Car amplifier into four categories: CPI (A), CPI (B) (B), and B (AB) class, digital (D) category.
CPI (A) of the amplifier output transistor (or tube) in which the operating point of the midpoint of the linear portion, regardless of how changes in the signal level, it is removed from the power supply current is always constant, it is inefficient, as a when the amplitude of the audio signal is amplified due to changing, the actual efficiency is unlikely to exceed 25%, or by a single push-pull pipe work. Advantages CPI amplifier is no crossover distortion and switch distortion and harmonic component is mainly even harmonics, in the sense of hearing the bass thick, warm and supple tenor, treble clear and neat, well layered, and very likable . But has since more power consumption, low efficiency, easy to heat and cooling requirements for high and has not been widely used in high-power amplifier. Because the device long-term work at high temperature and high current, easily lead to reliability problems and aspects of life, and the high cost of the machine, so manufacturers CPI amplifier known manufacturers, is now mostly discontinued transistor Class A amplifier.
Bias B (B) of the push-pull amplifier transistors work (or tube) in the absence of a drive signal in a low current state, when coupled with the drive signal, a pair of tubes within a half cycle of current rise and another child just tended deadline, to the other half, the situation is the opposite, since the two work in rotation, push-pull circuit must be used to amplify the complete signal waveform. B amplifier advantage of higher efficiency, theoretically up to 78%, the disadvantage is large distortion.
Class A and B (AB) amplifier driven low, the amplifier is a Class A operation, when increasing the drive level, the Switch B work. Class AB amplifier Bijia class’s strengths is that it improves the efficiency of the small signal is input, as the output power increases, efficiency is increased, although large distortion Bijia class, however, is still the most widely used program transistor amplifier tend more and more high-bias class AB, in order to reduce the distortion of low level signals. Most car amplifiers are now in this way.
Digital (D) amplifier with traditional analog amplifier are two different works, it belongs to switching audio amplifier, Class D using PWM technology, is a switching frequency with clock period varies amplifier. In high power applications, digital amplifier also has a wide frequency response, wide dynamic range and excellent transient response. His advantage is that distortion, anti-interference ability, small sink area, small size, light weight, low power consumption, high conversion efficiency, class AB sound quality. At present, the cost is more expensive, although the cost of development is now reduced hardware and software technology, digital amplifier applications will be more and more.
Post time: Apr-04-2016