Whelen Drivers

[Rory Buszka]

Two years ago, when I went to interview for an internship at Community Professional Loudspeakers, Inc. in Chester, PA (south of Philly), I was surprised to discover the company had a direct link with Whelen Engineering's line of electronic outdoor warning sirens, from the development of the fiberglass directional and omnidirectional horns for the WPS-series sirens, to testing of competitive siren drivers. At the time, there was no publicly available documentation of the relationship between Community and Whelen Engineering, so I was bound by a NDA from disclosing any details. Now, in Community's 40th-anniversary article, they describe how the relationship with Whelen came to be, and how it continues to this day.

Here's a reprint of that section of the article, subtitled "The Siren's Song".

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Community?s growing reputation for intelligibility
and power resulted in another unusual,
if somewhat tangential partnership. As Bruce
explains it, ?We had been approached by a
company named Whelen Engineering in Connecticut,
which was involved in the emergency
outdoor early warning systems market.
Up to that point, the early warning systems
in place used mechanical sirens, which were
by far the loudest and most cost-effective
option, but lacked the ability to communicate
anything specific. Whelen was interested in
creating a loudspeaker that could compete
with the levels of a siren, yet provide speech
communication.?

John takes up the story. ?After the nuclear
near-meltdown incident at Pennsylvania?s
Three Mile Island facility in 1979, the federal
government had issued a mandate ordering
voice warning evacuation systems in heavily
populated areas. We worked with Whelen
to build a high-powered horn with 45-degree
horizontal coverage, that could repeat a
message eight times for 360-degree coverage.
Their goal was to have a loudspeaker
that was capable of achieving the levels of a
pneumatic air raid siren, somewhere around
153dB at one meter. We did additional environmental
testing in a wind tunnel against 150
MPH winds, and created a horn design that
met, and exceeded all applicable standards.?
Whelen returned soon after to ask for more
designs, including a 1000 Watt compression
driver, and mass notification/emergency management
systems became an integral part of
Community?s business. The relationship with
Whelen continues to this day.
The project reaped other long-term benefits
as well. ?Through our research in designing
ultra-high powered transducer technology for
Whelen, we gained tremendous insight into
thermal conductivity and reliability,? Bruce
observes. ?These are components that are
being driven a whole lot harder than any
commercial loudspeakers. We were able to
apply much of what we learned to the design
of commercial speakers.?

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I believe that siren signals, not voice messages, are still the way to transmit a warning clearly and effectively to all constituents of an outdoor warning system, because they have very little time-dependent content, so intelligibility will not be a concern. However, I feel strongly that as electronic outdoor warning sirens go, Whelen sirens are still a cut above the competition from Federal Signal, American Signal Corp., and ATI.