Remote powering implies that the power equipment is not local but some distance away. This article is remote powering audio edition. It can be seen a continuation of my earlier Remote powering over communications cabling posting series.
Microphone: Phantom power
Microphone: Digital microphones
Digital microphones are another story. Digital microphones complying with the AES 42 standard may be provided with phantom power at 10 volts, impressed on both audio leads and ground (up to 250 mA ). USB microphones are powered with normal USB power (5V 500mA).
Speaker level signals are post amplification signals that drive passive loudspeakers. The signal is AC signal (typically 20Hz-20kHz)that has same waveform and the audio signal had. The signal level and current depends on the power being fed to the speaker element. For example, 1,000 watts feeding an 8-ohm load would require an 89.4 volt level (with a complementary current of 11.2 amps). There is limited cable length and longer the cable needs to be the thicker it needs to be to avid too much resistance causing issues with speaker performance.
There is also 70 volt speaker system in use. 70 volt systems are generally used in commercial applications where many speakers needs to be run from one amplifier. It is also called high impedence speaker system. It allows using long cable runs of relatively small gauge (usually 20-24 gauge) do not significantly affect the output You would want to use this type of system if you plan on powering say 10 speakers with one amplifier(one 100W amplifier can power ten 10W speakers). A 70 volt system is used in restaurants, small bars, department stores etc. 70 volt is common in the US, but in other countries there other high impedance system, including 25 and 100 volt.
USB (abbreviation of Universal Serial Bus), is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication, and power supply between personal computers and their peripheral devices.
The Universal Serial Bus connection is commonplace and allows you to connect and record instruments, microphones, and audio inputs to a computer. USB interfaces can be mains or bus powered depending on the model.
The USB 2.0 max current is 0.5A for normal USB use, while USB 3.0 is 0.9A. Higher currents can use used for charging applications using normal USB connectors (typically up to around 2A) and with USB type C connector (up to 20V 5A).
Intercom is a private telecommunciation system that allows typically two or more locations to communicate with each other like telephone does. Many productions which needs co-operation of more than a few people need special intercoms that cover many users. Intercom systems used in TV and stage productions are usually headset type intercoms connected to one line using party line arrangement.
The most commonly used intercom system I have seen in use is Clear-Com party line system that uses 3 pin XLR connectors for the line. It uses the following pin-out on XLR conector: Pin 1: Common; Pin 2: PL Power (+28VDC); Pin 3: Line (Audio). The power supply can typically supply power maximum up to 2A.