level 7
那是信号接口吧;
2009年03月28日 12点03分
level 7
歪歪雪人
楼主
There's only one type of Phantom powering, and that's Phantom powering. Phantom powering deltais are covered by DIN spec 45596. Initially, it was specificed as 48 volts (P48) provided thru 6.8k resistors. The precise value of the resistors is not too critical, but the two resistors must be matched within 0.4% for good performance. There are now defined systems at 24 and 12 volts (P24 and P12), but those are more rare than traditional 48V feed. Those lower voltage systems use lower resistance values for phantom powering. Most modern condensor microphones will work off a wide range of phantom power voltages. The 48V (+10%..-20%) phantom power is the de-facto microphone powering method supported by practically all marjor sound mixers. There are some audio equipment that use lower phantom power voltages. The most commonly used lower voltage is 15V through 680 ohm resistors (used for example on portable sound systems). Some wireless microphone systems can use even lower voltages, for example low power 5V or 9V supply.
Phantom powering is now the most common microphone powering methid due to it being safe if a dynamic (moving coil or ribbon) microphone is accidently or purposefully plugged into a powered microphone channel. The only hazard is that in case of a shorted microphone cable, or certain old microphones having a grounded center tap output, current can flow through the microphone, damaging it. It's a good idea anway to check cables regularly to see that there are no shorts between any of the pins, and the few ribbon or dynamic microphones with any circuit connection to ground can be identified and not used with phantom power.
The name for phantom power comes from telecommunications: A phantom line is a configuration where a telegraph signal is imposed on a balanced voice pair by using the ground return. This same method was also suitable for powering microphones in studios so it was used also there.
2009年03月28日 12点03分
3
Phantom powering is now the most common microphone powering methid due to it being safe if a dynamic (moving coil or ribbon) microphone is accidently or purposefully plugged into a powered microphone channel. The only hazard is that in case of a shorted microphone cable, or certain old microphones having a grounded center tap output, current can flow through the microphone, damaging it. It's a good idea anway to check cables regularly to see that there are no shorts between any of the pins, and the few ribbon or dynamic microphones with any circuit connection to ground can be identified and not used with phantom power.
The name for phantom power comes from telecommunications: A phantom line is a configuration where a telegraph signal is imposed on a balanced voice pair by using the ground return. This same method was also suitable for powering microphones in studios so it was used also there.
