When designing and installing a sound system, there is a problem with the distribution of the amplifier and the speaker. In terms of tone, pay attention to its collocation is undesirable, soft hard moderate changes in temperature, finally make a complete set of equipment to restore timbre is neutral, it only from the art into consideration. From the technical aspect to consider the elements of power amplifier and speakers are: a, power match, second, the power capacity matching, three, impedance matching, four, the matching of damping coefficient. If we recognize these four points in the match, the performance of the equipment can be fully and maximised. 

Power match 

For high fidelity listening, the rated power should be determined according to the best sound pressure. We all feel this way: the volume hours, voice weakness, thin, dynamic, and you won't come without burnish, low-frequency significant lack, poor fullness, voice seemed to shrink in the inside out. When the volume is appropriate, the sound is natural, clear, round, soft and plump, strong and dynamic. But when the volume is too loud, the sound is not soft, rough, and earthing. So heavy burst pressure level have A great relationship with the sound quality, regulations, listen to the tone of the sound pressure level is best for 80 ~ 85 db (A), we can the distance from the listening to register to the speaker and the speaker of the characteristics of sensitivity to calculate the power rating of the rated power and power amplifier. 

Power reserves match 

Speakers: to make it withstand the shock of the sudden burst of the program signal without damage or distortion. Here is an empirical value for reference: the selected sound box nominal power should be three times as high as the theoretical calculation. 

Amplifier: the power reserve required is different than that of a transistor. This is because the electron tube has a smooth overcharge curve. At the peak of the music signal, the electron tube amplification does not obviously produce the clipping phenomenon, only the tip of the peak is turned round. This is what we call flexible clipping. When the transistor has been in charge, the non-linear distortion rapidly increases, causing the signal to be seriously clipped, it is not to make the peak circle but to cut it neatly. A combination impedance analog loudspeaker with resistance, inductance and capacitance is used to test the actual output ability of several high quality transistors. The results show that in the case of phase shift in load, there is a single nominal 100W amplifier, and the actual output power is only 5W when the distortion is 1%. 

For the system's average sound pressure level and the loudest pressure level should be left. The content of the show and the working environment should be determined. The redundancy minimum 10 db, for modern pop music, disco dancing, such as music, you will need to have 20 ~ 25 db redundancy, so that it can make sound system security, stability. 

Impedance matching 

It is the nominal output impedance of the amplifier, which should be consistent with the rated impedance of the speaker. At this point, the power amplifier is in a state of optimal design load line, so can give maximum not distortion power, if the speaker rated impedance is greater than the rated output impedance of the power amplifier, power amplifier of actual power output will be less than the rated power output. If the speaker rated impedance is less than the rated output impedance of the power amplifier, stereo system can work, but the power amplifier is in danger of overload, require amplifiers have perfect over-current protection measures to deal with, more strict requirements for vacuum tube amplifier impedance matching. 

The matching of the damping coefficient 

The damping coefficient KD is defined as: KD = power output impedance (equal to sound box rated impedance)/power output internal resistance. 

The KD value determines the amount of electrical damping that the speaker is affected by the fact that the internal resistance of the amplifier is actually an electrical damper for the speaker. KD value, the greater the electrical damping is heavier, of course, KD values of the power amplifier is not the bigger the better, the KD values will make the speaker electrical damping is overweight, so that make the pulse front set up time, reduce the index of transient response. Therefore, it should not be a one-sided pursuit of the big KD values when selecting the power. As household high-fidelity amplifier damping coefficient have a experience for reference, the minimum requirements: transistor amplifiers KD values greater than or equal to 40, vacuum tube amplifiers KD values greater than or equal to 6. 

Guarantee with the steady and transient characteristics of the basic condition of good, should pay attention to the speakers mechanical quality factor (Qm) and equivalent damping coefficient of the amplifier (KD) to cooperate, it will sound box feeder as part of the sound system as a whole to consider. The supply lines of the speakers should be small enough to be negligible compared to the rated impedance of the speakers. The power loss should be less than 0.5 dB (about 12%).