Car audio speaker amplifiers

Transistors in a car amplifier take a weak current from an input deck to each speaker cone with increased force but minimal distortion.

The signal that emits from a car’s tape or CD deck or player does not have the strength to physically move the cones of a speaker. Hence no audible sound is produced. The role of an amplifier in a car is to transform weak electrical signals from a source cassette or compact disc to more powerful electrical signals that can move the cones of a speaker. The amplifier is designed to increase this electrical energy without changing its original pattern. This ensures that the sound passengers in the car hear from a speaker is the same as emanates from the source cassette. The input sound could also be from a compact disc. The amplifier works on batteries. Some systems use pre-amplifiers to build up the electrical force of the signals in stages.

Each amplifier has a system of transistors. Transistors are made of blends of materials that allow it to transmit and resist electrical current to varying degrees. Input signals are fed to the base electrode of a transistor. This base electrode transmits energy to the output electrode of the transistor. The output from a transistor steps up the force of electrical signals without disturbing the pattern. An amplifier can have more than one transistor to raise the electrical force in stages until it can move the cone of a speaker to produce audible sound. Car amplifiers can produce hundreds of watts of power.

Fidelity is an important consideration, apart from wattage, when accounting for the quality of a car amplifier. Though an amplifier is supposed to increase the power of an electrical signal without changing its nature, a certain distortion does creep in because of feedback from the output to the input. This can increase as the signal passes from transistor to transistor on its journey from the source to the speaker cone. Many passengers may be oblivious to such changes that are most often minor. Connoisseurs of music may, on the other hand, detect such changes, and be willing to pay for an amplification system that is both powerful and true to the original source signal. Non-inverting amplifiers generally have less distortion.

Amplifiers generate heat and need sinks to dissipate it. Their output should match speaker design. It is not useful for the power of an amplifier to be in excess of the speaker cone capacity. The amplifier should have a channel for each speaker that is to be installed in a car.

Amplifiers are small, unattractive and hidden from common view. It is easy to overlook their important role in adding to driving pleasure by providing pleasing sound, loud enough to shut out the traffic. It is tempting to choose a sound system for a car based on the design of the input console, the number of discs that can be carried at a time and the discreet speaker placement. Spare a thought for the humble workforce behind the show and check the amplifier specifications when you next shop for a system for your car. The salesperson is sure to take extra care to give you optimal value.