Theatre Design & Technology - Spring 2009 - 7

letters to
the

editor

There are many interesting ideas in the Jeffrey Gress article "The demise of Patch Panels" in the Winter 2009 issue of Td&T.
I can understand the frustration Prof. Gress must have on projects with budget limitations but that's where I start to argue because,
in practice, all projects have budgets and therefore limits. Also, I can understand his frustration with the design process which when
successful will weld many disciplines into a unified performance space-but can also fail to achieve that unity. However, I've read this
article twice, thoroughly, and I can't agree that he is successful in arguing his central theme, the demise of the patch panel as the root
cause for inadequate lighting positions in modern theatre design. "Inadequate" speaks more to lack of knowledge on someone's part,
poor consulting on whatever level.
Patch panels were labor intensive and therefore very expensive, even so they could compete when dimmers in racks were going
for $1200 to $1500 a pop and took up a lot of real estate. dimmer prices have come down exponentially, and the cost of a patch panel
in olden times would probably equal 3 or 4 racks of 96 dimmers today. So Prof. Gress can still have his 384 dimmed circuits (or more
if he requires more although the light plot in the article uses about half of 384 circuits), its the same wiring requirement, and it seems
to me the industry is pretty much giving him a bargain. No, the fault, Jeffery, lies not within the demise of the patch panel but within
ourselves.
by the way, with regard to Prof. Gress's envy of acousticians, having worked with a number of dedicated room acousticians who
specialize in performance venues I can assure Prof. Gress that like every other member of the design team they must pay careful
attention to budget, although every once in awhile they have the opportunity to consign acoustic costs to the architecture ledger.
Interesting ideas but main thesis-not proven.
Joel E. Rubin, Ph.d.

I have never been stunned by the contents of any article in Td&T, but stunned I was by "The demise of Patch Panels-Why Your
dimmers define Your World" in the Winter 2009 issue. The article draws a fundamentally incorrect and unsupportable conclusion
that the design utility of lighting positions and "angles" in theatres has been reduced by the elimination of the patch panel and the
substitution of dimmer-Per-Circuit (dPC) systems. Among other deficiencies in logic, the author fails to identify some important facts
about modern dPC systems, to wit:
1. The introduction of dimmer-per-circuit system architecture caused an order-of-magnitude cost reduction in performance
lighting systems. This cost reduction came from the aggregate dimmer/patch panel/branch circuit installed cost vs. the dPC dimmer/
branch circuit installed cost. In part, this was because dPC dimmer racks suddenly became standardized products, unlike the handwired, labor intensive, custom patch panels and dimmer racks that preceded dPC. These cost reductions were the fundamental and
perhaps the only reason that dPC replaced patch panels and large dimmers. They allowed the deployment of many more circuits and
potentially many more lighting positions than were possible with patch panel systems. The benefits of increased subtlety of control and
design nuance, as well as decreased production labor offered by dPC systems, were only fully understood well after their adoption. The
driving force behind market acceptance of dPC was simply the huge cost reduction per circuit.
2. Since dPC systems cost much less per circuit than patch panel systems, they should have spawned larger numbers of circuits
and larger numbers of lighting positions, right? That is exactly what happened! did you ever hear of an 1100-circuit patch panel?
No, because it was not practically possible due to size and cost. However, an 1100-dimmer dPC system in a large theatre is a totally
practical proposition. On the other end of the scale, high schools that had 12 dimmers and 60 circuits now have 192 or more dimmers
and circuits. Therefore, the downward pressure on the number of lighting positions in the facilities described by the author, if true,
must have come from some other factor unrelated to the elimination of the patch panel and the installation of dPC. I suggest that budget
issues on the overall cost of construction, or marginal theatre consulting, may be two of those factors.
3. When installing a dPC system, one does not "purchase and provide power for 2,400 watts per circuit" as the author states.
Prudent engineering design and the National Electrical Code dictate that the power provided to a dimmer system must accommodate
only the connected load in a given facility, not the full "nameplate rating" of the dimmers as suggested by the author.
In his conclusion, the author asserts that the "digital age" has caused "fundamental erosion of flexibility" in lighting design.
Nothing could be further from the truth! We can now control every light in the theatre individually, we have automated fixtures and color
changers, and complex or subtle sequences of cues are now repeatable due to the introduction of computer control. We no longer have
to put up with the major compromises in control previously dictated by patch panel systems.
Sincerely, Steve Terry
Steve Terry is the VP of Research & Development at Electronic Theatre Controls. He is a USITT Fellow, and chaired
the USITT committee that developed the internationally-accepted DMX512 control protocol.

S P R I N G

2009

theatre

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Table of Contents for the Digital Edition of Theatre Design & Technology - Spring 2009