【 Weak current College 】 what is power amplifier? it's composition and specification-Power By 【 China power house network 】

Power amplifier is the audio signal into audio signals and driver speaker of a device. Power amplifier plays in sound reinforcement is extremely important role, without a power amplifier, speakers will not be able to laugh, or no sound at all.



Power amplifier usually consists of 3 parts: preamplifier, drive amplifier, last stage power amplifier.

1, preamplifier with matching role, its input impedance is high (not less than 10 k Ω), you can set the front signal most absorption in the past, output impedance low (dozens of Ω), you can set the signal transmitted partial wind. At the same time, it is itself a current amplifier input voltage signals into electrical current signals, and giving appropriate amplification.

2, drive amplifier from the role of a bridge, it will send the preamplifier to current signal for further magnify, zoom into the Middle power signal driving last stage power amplifier functioning. If there is no driver amplifier, last stage power amplifier is not possible to send out a signal of high power voice.

3, the last stage power amplifier played a key role. It will drive amplifier the signal current signal power, driving the speaker, its specification determines the entire power amplifier specifications.



Power amplifier for main technical index:

1, rated power (ratepower): refers to a continuous sine wave power, enter in 1kHz sine wave and certain load, harmonic distortion of less than 1% of the output power, expressed in W/CH (Watts/channel). In General, the larger the rated power, the higher the cost.

2, total harmonic distortion (THD): refers to the higher harmonic covers fundamental wave of percentages, total harmonic distortion as small as possible, the current good power amplifier total harmonic distortion can reach 0.02%

3, the conversion rate (slewrate): unit time rising voltage range, v/µs, which reflects the power amplifier on transient sound signal tracking ability, is a transient performance indicators.

4, damping factor (dampingfactor): defined as the power amplifier load impedance (high-power tube internal resistance plus speaker wiring cable resistance), for example 8 Ω: 0.04 Ω = 200: 1, the speed of the ratio is relatively large, but not too big, too general think speaker thin, too small then you will make the sound less cloudy, sound levels, sound and image distribution.

5, output impedance (outputimpedance) (or rated load impedance): usually there are 8 Ω, 4 Ω, 2 Ω equivalence, the smaller the value, the more power amplifier load. The single, the rated load of up to 2 w power amplifier that can drive the 4 Ω impedance 8 speaker voice and distortion is very small.