Introduction: There are two types of amplifiers commonly used in daily life: a voltage amplifier named current amplifier named current amplifier named current amplifier named current amplifier named current amplifier named current amplifier named current amplifier named current amplifier. . Constant voltage amplifier such as we often see the rural areas of the big radio; cafeteria background music player; school playground around the radio speakers; government agencies fire security system broadcasting, etc. These are fixed voltage amplifier driven. Fixed resistance amplifier such as we often go to the KTV inside the audio; bars, nightclubs, discos in the audio; home theater, square dance audio, computer desk audio, outdoor plaza professional performance audio, etc. are used fixed resistance amplifier to promote.
Difference between voltage amplifier (fixed-voltage amplifier) and current amplifier (fixed-resistance amplifier):
Fixed-voltage amplifier: also called voltage-type amplifier, is the application of a large loop voltage negative feedback, first of all to ensure that the voltage does not distort, and to minimize the internal resistance of the amplifier. The internal resistance of the amplifier as low as possible, the ideal amplifier should be a constant voltage source, with a high damping factor to control the transient response of the speaker, which is our most common fixed-voltage amplifier. Its equipment can be seen at the back of the terminals with a certain value of the voltage display.
Fixed-voltage amplifier another feature is can be transmitted over long distances, amplifiers and speakers can be far away from each other. From the circuit diagram, we can see that the output of the fixed-voltage amplifier is output by the transformer way between the speakers can measure a certain value of the AC voltage. As shown in the following circuit schematic:
Fixed resistance amplifier: also known as current power amplifier, is the application of a large loop current negative feedback, first of all, to ensure that the current is not distorted, at this time, the amplifier is a constant-current source, the internal resistance is infinite (theoretically) the damping characteristics must be bad. However, because based on the principle of electromagnetic induction analysis can be known, the voice coil in the magnet movement is controlled by the current in it. For driving inductive characteristics of the speaker system, the first to ensure that the current is not distorted, or a certain reason, because of this there is a current type amplifier development and development. The equipment behind the terminals no fixed voltage value , only marked with positive and negative and resistance marking, and some professional amplifiers behind the fixed resistance amplifier dedicated four-core socket.
Fixed-impedance amplifier also has a characteristic different from fixed-voltage amplifier, that is, fixed-impedance amplifier cannot be transmitted over long distances, so the connecting wire between amplifier and speaker is longer than the load resistance of the amplifier, which is equivalent to the increase of the load resistance of the amplifier. That is to say, the original speaker 4 ohms but due to the wire have a resistance value of the longer the greater the resistance value, the resistance value plus the original speaker's resistance value is far beyond the amplifier design load ratios, easy to match the improper and burn the amplifier. This is also when we look at the outdoor plaza professional performances, speakers and amplifiers are particularly close to the distance. At the same time in the speaker at both ends of the measurement of DC or AC, because from the circuit diagram can be seen, the speaker signal is conducted through the capacitor, the capacitor in the circuit to play a role in the isolation of direct transmission cross, is to isolate the DC transmission of AC, and this AC is not an AC voltage, but AC signals, so, when measuring the speaker ends of the voltage, with the AC file, the measured result is a constantly changing indication of the size of the indication with the preamplifier input signal, which is not the same as the signal. The size of the indication varies with the size of the input signal of the front stage. The following circuit schematic diagram shows:
Note: The above is the simplest and easiest to distinguish between the two aspects to analyze the difference between the two convenient to remember and distinguish.