Few brands are as closely associated with the history of the American car radio as DELCO. For decades, DELCO radios were fitted to Cadillac, Chevrolet, Buick, Oldsmobile, Pontiac and Corvette models. Yet DELCO was far more than just a supplier. The company played a major role in shaping the development of the car radio – from early vacuum-tube receivers and automatic station-seeking systems to transistor, FM and stereo radios.
THE BEGINNINGS
DELCO’s radio history began in the late 1920s. In 1929, General Motors founded the General Motors Radio Corporation with the aim, among other things, of advancing radio technology specifically for use in automobiles. These early car radios were still far removed from the compact units that would follow in later decades. The actual receiver was large and was usually mounted behind or underneath the dashboard, while the controls were operated through mechanical linkages.
From the mid-1930s onward, General Motors increasingly developed radios designed specifically for installation in the dashboard. In 1936, production began in Kokomo, Indiana, under the DELCO Radio Division. This marked the transition of the car radio from an optional accessory to an integral part of the automobile.
the signal seeking radio
One of DELCO’s most important innovations was the automatic station-seeking system.
In 1947, DELCO introduced a Signal-Seeking Tuner. Instead of searching for a station manually with the tuning knob, the driver could activate an automatic search function. An electric motor moved the tuning mechanism across the frequency band while the radio circuitry monitored the incoming signal. When a sufficiently strong station was detected, the radio stopped automatically. In principle, this was already very similar to the SEEK function found in modern radios – except that the entire process was carried out electromechanically.
the legend: the wonderbar radio
In the early 1950s, the automatic station-seeking system increasingly found its way into General Motors vehicles. The technology eventually became best known under the name WONDERBAR – and for many readers, it will probably now become clear where the name of our company comes from.
The large horizontal bar on the radio was far more than a design feature. Pressing the WONDERBAR activated the automatic station-seeking function. The tuning pointer moved across the dial until the radio detected a sufficiently strong station, at which point the mechanism stopped automatically. For the 1950s, this was an exceptionally advanced convenience feature. The WONDERBAR quickly became a characteristic feature of premium American car radios, particularly in Cadillac, Chevrolet, Buick, Pontiac and Oldsmobile models.
from tube to transistor
At the same time, DELCO continued to advance the electronics of its radios.
Early units operated entirely with vacuum tubes. Because these required high operating voltages, elaborate voltage converters and so-called vibrators had to be used. By the mid-1950s, DELCO increasingly began incorporating transistors into its radios.
In 1957, one of DELCO’s early fully transistorized car radios was developed for the Cadillac Eldorado Brougham. This marked the beginning of the end of the classic vacuum-tube era.
Transistors required less space and energy and generated significantly less heat – ideal characteristics for use in automobiles.
AM/FM and Stereo
In the early 1960s, the next major step followed.
DELCO developed combined AM/FM car radios, which became available for various General Motors models from 1963 onward. FM offered significantly better sound quality and less interference than the AM radio that had dominated until then.
Soon afterward, stereo systems and additional loudspeakers were introduced. The simple car radio was gradually evolving into a true in-car audio system.
WHY DELCO RADIOS ARE STILL SO FASCINATING TODAY
Classic DELCO radios are far more than just historic entertainment electronics. They demonstrate how engineers, long before the age of microprocessors, created complex convenience features using mechanics, relays and analog electronics. The DELCO WONDERBAR in particular perfectly represents this era.