Reprinted from
Car audio - Wikipedia, the free encyclopedia
"History
From the earliest days of radio, enthusiasts had adapted domestic equipment to use in their cars but the commercial introduction of the fitted car radio came in the 1930s from the Galvin Manufacturing Corporation. Galvin Manufacturing was owned and operated by Paul V. Galvin and his brother Joseph E. Galvin. The Galvin brothers purchased a battery eliminator business in 1928 and the corporation’s first product was a battery eliminator that allowed battery-powered radios to run on standard household electric current. In 1930, the Galvin Corporation introduced the first commercial car radio, the Motorola model 5T71, which sold for between $110 and $130 and could be installed in most popular automobiles. Founders Paul Galvin and Joe Galvin came up with the name 'Motorola' when his company started manufacturing car radios. A number of early companies making phonographs, radios, and other audio equipment in the early 20th century used the suffix "-ola," the most famous being Victrola; RCA made a "radiola"; there was also a company that made jukeboxes called Rock-Ola, and a film editing device called a Moviola. The Motorola prefix "motor-" was chosen because the company's initial focus was in automotive electronics.
In Germany Blaupunkt fitted their first radio to a Studebaker in 1932 and in the United Kingdom Crossley offered a factory fitted wireless in their 10 hp models from 1933.
The early car radio receivers used the battery voltage (6.3 Volts at the time) to run the filaments, and generated the required high voltage using a vibrator to drive a step up transformer. The receivers required more stages than the typical home receiver in order to ensure that enough gain was available to allow the AGC to mask signal fading as the car was driven around.
When cars switched to 12 Volt batteries, the same arrangement was used, with tubes with 12-volt heaters.
In 1952 Blaupunkt became the first maker to offer FM receivers.
A common feature of modern car radios is the Seek function which allows tuning from one station to the next at the push of a button. It may be a surprise to some that this facility was a popular option on some Ford products in the 1950s. It was known as the "Town & Country" radio since it used a pair of switches marked "Town" and "Country." Pressing the Town button actuated a motor to rotate the tuning mechanism while the receiver sensitivity was reduced so that only local (stronger) signals would be received. When a station was tuned, the motor stopped. Pressing the Country button had the same effect except that full sensitivity was enabled so that the very next available station would be selected. In addition, for repeated seeking operations, pressing a foot switch on the driver's floor up to the left where the "dead pedal" is located on modern cars would reactivate the Seek at whatever sensitivity was last selected.
The introduction of semiconductors allowed the output stage to change to a transistor, which soon lead to the elimination of the vibrator, and the use of "Space Charge" tubes that only required 12 volts on their plates.
Advances in electronics allowed additions to the basic radio and Motorola offered 45 rpm disc players fitted to some Chryslers from as early as 1956. Tape players using reel to reel equipment followed but their bulk ensured popularity was limited but this changed in 1964 when Philips launched the Compact Cassette. Other early manufacturers and enthusiasts began building extra audio amplifiers to run on 12 volts (the standard voltage in automotive electrical systems). Jim Fosgate, later to become the founder of Rockford Fosgate, was one such pioneer. The company a/d/s also brought an amplifier to market in 1978.
At first, speakers from the home audio and professional markets were simply installed into vehicles. However, they were not well suited to the extremes of temperature and vibration which are a normal part of the environment of an automobile. Modified drivers were developed to cope with these factors.
Today, advances in acoustic technology mean that even two 10-inch speakers in a well-designed efficient enclosure can produce more than 100 decibels SPL (sound pressure level) within the cabin.
Car audio competitions started in the early 1980s in a quest to find the loudest and/or most outrageous installations. For example, in 1985, Wayne Harris famously modified a 1960 Cadillac Hearse to feature several 32-inch subwoofers. Little consideration was given to sound quality early on, but in the early 1990s, several organizations, including IASCA, began car audio competitions focusing on sound quality. The two styles -- SPL vs. sound quality -- have become almost mutually exclusive. The loudness competitions have become known as dB drag racing."
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