Superior Electric gave the name Luxtrol to their line of theatre dimmers for use in their own package (portable) switchboards, but they were also the principal supplier of dimmers to other manufacturers for use in permanent installations. For the Luxtrol story, click here.
For thirty years starting about 1955, autotransformers became the most prevalent dimmer sold, replacing resistance plates which had been in use since 1892. Below, a Hub Electric resistance board at Hendrix College in 1950, with magazine (fuse) panels shown to the right.
Resistance plates had several drawbacks, among them minimum ratings necessitating supplemental ghost, dummy, or phantom loads usually located in the stage trap room and cabled from the underside of a floor pocket.
A Westinghouse resistance switchboard, photgraphed in 1931, at Taft School's Bingham Auditorium. Enclosed knife switches (1) controlled each dimmer (2), and pilot switches (3) operated remote contacters which in turn energized a given dimmer bank, or color. When rotated clockwise, dimmers interlocked with master handles which were not dimmers (4 and 8), and the masters could lock into the grand master (7) whose handle could be extended for better leverage. The board master switch (5) controlled all bank contacters and was paralleled to an extended control switch at the back of the house. A lock switch (6) overrode the remote switch, so amateur critics could not arbitrarily black out the stage.
A 1925 Hub advertisement stressed that their board installed at the 46th Street National Variety Artists clubhouse made "the switchboard operator as much a part of the act as the artist himself."
That ceased to be the case in the 1980s when electronic dimmers were banished from the wings and relegated to a box in the back.
This suggested school stage plan was part of the Major-Frank Adam catalog of 1922.
The markings on the dimmer handles and switches keyed to the color of the stage lights controlled, as on the Hub board at the Atlanta Fox.
The primary source of lighting was borderlights in three or four color circuits, as permanent as the switchboard. (Photo courtesy Historic Stage Services.)
Front lighting emanated from the footlights, the still extant double-row Kliegl set at Radio City Music Hall shown here. Motorized to disappear, the Music Hall foots (and cyc) are circuited in five colors, amber, green, red and double blue.
Where most borderlights ended up:
A specification for each switchboard was prepared, such as this example for the Taft School installation, whose consulting engineer Clyde R. Place was also responsible for Radio City.
As illustrated in the 1954 GE catalog, the McCandless system was beginning to seep down to high schools, with lekos for front lights, fresnels for the stage electrics, and stage booms complete with beam projectors.
Circuit beakers (1) served as switches for autotransformer dimmers (2), and on Gary Mustante's General Electric board, the grand master acts as both interlocking master and proportional master, if desired, but autotransfomers had a maximum capacity of only 8000 watts.
Gary's board can be pegged as a General Electric because of its distinctive patch plugs, as shown below.
Each patch panel was unique to its manufacturer, such as Kliegl:
The signature Kliegl patch:
Although early Century boards were fitted with Ward-Leonard autotransformers, they later went Luxtrol.
A Century patch panel:
An Ariel Davis board with Davis slider autotransformers and Luxtrol proportional masters:
An off-brand board with Luxtrols made by Kelek, perhaps a one-shot.
Another off-brand, Federal.
The wonderfully luminated Hub patch panel:
And courtesy Rick Zimmerman, the worst switchboard of all time. Built by Hub and equipped with Superior Variac-type autotransformers, it was designed by James Hull Miller and passed off to unsuspecting pigeons as the real thing.
Many photographs herein pulled from Control Board site where everyone is anonymous. Atlanta Fox dimmer shot courtesy Tim Bjorklund.