Vintage Lighting A bit of research on the development of Reactance Dimming in the US

Scenemaster60

Well-Known Member
In response to Steve Terry's post a little over a week ago regarding a discussion of the history of lighting control, I thought I would share some of the research that I have done over the last few months on the development of remote control dimming in the US between 1920 and 1950. The bulk of this research has really been hunting down the source materials that Joel Rubin used for his 1959 doctoral dissertation THE TECHNICAL DEVELOPMENT OF STAGE LIGHTING APPARATUS IN THE UNITED STATES, 1900-1950. His bibliography is AMAZING and I have had great fun tracking down some of this material!

I have never met Joel personally or had any correspondence with him regarding this material. His dissertation is the only place that I have ever seen the history of remote control lighting using saturateable-core reactors outlined in any detail. Since Joel would have been doing this research before the days of photocopiers, I would presume that all of the source materials would have been referenced personally and compiled in the form of hand-written notes. This means that there was no easy way to include photos or complicated diagrams.

I will start by posting appendix B from the dissertation which gives a list of those venues where remote controlled reactance dimming was installed in the period from 1920-1950.
 

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  • Pages from The technical development of stage lighting apparatus in the United States, 1900-1950.pdf
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It is no surprise that when the electrical magnate Samuel Insull build the Civic Opera House in Chicago in the late 1920s that he would have wanted the most sophisticated and technologically up-to-date lighting control system. To this end General Electric created a remote-contolled reactance dimming system that was one of earliest 2-scene preset systems. It employed 141 dimming circuits and had multiple arrangements for mastering and submastering. Here is an article taken from a publication called Better Theatres from 1929, the year that the Civic Opera House opened.

I don't how long the system was in use. I do know that Kliegl installed a new SCR dimming system in the hall in 1974. I am uncertain if this system was a direct replacement for the reactance system or if there had been an intermediate system (or systems).
 

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  • 1929 Civic Opera Chicago.pdf
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Not to be outdone, in 1932 the Metropolitan Opera in New York announced that they would be installing a remote-controlled reactance dimming system. I was also manufactured by General Electric and its switchboard contained controls for 3 scene presetting. Here is an article about that system as well a copy of the patent that GE filed in association with this installation.

This system was in use from its installation until the building was torn down in the mid-1960s when the company moved to their new home in Lincoln Center. The new system in Lincoln Center was a Ward Leonard Solitrol system.
 

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  • Met Opera 1936.pdf
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  • Met opera induction patent 1932.pdf
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Certainly the most famous of the remote-controlled reactance dimming systems was that which was installed in the main auditorium in Radio City Music Hall. One of the most remarkable things about this system was that it was in continuous use until 1999! Its controls allowed for 5 scene presets. It's pretty amazing the things that were done with this control system over the years!

Here is an article from 1999 that outlines some of the history. I have also included the patent that was filed in association with it.

This system was replaced by ETC in 1999.
 

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  • Pages from Radio City 1999.pdf
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  • Radio city induction patent.pdf
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Certainly the most famous of the remote-controlled reactance dimming systems was that which was installed in the main auditorium in Radio City Music Hall. One of the most remarkable things about this system was that it was in continuous use until 1999! Its controls allowed for 5 scene presets. It's pretty amazing the things that were done with this control system over the years!

Here is an article from 1999 that outlines some of the history. I have also included the patent that was filed in association with it.

This system was replaced by ETC in 1999.


Wow, 1999! How angry was the Union that the ETC Unit was "takin their jerbs" ;-)
 
I don't think it was that big of a deal by that time. That battle had been fought in the 1970s over on Broadway. I thought I have read somewhere that the folks who had been keeping the reactance system operational towards the end were a bit relieved when it was taken out of service. Many of the repairs required the hand fabrication of replacement parts.
 
Great series of posts. I was intrigued by the band car and elevators. I wonder if any of the musicians had to take motion sickness pills. The idea that the band car can rise to stage level, move back to the upstage elevator, then sink to the basement, only to reappear in the original position is amazing. There is also the story that during WWII, there were military troops stationed back stage, the mechanical systems for the lifts was the same as used on battleships and they didn't want any spies to find out how they worked. I am sure the soldiers got ribbed a lot for having that job, having to hang out with the Rockettes.
EDIT: the engineering for a turntable that spans 3 lifts must be amazing.
 
