The Power of the Amplifier Matches the Power of the Speaker

- Oct 17, 2018-

1. Power matching

In order to achieve high fidelity listening requirements, the rated power should be determined based on the preferred listening sound pressure. We all have the feeling that the volume is small, the sound is weak, the thinness, the dynamic can't come out, the dullness, the low frequency is obviously lacking, the fullness is poor, and the sound seems to shrink in the inside. When the volume is right, the sound is natural, clear, round, soft, full, powerful, and dynamic. However, when the volume is too large, the sound is not soft, rough, and has a feeling of being rooted. Therefore, the sound pressure level of the playback has a great relationship with the sound quality. The sound pressure level of the listening area is preferably 80~85dB (A weighting).

2. Impedance matching

Simply put, the rated output impedance of the amplifier should match the rated impedance of the speaker. At this point, the power amplifier is in a better design load line state, so it can give a larger undistorted power. If the rated impedance of the speaker is greater than the rated output impedance of the power amplifier, the actual output power of the power amplifier will be less than the rated output power. If the rated impedance of the speaker is less than the rated output impedance of the amplifier, the sound system can work, but the power amplifier has the danger of overload, and the power amplifier is required to have perfect over-current protection measures to solve the problem. For the tube amp, the impedance matching requirement is stricter.

3. Matching of damping coefficient

The damping coefficient KD is defined as: KD = rated output impedance of the amplifier (equal to the rated impedance of the speaker) / internal resistance of the amplifier output.

Since the internal resistance of the amplifier output has actually become the resistor of the speaker, the KD value determines the amount of resistance the speaker receives. The larger the KD value is, the heavier the resistance is. Of course, the KD value of the power amplifier is not as large as possible. If the KD value is too large, the speaker resistance is too heavy, so that the pulse front time is established and the transient response index is lowered. Therefore, when selecting an amplifier, one should not pursue a large KD value. As a household high-fidelity power amplifier damping coefficient has an empirical value for reference, lower requirements: transistor power amplifier KD value is greater than or equal to 40, tube amplifier KD value is greater than or equal to 6.

4. Sensitivity matching

The output power of the amplifier is not equal to the driving force of the speaker. The strong driving force is related to the output power of the amplifier, and it is also related to many other factors, especially the sensitivity of the speaker. Speaker sensitivity is an important factor in determining the power output of a power amplifier. One definition of speaker sensitivity is: send 1W of electric power to the speaker, and the sound pressure (dB) can be obtained in 1 meter on the front axis of the speaker, in dB/W/m.

5. Tone matching

The tone adaptation means that the sounds of the amplifier and the speakers should be properly matched to each other to obtain the playback sounds that the user likes. The sound of the equipment is subjective, different people love different sounds, personality, hobbies, cultural accomplishments and experiences all affect the listener's preference for the sound. Due to the historical changes and national cultures of different countries, audio equipment in different countries also has different timbre characteristics.

 

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