How to judge the level of the speakers

The main performance indexes speakers have?

Objective measure of performance indicators are technology speakers, we in the catalog or on the manual of speakers often see: frequency response, impedance, sensitivity, the maximum load power and maximum output level. Frequency response said speaker output level with the change of frequency, if graphed, is a HengZuoBiao frequency output pressure (or, in the db) pressure of function curve for y-coordinate. This curve in the general tendency of spectrum, of course, is the level of many for the perfect system caused by small fluctuations. In the end, the low frequency and high frequency curve fell trend, the output will be reduced, the speakers at low frequency and high frequency usually relative to the output level 3dB fell among the two point and low frequency as deadline, the deadline of the band is between two speakers of frequency range. Obviously, the frequency range is wide, so it can restore music signal wider range. For now, the frequency of the speakers, had not reached the limit, some 20kHz audio products, still far beyond the difficulty lies in frequency, general bookshelf box reached around 50-60Hz, box around 30-40Hz did very well. Additionally, the frequency range of the flat, fluctuation curves 55x55mm are expressed in the box, it's all frequency band signal can be treated, won't appear the distortion degree of balance.
Impedance popularly say, is the size of the input current signal resistance in ohms, Ω (.). Speakers are the most common impedance values Ω eight Ω, 4 and 6 Ω three, and, of course, 3, 5, 10 Ω Ω Ω other values, but not common. Special note: the speaker needs only a nominal value of the impedance of the actual size, the speaker impedance frequency is the change, such as nominal 8 Ω speakers, only in certain frequency point for 8 Ω impedance frequency, in other Ω 10, 20 for Ω, others may be low frequency and Ω or Ω 4 to 6. With the change of the characteristic impedance frequency, and the impedance curve in the box can see very clearly, this change has increased the difficulty of the amplifier. Sensitivity is measuredspeakers electricity - voice conversion efficiency index, the unit is dB/W/m, meaning for input from the power, 1W speakers axial distance can obtain the 1-m level, such as sensitivity size 90dB/W/m speakers, says the power input, sound 1W passes away to get 90dB 1-m the level. High sensitivity of the power amplifier compare save speakers, should calculate advantages. Sometimes, however, sensitivity and other performance index is under consideration, weighing, often sacrificed for the little sensitivity rather better performance, because the current power amplifier is common, the price is too high, low sensitivity is not some big problem. The maximum load power is the safety index, the speakers said the speakers can withstand the power input for the size of the input, below this threshold is obviously safety, if long time more than the limit, it is easy to voice coil overheat burned. The maximum load for this one index power safe use of speakers, we provide reference, but also should pay attention to long time this premise, the short time than the maximum load power is allowed, for example, there are many short music signals in the peak, its power than average power of several times, but even very short duration, also is fleeting, play such signals, as long as the average power does not exceed the maximum load speakers, is no problem. Maximum output level in not more than a standard distortion under the condition of the speaker's biggest pop of output capacity, is the largest can only put more speakers. Usually, the maximum output level speakers in 110dB 100dB ~, a few high output speakers can reach 120dB around. Apparently maximum output level, the higher the better, if this index is low, is prone to dynamic compression