Sound system of the main technical indicators

Sound system overall technical performance of the merits, depending on each unit's own performance is good or bad, if the system of each unit of the technical indicators are high, then the overall technical indicators of the system is very good. The main technical indicators are six: frequency response, signal to noise ratio, dynamic range, distortion, transient response, stereo separation, stereo balance.
1. Frequency response: the so-called frequency response refers to the sound equipment when the playback frequency range, and the amplitude of the sound with the frequency of the relationship. General detection of this indicator to 1000Hz frequency amplitude as a reference, and logarithmic decibels (dB) to represent the amplitude of its frequency.
Sound system, the overall frequency response of the theoretical requirements of 20-20000Hz, in practice, often due to circuit structure, component quality and other reasons, can not meet this requirement, but generally at least 32-18000Hz.
2. Signal to noise ratio: the so-called signal to noise ratio refers to the sound system of the sound source software to reproduce the sound and the whole system has a new ratio of noise, the noise are thermal noise, AC noise, mechanical noise and so on. Generally, this index is expressed as the logarithmic decibel (dB) of the rated output power of the reproduced signal and the system noise output power at the time of no signal input.
General sound signal to noise ratio of the system to be more than 85dB.
Dynamic range: Dynamic range refers to the sound system playback when the maximum distortion-free output power and static output of the system noise ratio of the logarithm of the value, which expressed in units of decibels (dB). Generally good dynamic performance of the sound system in the 100 (dB) or more.
Distortion: distortion refers to the sound system in the audio signal after the playback, compared with the original signal to the original sound source signal of some parts (waveform, frequency, etc.) has changed. Distortion of the sound system is mainly the following:
1. Harmonic Distortion: The so-called harmonic distortion is the sound system after playback of the sound signal than the original source of many more extra harmonic components, the additional harmonic component signal is the signal source frequency multiplier or frequency , Which is caused by the negative feedback network or the nonlinearity of the amplifier. Harmonic distortion of the hi-fi system should be less than 1%.
2. Intermodulation Distortion: Intermodulation distortion is a nonlinear distortion, which is more than two frequency components according to a certain percentage of mixing, modulation between the various frequency signals, through the playback device after the new non-linear signal, The signal includes the sum and difference signals between the respective signals.
3. Transient Distortion: Transient Distortion, also known as transient response, it is mainly produced when a large transient signal is suddenly added to the amplifier when the amplifier reflects the slower, so that the signal distortion. Generally after the input square wave signal through the playback device, observe whether the envelope waveform of the output signal of the amplifier is similar to the input square wave waveform to express the ability of the amplifier to follow the transient signal.
5. Stereo separation: Stereo separation of stereo sound system that left and right between the two channels of isolation, it actually reflects the left and right channels of mutual crosstalk between the two degrees. If the crosstalk between the two channels is large, the stereoscopic feeling of the reproduced sound will be weakened.
Stereo Balance: Stereo balance indicates the gain difference between the left and right channels in the stereo playback system. If the imbalance is too large, the reproduced stereo image will be offset. Generally high-quality stereo system stereo balance should be less than 1dB.