to your enjoyment of a trip to Williamsburg, the colonial capital of the colonies. Here's more:

http://www.history.org/Foundation/jo...04/patriot.cfm

http://www.history.org/foundation/ge...t_restored.cfm

Bob

Addendum: The Patriot theaters and the film were converted to standard 70mm in the late 1960s. The VistaVision projectors were sold to ILM and have been used since in special effects operations. The six-track TODD-AO soundtrack is now played off DVD in English with simul-cast of up to six languages available via Acousti-wand headsets.

[speakerdave]

Jeez, I love this forum. We got class!

It is so cool to start looking at threads of a Saturday morning and come upon a gem like this. Thank you very much.

David

[Thom]

I'll get pictures as soon as I can. There were eight woofers behind the screen and the magnet assy looked like a 375 and at least on of the magnet pots had actually had the face (on the woofer it was the back) machined flat and four mounting holes (as in horn mounting) drilled and tapped. the outside of the cone was (is) three paper rings running around it at three different distances from the speaker edge the rings are on edge and obviously hand glued, parts of this speaker are so hand made that I was sure it was made before the start of JBL as a company. I now now that the D130 (without the "O" ring groove on the back) casting and even more the cast and machined magnet pot means 55 at the earliest. Again will get pictures at earliest chance. I'm not sure but I think the Alhambra was one of the earliest 70 mm theatres I'm not real expert at such things so if that last statement shows me to know nothing of early cinema didn't say I did. The add on to the frame is probably the same.

[Thom]

As to magnet sizes that is where JBL did a little of a P T Barnum bit. Altec was advertising magnet weights LBL advertised "magnet assy weight. D130 11lbs, 375 27lbs, many years later LE15A 19 lbs. When I get pictures you'll recognise the 375 pot. I think it was the only other pot they had for a 4" voice coil. Every thing I've red suggests same magnet structure D130 and 150-4. I have no Idea what is under the pot or the reason for it or yhe hand made cone or the reason for using an inverted cone for a dust cover.

[Thom]

Dug out this woofer have pictures of it next to an LE 15A And a D130. Gave up trying to post them tonight will try again tomorow. The surround which is paper is starting to rot which is kind of a hartbreaker. If you rest it on the floor on it's magnet and do the same with an LE15A the LE 15 will slide underneath it. I used to have a pair in a C55 cabinet and it sounded like nothing I ever heard. From all I've read it couldn't have hit the lowest octive but you couldn't tell me that then. A Virgil Fox Record could clear the neghborhood. The Alhambra theatre was builyt in 1927 so the sound systym could not have been originol. It was the fanciest movie house I ever saw. It had lodge seating in the rear were gorgeos sofas and not. The city of Sacramento renamed 31st street to Alhambra after the theatre. I new the guy whosalvaged the sound system. He sad it didn't say JBL or JIM Lansing or anything else except Ampex. When I figure out how to get the pictures up you'll see the magnet pot looks like the front of a 375 including a machined surface 4 holes and a 2 inch hole. The top plate is several times thicker than a D130 but not quite as thick as a Le15/K145 but the magnet dwarfs the LE15
I know they made 8. I never had any reason to believe they were real rare till one day I put it together that nobody I have ever spoken with has ever seen one. It has the stiffist cone (not suspension) that I have efer seen and then it has those stiffining rings glued to it.

[Thom]

Give me a break. The website says the max dementions for a file are 1024 x 0
they were large files at first and I compressed them but not that far. Is that one of the features that we got the new system for?