录音 / 混音

jamfer1314 发表于 17-6-5 04:39
哎呀都这么多天了，也没个大师搭理下~

Electrical characteristics
电气特性

Electrical characteristics of dynamic loudspeakers may be readily applied to headphones, because most headphones are small dynamic loudspeakers.
扬声器的电气特性可以直接应用在耳机上，因为大多数耳机都是小动态扬声器。

Impedance
阻抗

Headphones are available with low or high impedance (typically measured at 1 kHz). Low-impedance headphones are in the range 16 to 32 ohms and high-impedance headphones are about 100-600 ohms. As the impedance of a pair of headphones increases, more voltage (at a given current) is required to drive it, and the loudness of the headphones for a given voltage decreases. In recent years, impedance of newer headphones has generally decreased to accommodate lower voltages available on battery powered CMOS-based portable electronics. This has resulted in headphones that can be more efficiently driven by battery-powered electronics. Consequently, newer amplifiers are based on designs with relatively low output impedance.
耳机有低阻抗与高阻抗（通常在 1kHz下测量）。低阻抗耳机为16-32Ω，高阻抗为100-600Ω。在一副耳机阻抗增加时，需要更高的电压（在给定电流下）来驱动，在给定电压下的响度减少。近年来，为了适应电池驱动的机遇CMOS的便携电子产品，新款耳机的阻抗普遍降低。这使得耳机能够更有效的被电池驱动的电子产品驱动。因此，新款的放大器也相对采用低阻抗的设计。

The impedance of headphones is of concern because of the output limitations of amplifiers. A modern pair of headphones is driven by an amplifier, with lower impedance headphones presenting a larger load. Amplifiers are not ideal; they also have some output impedance that limits the amount of power they can provide. In order to ensure an even frequency response, adequate damping factor, and undistorted sound, an amplifier should have an output impedance less than 1/8 that of the headphones it is driving (and ideally, as low as possible). If output impedance is large compared to the impedance of the headphones, significantly higher distortion will be present.[9] Therefore, lower impedance headphones will tend to be louder and more efficient, but will also demand a more capable amplifier. Higher impedance headphones will be more tolerant of amplifier limitations, but will produce less volume for a given output level.
由于放大器的输出限制，耳机的阻抗受到关注。现代的一副耳机是由一个放大器驱动的，低阻抗耳机呈现出更大的负载。放大器并不是理想的；它们也有输出阻抗，限制了它们所能提供的功率。 为了保证平坦的频率响应，适当的阻尼因数，和不失真的声音，放大器的输出阻抗因小于它驱动耳机的1/8（理想状态下，尽可能低）。如果输出阻抗比耳机阻抗大，将出现显著失真。[9]因此，低阻抗耳机将会更响并且更高效，但是同时也需要更强大的放大器。高阻抗耳机容忍放大器限制的能力更强，但是给定输出电平下输出的音量低。

Historically, many headphones had relatively high impedance, often over 500 ohms in order to operate well with high-impedance tube amplifiers. In contrast, modern transistor amplifiers can have very low output impedance, enabling lower-impedance headphones. Unfortunately, this means that older audio amplifiers or stereos often produce poor-quality output on some modern, low-impedance headphones. In this case, an external headphone amplifier may be beneficial.
从历史上来看，许多耳机都有相对较高的阻抗，往往超过500欧姆，以便适应在高阻抗的管放大器下工作。相比之下，现代晶体管放大器的输出阻抗非常低，使得低阻抗耳机成为可能。不幸的是，这意味着老式放大器或音响在现代低阻抗耳机上往往产生低质量的输出。在这种情况下，外部耳机放大器可能是有益的。

Sensitivity[edit]
灵敏度
Sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound. It thus indicates how loud the headphones will be for a given electrical drive level. It can be measured in decibels of sound pressure level per milliwatt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V).[10] Unfortunately, both definitions are widely used, often interchangeably. As the output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's Law:
灵敏度是衡量耳机传入的电信号转换到可听声音效率的参数。它表明耳机在给定的电驱动电平上会有多响。它的单位是分贝（SPL）每毫瓦或分贝（SPL）每伏特[ 10 ]不幸的是，两者的定义是广泛的，经常交替使用。由于耳机放大器的输出电压（但不是电源）在大多数普通耳机中基本上是恒定的，所以如果使用欧姆定律转换成 dB/V通常更有用：



Alternatively, online calculators can be used.[11][12] Once the sensitivity per volt is known, the maximum volume for a pair of headphones can be easily calculated from the maximum amplifier output voltage. For example, for a headphone with a sensitivity of 100 dB (SPL)/V, an amplifier with an output of 1 root-mean-square (RMS) voltage will produce a maximum volume of 100 dB.
或者，可以使用在线计算器转换。[ 11 ] [ 12 ]一旦每伏特的灵敏度已知，一对耳机的最大音量可以很容易地由最大输出电压计算出。例如，对于一个灵敏度为100dB (SPL)/V 的耳机，一个输出1RMS（rms）电压的放大器将产生100dB的最大音量。

Pairing high sensitivity headphones with power amplifiers can produce dangerously high volumes and damage headphones. The maximum sound pressure level is a matter of preference, with some sources recommending no higher than 110 to 120 dB. In contrast, the American Occupational Safety and Health Administration recommends an average SPL of no more than 85 dB(A) to avoid long-term hearing loss, while the European Union standard EN 50332-1:2013 recommends that volumes above 85 dB(A) include a warning, with an absolute maximum volume (defined using 40–4000 Hz noise) of no more than 100 dB to avoid accidental hearing damage.[13] Using this standard, headphones with sensitivities of 90, 100 and 110 dB (SPL)/V should be driven by an amplifier capable of no more than 3.162, 1.0 and 0.3162 RMS volts at maximum volume setting, respectively to reduce the risk of hearing damage.
一对高灵敏度的耳机和放大器会产生危险的高音量并损坏耳机。最大声压级是一个应优先考虑的问题，一些来源推荐不超过100-120 分贝。相反的是，美国职业安全卫生管理局 推荐平均SPL不超过85 dB(A)以避免长期听力损伤，而欧盟标准 EN 50332-1:2013 推荐超过且包括 85 dB(A)就应警示，绝对最大音量（定义为40-4000 Hz 噪音）不超过100 dB以避免听力损伤。[13]通过这个标准，灵敏度为90，100和110 dB (SPL)/V的耳机，分别应由最大音量设置不超过3.162，1.0和0.3162 RMS 的放大器驱动，以减少听力损伤的风险。

The sensitivity of headphones is usually between about 80 and 125 dB/mW and usually measured at 1 kHz.[14]
耳机的灵敏度通常在80到125dB/mW之间，在1 kHz下测量。[14]