Theatre Design & Technology - Spring 2008 - 21

One of the most often used switching schemes was a "two
scene preset" concept that was marketed by the Hub Electric
Company of Chicago. Each dimmer circuit was provided with
two double-throw pilot switches, one switch corresponding to
each of two lighting scenes ("A" and "B"). Each switch controlled a separate operating coil on the remote contactor for
that circuit. (Fig. 3)
In each scene, throwing a pilot switch up connected that
contactor coil to a "hot" control bus, and the contactor would
then energize that lighting circuit. Throwing a pilot switch
down, however, would connect it to a similar pair of color
master switches at the end of that color row. These could then
either be thrown up to the "hot" bus or down to connect them
to a single pair of grand master switches.

switch (which then connected either to the "hot" bus or to a
grand master switch), or to a group of on-off "scene" switches.
Most commonly, there were five such scene switches for
each dimmer circuit, forming a "five scene preset" arrangement. For more elaborate installations, there sometimes were
ten switches (ten scene preset). All of the individual switches
for each "scene" were controlled by a master scene switch at
the center of the board. Thus, there would be either five or ten
master scene switches. Each dimmer circuit could be switched
into any one of the five or ten scene presets, and these could be
used over and over again through the running of a show simply
by throwing the appropriate master switch as desired.
The Trumbull Electric Manufacturing Company of Plainville,
Connecticut made manual dimmer boards using the brand

The disadvantage of proportional mastering, however, is that the dimmer capacity
of the board must effectively be doubled; that is, in order to master six 1000-watt
dimmers, a 6000-watt master must be installed.
Therefore, the on-off control of individual dimmer circuits could be mastered by that color row, or by the grand master switches, and many dimmers could be rapidly switched on
or off with the flick of just one (or just a few) switches.
Proctor's Theatre in Schenectady, NY once had such a
"Hub" board (complete with slow-motion wheel) and the author was once told by a long-time stage hand there that they
used to "initiate" new stage hands by sending them to the contactor room just as such a scene change was about to be run
on the board. The simultaneous operation of dozens of sparking and clattering contactors would usually send the initiate
screaming from the room !
It is generally recognized that the largest such Hub board
ever installed was at the former Roxy Theatre, located at Seventh Avenue and Fiftieth Street in Manhattan, New York City
(Theatre 1979). This six thousand seat "movie palace" opened
in 1927 and was demolished to make way for an office building in 1960. The Hub board at the Roxy was located in its own
room, off downstage right. It was twenty-two feet in length and
contained over five hundred dimmers! (Figs. 4 and 5)
An earlier such control scheme, called "pre-selective"
switching, was developed by the Major Equipment Company of
Chicago and marketed by the Frank Adam Electric Company of
St. Louis. This also used two double-throw switches for each
dimmer circuit, but one switch controlled the closing of the
circuit contactor while the other switch controlled its opening.
Thus, it was really more of a "one scene preset" type of control,
and it never became really popular.
Later on, then, the Frank Adam Company developed a
multi-scene preset switching scheme that was used extensively.
A three-position switch was used for each dimmer circuit, and
the contactors had just a single operating coil (thus, they were
cheaper). The three-position switch connected the contactor
coil to the "hot" control bus, to a double-throw color master

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name of "Controlite." By the 1930s, Trumbull had been taken
over by the General Electric Company, but continued to manufacture boards under their name. The 1936 board mentioned
above, that was saved in the 1990s, is a Trumbull "Controlite"
board with General Electric on the nameplate.
Trumbull sometimes used a preset switching arrangement
that had been developed by a man named George Hyser (Brenneman 2006). This was actually a multi-scene preset (usually
five scenes) as well, but all of the individual scene selector
switches for the dimmer circuits were grouped together on a
common panel module at the center of the board, along with
the scene master switches.

road Boards
Throughout most of the twentieth century, the development
of "Broadway" shows involved a lengthy series of out-of-town
performances in major eastern cities other than New York City.
If successful, the show would then be booked into a Broadway
theatre, hopefully for a long run.
While "on the road," the show would carry along all of its
own lighting equipment which included dimmer boards. Thus,
a very rugged type of portable board evolved which came to be
know as a "piano board." (Fig. 6) This name resulted from the
fact that the crate into which it was built very closely resembled
a shipping crate used for an upright piano.
Piano boards consisted of twelve or fourteen resistancetype dimmers equipped with mechanical mastering and a row
of stage pockets for circuit connections. The dimmers usually
were rated for either 3000 or 5000 watts load each. This was
important because resistance dimmers had to be loaded at, or
close to, their ratings in order to function properly. If used to
control a load significantly less than its rating, such a dimmer
could not dim the lamps it controlled all the way to black-out.

2008

Table of Contents for the Digital Edition of Theatre Design & Technology - Spring 2008