Distributed Dimming

[MarshallPope]

A method in which dimmers are located near the fixture(s) to be dimmed, rather than being placed in a centralized dimmer rack. This can allow for cheaper installation costs because of the reduced need for permanent wiring, as well as making it easier to hide cables for certain events where appearance is important.

In the 1980s, Morpheus Lights of San Jose, CA was perhaps the largest proponents of power distribution in the truss. (They also pioneered traveling moving lights inside the truss: FlipBox, the antecedent of today's SwingWing.) Several attempts have been made to put dimmers in the truss (McManus, See Factor, HiLights, etc.) but all have failed.

Note that dimmers/distros in the air is not a new concept:

...Many of us have seen the Rack vs. "dimmer at the fixture" debate before. In the 1980s some Rock&Roll lighting companies tried to convince us "dimmers in the truss" was the future. I don't know of a single touring company doing that today. Of course, I had the same thoughts about powered speakers.

EDIT: Research shows that the concept of "dimmer at the fixture" was proposed in A Digital Lighting System for the Theatre, Master Thesis of Fine Arts Yale School of Drama pp. 1-48, May 1974 by Dirk Epperson. Once an assistant to LD F. Mitchell Dana, Mr. Epperson today is VP and Co-Founder of TIBCO | Telecommunications, a software solutions company.

From High rollers: The roster of Las Vegas players :

The control system in Callahan's crystal ball had the dimmer at the fixture by 1988. While a few touring companies kludged together SCR dimmers in truss-mounted applications, the real possibilities and pitfalls for dimmer at the lamp did not become clear until the commercial application of chokeless transistorized dimmers to distributed dimming systems in about 1991. And despite the fact that distributed dimmers have become reliable, the market has been slow to adopt them en masse. Perhaps we will have to wait for the arrival of two new advances to finally and fairly evaluate distributed dimming: dimmer in the fixture, to completely avoid a separate dimming device, and the advent of cheap, reliable wireless data transmission technology, to get rid of all those pesky data cables! Both these advances should be just around the corner.

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...I have also seen broadway style shows put a sensor 24pack riding on top of the FOH truss.

If one happens to put a half-coupler through each of the bottom holes of an SP6 or SP12 pack, one may find that the couplers are perfectly aligned to fit 20.5" truss. I wonder if they planned it that way?

See also this thread: http://www.controlbooth.com/forums/l...t-raceway.html , disregarding the debate regarding IGBT vs. SCR dimming.