Guidelines for the Development of Power Loss Reduction Circuits of Class A Audio Amplifiers using Appropriated Voltage Adjustment Technique with Small Input Signal
doi: 10.14456/mijet.2020.7
Keywords:
Class A amplifier, krell ksa-100s, Class TD AmplifierAbstract
Audio amplifiers are the classical, commonly used electronic circuits; especially, in the applications of high wattage amplifiers; where the Class A audio amplifiers are the most acceptable and have the best sound quality. However, they would have low rate of expansion, as well as, low efficiency. For example, the famous Class A circuit model: Krell KSA-100 that consists of power amplifiers with 3 pairs of composites using the power supply plus minus 45 volts can cause high current and high power consumption all the time, i.e., with input signal voltage is zero, the circuit generates a current flowing through the final power amplifier, 1-amp pair. This results in high total current to reach 3 amps or 137 watts at all times. The researcher will conduct research to reduce the power loss in such conditions by reducing the power supply voltage more the circuit is still ready to expand the audio signal effectively as previous. Experiment by adjusting the input voltage with AC power transformer, can be adjusting from 28 to 145 volts, to allow DC power to vary the voltage in the range of 10 and 45 volts. Input 100 mVp-p input signal, 1kHz Sine wave frequency at 8-ohm load and reduced the voltage from 45 volts until the output amplifier can still maintain the input signal. Experimental results show that when reducing the power supply voltage, the power loss is reduced accordingly. Where the output signal remains distorted as the input signal is not distorted. This article describes the techniques for adjusting the voltage appropriately for Class A audio amplifiers circuit and the study of the enhancement of Class A audio amplifiers with the technique to crease the TD circuit (Tracking Class D) or DC voltage distribution circuit for the final power expansion According to the size of the audio signal received the input using a 32-bit processor as an automatic control to develop Class A audio amplifiers for better performance.
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