Understand Speaker Performance Indicators

- Mar 18, 2020-

I. Power


1.Rated power


Rated power, that is, long-term power, means that it will not be damaged in long-term use under this power state. It refers to the power of the speaker without damage for more than 8 hours of continuous operation without distortion. This power is nominally of practical use.


2.Bearing power


The carrying capacity of the speaker means "the input speaker will not be damaged if it exceeds the indicated power, and it can withstand it". It refers to the average power of the signal allowed to be applied to the speaker input under the condition that the speaker is allowed to have some distortion. A speaker unit with a large carrying power is not easy to be distorted by the high power provided by the amplifier, and can have a better performance when listening to explosive music; and, the speaker needs to cooperate with the amplifier to provide a larger sound pressure, and It's not that loud speakers with high power must be "sounding."


3.Peak power


Refers to the maximum power that the speaker can withstand in a short time. It refers to the maximum strong pulse that the equipment can withstand within 1/100 seconds, that is, within 10 milliseconds, and the equipment is not burned. This power is usually 4 times the rated power. The speaker's ability to withstand peak power is conditionally limited. The time setting is 1 second, and it can only be repeated 10 times. If it is exceeded, it may be damaged. The speaker marked with peak power must be used with extreme caution. 1/4 of the power.


Second, the signal-to-noise ratio


Signal to noise ratio, SNR (Signal to

Noise Ratio) is also called the signal-to-noise ratio, which is the ratio of the voltage of the output signal of the amplifier to the noise voltage output at the same time, often expressed in decibels. The higher the signal-to-noise ratio of a device, the less noise it produces. Generally speaking, the larger the signal-to-noise ratio, the smaller the noise mixed in the signal, the higher the sound quality of the sound playback, otherwise the opposite. The signal-to-noise ratio should generally not be lower than 70dB, and the signal-to-noise ratio of high-fidelity speakers should reach more than 110dB.


The signal-to-noise ratio is the ratio of the normal sound signal played back by the speaker to the noise signal (power) when there is no signal. Expressed in dB. For example, the signal-to-noise ratio of a speaker is 80dB, that is, the output signal power is 80dB greater than the noise power. The higher the SNR value, the smaller the noise. In order to ensure the sound effect, it is recommended that speakers with a signal-to-noise ratio of more than 80dB can be included in the purchase range.


Frequency response


The frequency response range of the speaker refers to the frequency response width of the audio signal that the speaker can reproduce under the rated power state and within a specified amplitude variation range when the audio signal is reproduced. In simple terms, it is the range between the lowest and highest sounds that a speaker can emit. Generally speaking, under the specified power condition of the amplifier, the high and low-end gains of the frequency are reduced by -3dB, and the frequency bandwidth between the two points is called the frequency response range of the amplifier.


This indicator reflects the main frequency range of the speaker. The wider the range, the better the sound reproduction characteristics (under the same conditions as other related indicators). The range that human hearing can reach is about 20Hz-20KHz. Within the rated frequency range, the ratio of the maximum value to the minimum value of the output voltage amplitude is expressed in decibels (dB). People with sounds below 20Hz can't perceive through their ears, they can only feel through other organs.


4.sensitivity


Sensitivity refers to the sound pressure level measured at 1m in the axial direction when the speaker adds a pink noise signal voltage equivalent to 1W power at the rated impedance. The sensitivity of a speaker determines whether the speaker is efficient. High sensitivity speakers can save the output power of the power amplifier under the same sound pressure level, and vice versa. The low-frequency response of high-sensitivity speakers is relatively poor. The low-sensitivity speakers consume power and have good low-frequency response.


5.distortion


The concept of speaker distortion and amplifier distortion is basically the same, except that the amplifier inputs an electrical signal and outputs an electrical signal, while the speaker inputs an electrical signal and outputs a sound wave signal, so the distortion of the speaker is an electrical signal. The amount of distortion that occurs when switching between a signal and a sound signal. The distortion level index is just a more general statement. It should be divided into three types: harmonic distortion, mutual decay distortion, and transient distortion.


Harmonic distortion refers to the distortion caused by the addition of higher harmonic components that are not present in the original signal. Intermodulation distortion mainly affects the tonal aspect of the sound. Transient distortion is because the speaker has a certain inertial mass. The vibration of the basin can't keep up with the vibration of the electrical signal that changes instantaneously, resulting in the difference between the original signal and the playback sound. It is a very important indicator in speakers and speaker systems, which directly affects the degree of reproduction of sound quality, so this indicator is closely related to the quality of the speakers. Often expressed as a percentage, the smaller the value, the smaller the distortion. The distortion of ordinary multimedia speakers is preferably less than 0.5%, and the distortion of subwoofers is generally large, and less than 5% is acceptable.


6. impedance


This indicator indicates the ratio of the voltage and current of the input signal of the speaker. There are many types of speaker input impedance. Generally speaking, higher impedance than 16Ω is considered as high impedance, and lower impedance is considered as lower impedance. The standard impedance of the speaker is 8Ω. Under the condition that the power amplifier and output power are the same, low impedance speakers can get more Large output power, but the impedance is too low will cause under-damping and bass degradation. So although this indicator has nothing to do with the performance of the speakers, it is best not to buy speakers with low impedance. The recommended value is the standard 8Ω. The impedance of headphones is generally high impedance-32Ω is very common. The impedance of a power amplifier can generally be labeled as an equivalent impedance. For example, an output of 130W at 4Ω is equivalent to an equivalent output of 8Ω80W. It is not good when it is large, and it is not good when it is small. The input impedance of the speaker must match the output impedance of the amplifier. If it refers to the input impedance of the power amplifier, it should be higher, which will help improve the anti-interference ability of the system.


7.crossover point


Crossover point refers to the dividing point between the high-pass, band-pass, and low-pass filters of the frequency divider. It is usually expressed by frequency, and the unit is hertz. The high- and low-frequency two-way speakers have only one frequency division point, and the high, middle, and low three-way speakers have two frequency division points. The frequency division points should be specifically determined according to the frequency characteristics and power allocation of each frequency band speaker unit or speaker.


The crossover point is a mark of the frequency response range that the crossover assigns to each speaker unit. It is based on the audio performance of the speaker unit (the boundary frequency determined by the effective diameter of the unit diaphragm); for example, high-frequency units and The frequency division point of the intermediate frequency unit is usually 3000Hz ~ 4000Hz, the frequency division point of the intermediate frequency unit and the low frequency unit is usually around 400Hz, and the frequency division point of the subwoofer unit is usually 150Hz or even lower.


The more crossover points of a speaker prove that the speaker's audio performance range is larger and the speaker unit is more. It is easy to make a speaker, but it is difficult to make a speaker, especially a speaker with a frequency of three or more. Under the premise of ensuring the high quality of the speaker unit, the quality of the frequency divider has become the main indicator of whether the speaker is up-grade. , Good crossover strives to be precise, the art is endless. In the case of three frequency division, the farther the two frequency division points should be separated (should be more than three octave bands), the better the system response after combination is.