Weak current College】 【audio amplifier and English terminology.

<br> <br> Output power (outputpower): indicates that the power amplifier in a certain load output power, usually in the amplifier specifications marked in 8 ohm load, 4 ohm load or 2-ohm load state of output power, but also .indicates that the power amplifier in Bridge mode, 8 ohm load or 4 ohm load the output power. The output indicates that the amplifier's rated output power, not the maximum or peak output power. <br> <br> Load impedance (loadimpedance): .indicates that the power amplifier load capability, the smaller the load impedance, indicating that the amplifier can ability through the current, generally speaking, the majority of the stronger amplifier minimum load impedance 4 ohm, good quality minimum load of the amplifier is 2 ohm in .General. Dual channel to load 4 ohm power amplifier in Bridge mode can load minimum 8 ohm, 2-channel is able to load 2 ohm amp, bridging State can load 4 ohm. Bridging State can only load 8 ohm power amplifier, no load lower .impedance, otherwise it will build successfully placed because excessive current and burned. <br> Stereo (2ch) mode (stereomodeordualmode): general power amplifier with two separate amplifier circuit, can accept two different signals to zoom in and out respectively, which State is .called stereo (2ch) mode <br> <br> Bridge mode (bridgemode): bridging mode is to use the amplifier internal two mutual push-pull amplification circuits, thus generating greater output voltage, power amplifier is set to bridged mode, a single .-channel amplifier, the only acceptable way to zoom in, the input signal is output to two-channel power amplifier output is between. <br> Parallel input mode (parallelmode): This means the two-channel power amplifier input signal path for parallel ., only enter one signal to drive two amplifier, two output-output signal same. <br> <br> Frequency range (frequencyrange): indicates that the amplifier you can zoom in on the working frequency, usually 20-20000 Hertz, generally the .data behind a suffix, such as-1 / + 1dB, this represents the frequency range of error or floating range, this value is about small, indicate the frequency range of the frequency response curve more flat. If the amplifier frequency response range to- .3 DB test conditions, the power amplifier sound might not be so flat. <br> <br> Total harmonic distortion (THD): indicates that the power amplifier circuit, due to unavoidable oscillation or other resonance of the second, third harmonic overlay with .the actual input signal, the output of the output signal is not merely with the input signal is exactly the same components, but the harmonic components of signals, these extra out of harmonic composition and actual comparison of the input signal, using a percentage is called .a total harmonic distortion. In General, total harmonic distortion in the vicinity of minimum 1000 cycles per second, so most of the power amplifier that total harmonic distortion is 1000 Hz signal test, but some of the more stringent manufacturers also offer 20-20000 Hz .range total harmonic distortion of data. Total harmonic distortion at 1 per cent, generally ears tell, over 10 percent can clearly audible distortion. The total harmonic distortion of the smaller numeric value, the more pure timbre. General product total harmonic distortion is less than .1% @ 1kHz, but the smaller the number, the higher the quality of that product. <br> <br> Intermodulation distortion (IMD): intermodulation distortion is due to a power amplifier internal transistor work characteristics, the sine wave waveform distortion occurs .. Intermodulation Distortion, directly affects the quality of the sound, tube amplifiers not intermodulation distortion, so generally speaking transistor amplifier sounds feel no tube amplifier so soft and comfortable. General intermodulation distortion values if greater than 0.1%, the power amplifier sound feeling stiff, .astringent, not express exhibition. <br> <br> Common mode rejection ratio (CMRR): common mode rejection is used to measure the common mode signal is inhibition of an amplifier with integrated indicators, detailed definition does not go into details, this parameter .is usually a negative value, such as-60dB, this indicator is also seriously affect the quality of the indicators of the amplifier, the lower the index number, power amplifier, the better the sound quality. <br> <br> Damping coefficient ( .dampingfactor): this is the power amplifier internal resistance and load impedance ratio, damping coefficient = speaker impedance ÷ (amplifier internal resistance + speaker line impedance), high damping factor of power amplifier on speaker unit control capacity enhancement, you can let the cells reaction .closer to the amplifier output signal, but too high damping coefficient will lead to low frequency sound, sound ductility dry and hard. Lower damping coefficient you can get a soft bass, but too low damping coefficient will result in the bass becomes excessively bureaucratic, not .clean. General power amplifier damping coefficient in 200-1000 @ 8 Ohms. Speaker cable quality is not good, wire resistive big also affect amplifier of damping coefficient, built a successful drop control on speaker, voice. <br> <br> Input sensitivity .(inputsensitivity): this is a concept that when voltage amplifier reached full power output, with the input signal voltage, general power amplifier input sensitivity voltage (0dB) to 0.775v 1.5v (+ 6dB), the higher the sensitivity voltage, the lower .the input sensitivity. Some high-quality amplifier, input sensitivity low is because of the negative feedback circuit, so it has lower distortion and wide frequency response and better sound quality. <br> <br> Signal to noise ratio (S / NorSNRorHumandNoise) .: refers to the power amplifier the signal voltage and voltage noise floor, the higher the value, the ratio, indicating that the amplifier's noise even lower. General professional product-to-noise ratio is about 100 decibels, with positive annotation, the higher the .better (some power amplifier using negative callout, value as small as possible). Attenuation of the amplifier's input level gain (off small power amplifier volume knob) will reduce the power amplifier of signal to noise ratio. <br> <br> PassChannel crosstalk .(crosstalk): means that the power amplifier internal two amplifier channel between circuit coupling crosstalk, this index is not a channel's signal to be conspiring to another channel, resulting in another channel not clean sound, channel crosstalk of General-around 60 decibels. This .value is used when a negative value, the callout number, low, representing two zoom channel, the higher the degree of separation between, sound cleaner. <br> <br> Conversion rate (SlewRate).: Measure amplifier response speed is commonly used .voltage conversion rate defined as in 1 microsecond time voltage rise rate, if it is a square wave measurement voltage from trough to Crest the desired time unit is a value V / us, means that the larger the better transient response times, feel the sound speed ., energy and focus. Professional amplifier's conversion rate is generally possible 40V/us above. Conversion rate is lower than 20V/us amplifier sound will feel procrastination and divergence. <br> <br> High-pass filter (highpassfilterorHPF): sound system, .sometimes there are some very low frequency of infrasound (infrasonic) signal inclusion in all audio signals, these infrasound signal ear to hear, but the signal into the speaker, will result in the Bass trumpet produce exciting and cause damage to speakers, all, some .internal amplifier is fitted with infrasound elimination filter, some are on the back panel setup switch when the need for unnecessary 30 Hz or frequency of 40 Hz following, protect the safety of the loudspeaker. <br> <br> Limiter (limiter): this .is the power of protection measures in the amplifier input voltage exceeds the input sensitivity voltage, input signal amplitude, thereby avoiding amplifier because excessive input voltage cut-distortion. Some amplifier with limiter is automatically started, some power amplifier on the back panel installed limiter startup .switches to control the limiters in the start state. <br> <br> Earthing switch (groundleft): amp chassis General and connected to the power transformer shield amplifier box is grounded, but this "land" and "to" signal. When the .power of the grounding-interference, open existing Earth switch let amplifier box touches the ground with hum noise can be reduced, if the power is no ground wire is not connected to interference. <br> <br> <br> <br>.