But the true calling of power amplifiers is not decibels, but sound quality.
Ask how we lived without amplifiers before? Well, before there was a lot of things … And modest power amplifiers were hiding in the bowels of radios and radio tape recorders: plug in speakers and listen to your health. And now almost every head unit is equipped with built-in amplifiers - these include advertising promises of the type “4 to 45 W!” Only a few prestigious models, called decks, arrogantly declare that there are no amplifiers in them - they say, we are from high society … And all because the built-in amplifiers really can not jump above their heads.
This is mainly connected … with the supply voltage! If the car is standing with the engine turned off in a quiet courtyard, then listening to Chopin in it is very nice - it's almost like home. But it’s worth starting up the engine and driving out onto the street, as you know - the area is too noisy, and Chopin disappeared somewhere. You turn up the volume - at first it helps, but gradually instead of pleasure you begin to feel irritation. Still - with an increase in the output power, the level of signal distortion sharply increases, but the ear does not tolerate this. And the higher the class of equipment, the higher the comfortable sound volume that we set.
What does the supply voltage have to do with it? So the maximum that the built-in power amplifier can count on is 14.4 V! Take away the voltage drop at the output transistors, even if they are the most-most, estimate the amplitude of the output signal - no, a lot will not work. And the level of distortion at an output power of 35 W easily reaches 20% instead of an acceptable 0.1% - this is no longer music or even cacophony, but just nasty noise. The microcircuit of the built-in amplifier really squeezes out 18 … well, 20-22 W of “normal music” - no more. And to go further, you first need to increase the supply voltage - otherwise, where does the undistorted output signal come from? And external power amplifiers cope with this task. Roughly speaking, the better (read, the heavier!) The power supply unit of such an amplifier, the better it should work.
But what about the growth of distortion? Nobody canceled it, but in serious amplifiers it reaches unpleasant values much later - therefore hundreds of watts of undistorted power promised by manufacturers, as a rule, are quite real. But those who want to talk with the seller or installer about the nuances of circuit solutions of different amplifiers will have to dig deep into the books on radio electronics - otherwise the enthusiastic stories of specialists about class A, AB and D amplifiers will remain, to put it mildly, misunderstood.
However, something can be figured out without special training. For example, amplifiers differ in the number of channels - this does not need to be explained. A single-channel amplifier will serve, for example, only a subwoofer, but a five-channel amplifier will also pull front and rear speakers. The prices of amplifiers on the market are in the widest range: from about $ 60 to $ 5, 500 - from consumer goods to an expensive “exclusive”. To some extent, the price of an amplifier reflects its quality, although different companies understand this differently. Say, American manufacturers love everything “big” - both engine displacement and amplifier power: for your money, you always get solid watts from them. But the Italians profess a different “faith”: whatever the producer, then Guarneri or Stradivarius, who professes their own approach to music. There are fewer capacities there, but as for the cunning circuitry crowned with almost gold, be sure. Among the most famous names on the market, we note the American Soundstream Tarantula and Rockford Fosgate, the English Genesis Monoblock, the Swedish DLS A7 and Audison, as well as the Italian Altomobile.