The logistics behind a stereo amplifier are actually quite a bit more complex than the standard definition implies, because a number of things must happen at a precise time in order for the sound output to be sufficient.
Since many amplifiers work off of an electrical power supply , which is an alternating current, the energy flowing into the device needs to be transformed into a direct current. While the transition would not be important within many electronic devices, a stereo amplifier requires an uninterrupted source of power in order to effectively power a speaker. It is interesting to note that the faint whisper of sound coming from a record player or compact disk CD is not the actual sound that is heard by the listener.
The stereo amplifier actually takes that incoming sound and converts it into a different format that is compatible with the power required by the speakers. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products.
List of Partners vendors. Gary Altunian. Gary Altunian was a freelance contributor to Lifewire and industry veteran in consumer electronics. He passion was home audio and theater systems.
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You're in! Amplifiers can be very complex devices, with hundreds of tiny pieces, but you can get a clear picture of how an amplifier works by examining the most basic components.
In this next section, we'll look at the basic elements of amplifiers. In the last section, we saw that an amplifier's job is to take a weak audio signal and boost it to generate a signal that is powerful enough to drive a speaker. This is an accurate description when you consider the amplifier as a whole, but the process inside the amplifier is a little more complex.
In actuality, the amplifier generates a completely new output signal based on the input signal. You can understand these signals as two separate circuits. The output circuit is generated by the amplifier's power supply , which draws energy from a battery or power outlet. If the amplifier is powered by household alternating current , where the flow of charge changes directions, the power supply will convert it into direct current , where the charge always flows in the same direction.
The power supply also smoothes out the current to generate an absolutely even, uninterrupted signal. The output circuit's load the work it does is moving the speaker cone. The input circuit is the electrical audio signal recorded on tape or running in from a microphone. Its load is modifying the output circuit. It applies a varying resistance to the output circuit to re-create the voltage fluctuations of the original audio signal.
In most amplifiers, this load is too much work for the original audio signal. For this reason, the signal is first boosted by a pre-amplifier , which sends a stronger output signal to the power amplifier.
The pre-amplifier works the same basic way as the amplifier: The input circuit applies varying resistance to an output circuit generated by the power supply. Some amplifier systems use several pre-amplifiers to gradually build up to a high-voltage output signal. So how does the amplifier do this? If you look inside an amplifier for an answer, you'll only find a complex mass of wires and circuitry components.
The amplifier needs this elaborate setup to make sure each part of the audio signal is represented correctly and accurately.
Hi-fidelity output requires very precise control. All of the pieces in an amplifier are important, but you certainly don't need to examine each one to understand how an amplifier works. There are only a few elements that are crucial to the amplifier's functioning. In the next section, we'll see how these elements come together in a very basic amplifier design. The component at the heart of most amplifiers is the transistor. The main elements in a transistor are semiconductors , materials with varying ability to conduct electric current.
Typically, a semiconductor is made of a poor conductor, such as silicon , that has had impurities atoms of another material added to it. The process of adding impurities is called doping. In pure silicon, all of the silicon atoms bond perfectly to their neighbors, leaving no free electrons to conduct electric current.
In doped silicon, additional atoms change the balance, either adding free electrons or creating holes where electrons can go. Electrical charge moves when electrons move from hole to hole, so either one of these additions will make the material more conductive. See How Semiconductors Work for a full explanation. N-type semiconductors are characterized by extra electrons which have a negative charge.
P-type semiconductors have an abundance of extra holes which have a positive charge. Let's look at an amplifier built around a basic bipolar-junction transistor. This sort of transistor consists of three semiconductor layers -- in this case, a p-type semiconductor sandwiched between two n-type semiconductors.
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