One more tidbit for today. Here is an excellent article that goes into the nitty-gritty of how reactance dimming worked on an electrical level. It is called "Electron Tube Control for Theater Lighting" and is from the Journal of the Society of Motion Picture Engineers, March, 1935.
There is also a great picture of the control board that was installed in the Center Theatre in NY. Unlike the three installations that I showed above that used compact pilot boards where the operator had full view of the stage, the Center Theatre installation used a more traditional looking (for the time) switchboard that was located backstage.
 

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  • Center Theatre NY 1935.pdf
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Never seen one of those first hand. Do have an old variable power supply from the 50s that works on the same idea. (Sat core, DC supply using a selenium rectifier, and a wire-wound resistor that sets the field DC.) As with everything else in the world's history, it's back in my barn somewhere.
Thyratron tubes I do have. Seeburg Jukeboxes from the 50's and early 60's used the 2050a tube to fire the record lock mech and to drive the stepper unit (used with wallboxes, think diner.) Nice flashy/blinky tube to watch when it fires! The control banks for these dimmers must have put on quite a light show by themselves!
 
Ahhh, flashy/blinky tube made me think of old radios with the cats eye tube for a tuning meter.
 
Ahhh, flashy/blinky tube made me think of old radios with the cats eye tube for a tuning meter.
@Scenemaster60 @JohnD and @JD
I knew of three Strand saturable core dimming installations in the 1960's and 70's.
I operated one controlling an evening sound and light show in Hamilton, Ontario's Dundurn Castle during the mid 1960's. Hamilton's CHCH TV had a similiar saturable core dimming system in their King Street West tertiary studio space during the same time period.

When I migrated to Stratford, Ontario's Stratford Shakespearean Festival in the spring of 1977, the festival still had a 3 scene Strand saturable core installation in regular repertory operation in their Avon proscenium venue in the heart of downtown Stratford until approximately 1978 or 79.

Saturable core; Solid state in the sense that you wouldn't want to drop one of those HEAVY lumps of laminated (but almost solid) steel on your toes.
When Stratford replaced their saturable core system, I recall donating two or three of the cores to CHCH TV in return for the use of their Garner open reel tape eraser to bulk erase a few 14" reels of 2" multi-track audio tape. My 1970 Chevrolet station wagon was 'relieved' to have the saturable core dimmers removed from atop its rear axle.

Saturable core dimmers, definitely solid, indestructible and reliable; no carbon brushes to replace.
Thanks for the trip down memory lane.
Toodleoo!
Ron Hebbard
 
@Scenemaster60 - wow! Great stuff you were able to find. I never met Joel Rubin, either, but vaguely recall his name from my reading back in high school (Theater Crafts? may have mentioned him a couple of times). The church my family attended in SoCal had remote GE reactance architectural dimming... installed around 1950, IIRC.
 
Scenemaster - You say saturable core and I say magnetic amplifier. Same thing, correct? My college had mag amps - Metropolitan Stage Lighting was the name of manufacturer IIRC. Basic two scene preset. The mag amps always had a slight lag or delay. I can recall the TD telling board ops to "anticipate" an actors entry - like we needed x-ray vision to see them behind the leg starting to enter. Never had that problem with thyratron tube dimmers. Other problems - yes - but not lag.

I had dinner with Dr. Rubin and Bill Warfel back in mid 1980s - and I think we chatted at a conference once or twice since. Yale mafia, you know.
 
Scenemaster - You say saturable core and I say magnetic amplifier. Same thing, correct? My college had mag amps - Metropolitan Stage Lighting was the name of manufacturer IIRC. Basic two scene preset. The mag amps always had a slight lag or delay. I can recall the TD telling board ops to "anticipate" an actors entry - like we needed x-ray vision to see them behind the leg starting to enter. Never had that problem with thyratron tube dimmers. Other problems - yes - but not lag.

I had dinner with Dr. Rubin and Bill Warfel back in mid 1980s - and I think we chatted at a conference once or twice since. Yale mafia, you know.
Bill you are correct about them being essentially the same thing. It would appear that the shift of names in the industry largely happened after WWII. From my observations, it seems that systems called "magnetic amplifiers" from the 1950s had more solid state components in the control circuitry than earlier systems.
 
There is a pretty good discussion of saturable core reactor and magnetic amplifier dimmers in the 2nd edition of Bellman's "Lighting the Stage: Art and Practice" pages 191-195. His take was essentially the mag amp was a highly sophisticated saturable reactor.
 

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