Diaphone & Fire Horn

Creation of the DepartmentRear view of Larkspur City Hall and Diaphone Tower
Larkspur is a city of 12,000 residents, 10 miles north of the Golden Gate Bridge in Marin County, California. Long before the Golden Gate Bridge was built an enterprising group of volunteer firemen started an outdoor dance called the Rose Bowl. The Saturday night summer dances started in 1913, and soon became a Bay Area institution that ran for 50 years.

By the 1920s, due to profits from the Rose Bowl dances, the Larkspur Volunteer Fire Department had a solid financial base. The department, without any government funding, created one of the finest equipped small-town fire departments in the United States.

About the Diaphone
Over the next decade the department purchased state-of-the-art fire engines, built a new fire station, and installed a Gamewell Fire Alarm System and a Gamewell Type B Diaphone. The west coast was a new frontier for the Gamewell Diaphone. This diaphone was one of the first installed in California. 70-plus Complete Diaphone Assemblyyears later this diaphone may still be operated manually; though it is no longer used to alert off duty paid personell nor volunteers for emergencies.

What makes this diaphone unique is simple - it has never been touched. It had operated with much of the original equipment from the auxiliary tank to the tip of the cone. The low-voltage system has continuously energized the control valve and not a single bolt or nut has ever been adjusted to the diaphone assembly itself. In all that time it has just worked. The diaphone was mounted on a custom-built tower 70 feet above the old firehouse that was located, at that time, in the basement of Larkspur City Hall.

Gamewell Box Alarm SystemFire Horn Video Clip
In the 1940s, the Larkspur Fire Department was featured on the cover of Colliers magazine and the Larkspur Fire Station and diaphone were featured in the motion picture "Impact." In the film one can get a quick look at the diaphone, the 1939 Fire Station, and the American LaFrance engine driven by Fire Chief John Raggio. The Gamewell Box Alarm System was monitored at the fire station. When a box alarm was pulled the diaphone was activated and sounded the number corresponding to the box number. In the film it happened to be Box 13. The Gamewell Diaphone and Box Alarm System continued to operate for the next 40 years.

9-1-1 Emergency Telephone System
By 1980, the 9-1-1 Emergency Telephone System had eliminated the need for the fire alarm-box type system. But, Larkspur’s Greenwell Diaphone had continued in its role as a backup system till the early 2000's. The "blast" of the diaphone could be heard seven miles away and was famous for startling people who were in the area during its daily 12:00 noon and 5:00 pm activation.

Fire Horn SoundDiaphone Operation
The diaphone operates off a six-volt system and is tied into a Simplex clock. The two supply tanks and industrial compressor provide an overabundance of compressed air through a 1.5-inch copper supply line. The pressure is reduced at the auxiliary tank high in the tower and fed to the diaphone through a 0.75-inch copper pipe. A honeybee hive occasionally inhabits the top of the tower right next to the diaphone itself. Next door is the Larkspur Fire Station and one can find the Larkspur Fire Department’s History Room there, featuring the original Gamewell catalogs, equipment, and box alarms.

In this era of high-tech digital data, thermal imagers, and laser surgery, it is fascinating that the Larkspur Fire Department’s Gamewell Diaphone remains a classic example of mechanical reliability and simplicity that still works. View more photos of the Diaphone.