WPS-4000

Whelen WPS-4000 series
Whelen WPS-4004
Company	Whelen Engineering
Produced	1988-present 1988-2003 (WPS-4008)
Type	Rotational Electronic
Sound output	118-133 dB @ 100 ft
Wattage	400-3200 W
Voltage	28 V DC
Preceded by	Whelen WS-3000
Documentation	Manual

The WPS-4000 is Whelen Engineering's most popular and longest-lived series of rotating electronic sirens and currently the only rotating electronic siren on the market. The series has gone through many changes throughout the years and is known for its sound output and voice clarity.

Today, Whelen still sells the WPS-4003, WPS-4004, and the VORTEXR1, VORTEXR2, VORTEXR3, and VORTEXR4, with the WPS-4004 and VORTEXR4 being the most popular options. WPS-4000 series sirens can be found all across the United States and is a very common choice by cities to replace aging existing systems of sirens which lack voice and battery backup capabilities along with the WPS-2900, as well as cities looking for a brand-new system. They are known for their impressive sound output, and voice clarity. However, they also have gained a reputation for reliability issues when they aren't maintained properly and are prone to battery failure. Still, they have earned their place as the dominant rotational electronic sirens in the market.

History and design

WPS-4008 (WPS-4000)

The WPS-4000 series began in 1988, with the introduction of the WPS-4000. The WPS-3000 was selling well and was matching the performance of several mechanical sirens on the market, but it required 16 individual drivers which drove up maintenance and production costs. Whelen opted to use their new 400 W "Superpower" drivers from the WPS-2700 series and placed them into a rotational siren, with a total of 8 400 W drivers per siren.

Reusing the "throat and horn" design concept from the WPS-3000, the siren had eight vertically aligned throats that converged into a single large fiberglass projector, with the drivers being located at the rear of each throat inside a vertical rear housing. The housing also covers both the top and bottom of the siren, protecting the throats from the elements. The projector itself was largely reused from the WPS-3000 with minimal changes. All of this allowed the siren to reach 130 dB at 100 feet, which to this day is still the loudest single electronic siren produced.

The WPS-4000 used a different, cube-shaped direct-drive rotator from the WPS-3000, using a microswitch based sensor to tell the controller which direction the projector is facing. They could be synchronized remotely with other WPS-3000 and 4000 units to have them all face the same direction during voice messages, preventing the sounds from clashing and ruining voice clarity. Like the WPS-3000, the drivers are hard-wired to the amplifiers, and do not use brushes, which improves sound quality. Instead of rotating fully, the WPS-4000 oscillates 360 degrees, reversing direction when it reaches its "home" position. It will also reset to this "home" position before conducting voice messages.

Upon the introduction of the WPS-4000-4 and WPS-4000-3 in 1990, the WPS-4000 was renamed to the WPS-4000-8 to differentiate itself from the smaller models. The WPS-4000-8 was then renamed once more to the WPS-4008 between 1999 and 2000. The WPS-4008 would eventually be discontinued in 2003, due to low sales and a lack of cost to performance compared to the smaller models. These sirens are quite rare to find in service today, often being replaced by newer WPS-4004 units.

A dual headed model known as the WPS-4000-II was also created, using two non-rotational WPS-4000 heads mounted on a single rotator by attaching them together. Its overall design somewhat resembled the ACA Alertronic 5000. It was able to be mounted on top of a trailer for mobile use, and likely could be pole mounted as well. The two heads faced the same direction. The WPS-4000-II reached 133 dB at 100 feet, which made it the loudest electronic siren ever made, but it was too expensive and impractical and only a handful of these were ever produced. None are known to survive today.

WPS-4004 and VORTEX

A representation of a Whelen Vortex Finback.

In 1990, two more sirens would be introduced, the WPS-4000-3 and the WPS-4000-4. These were essentially a WPS-4000 cut in half, with 3 and 4 400 W speaker drivers each, reaching 124 dB and 126 dB at 100 ft, respectively. These lacked the covers above and below the throats, as well as the horizontal strut on the projector. The WPS-4000 itself would be renamed to the WPS-4000-8. Everything else about these two sirens were identical to the WPS-4000-8. Also introduced around 1990 was the WS-404R, which was a tone-only variant of the WPS-4000-4 which lacked voice capabilities and was meant to be a more affordable option.

In 1995, the WPS-4000-3, WPS-4000-4 and WPS-404R would receive a visual overhaul. The mesh screen was moved from the very front of the projector to about halfway inside of it, and the X shaped support struts were removed. The bulges on the sides of the projector were also removed. It was at this time that the WS-404R would be renamed to the VORTEX, with a cheaper 3-driver model being introduced alongside the 4-driver model. Some VORTEX sirens came equipped with a large fin attached to the driver housing, likely to aid the siren's rotation in high winds. This would only be installed on earlier units, with later VORTEXes lacking the tailfin. These are often referred to as "Finback" VORTEXes by enthusiasts.

The VORTEX also received a different rectangular rotator, which lacked the quadrant control and indexing features, and was originally belt-driven instead of direct-drive. Originally it used a very simple rectangular design resembling those used on early WS-3000 units, before later being updated to its current, more complex shape. The new rotator design uses a direct-drive gear driven rotator, which is more reliable than the older belt-driven rotators. This rotator would also be used on Whelen's HORNET siren.

Around 1999 or 2000, the names of the sirens would be overhauled. The WPS-4000-3, WPS-4000-4 and WPS-4000-8 would be renamed to the WPS-4003, WPS-4004 and WPS-4008, respectively. Additionally, in 2002 the VORTEX sirens would be renamed to the VORTEXR series, and a 2-driver model was introduced. In 2003, the WPS-4008 would be discontinued due to costs and lack of sales, as its price did not justify its performance compared to the WPS-4004. The final addition was in 2010 with the introduction of the VORTEXR1, a single driver model of the VORTEXR, with performance matching the HORNET. The WPS-4004 and VORTEXR are compatible with Whelen's VisuAlert visual warning beacons.

Model	Image	Output	Drivers	Notes
WPS4003		127 dBc	3	WPS4003 Product Sheet
WPS4004		129 dBc	4	WPS4004 Product Sheet
WPS4008		130 dBc	8	WPS4008 Product Sheet