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Digi 002 phantom power.

Discussion in 'Recording' started by rush_boy2112, Jun 12, 2007.

  1. rush_boy2112

    rush_boy2112 Guest

    Does anyone know if the digi 002's line mic inputs have phantom power? and what mics require phantom power?
     
  2. BobRogers

    BobRogers Well-Known Member

    The Digi 002R has phantom power on channels 1-4 (the ones with the xlr inputs and mic preamps) Phantom works in pairs (1-2 on/off and 3-4 on/off).
     
  3. sheet

    sheet Well-Known Member

    Tutorial from the Rane Pro Audio Reference

    condenser microphone [Also called capacitor microphone but more properly, the correct name is electrostatic microphone.] A microphone design where a condenser (the original name for capacitor) is created by stretching a thin diaphragm in front of a metal disc (the backplate). By positioning the two surfaces very close together an electrical capacitor is created whose capacitance varies as a function of sound pressure. Any change in sound pressure causes the diaphragm to move, which changes the distance between the two surfaces. If the capacitor is first given an electrical charge (polarized) then this movement changes the capacitance, and if the charge is fixed, then the backplate voltage varies proportionally to the sound pressure. In order to create the fixed charge, condenser microphones require external voltage (polarizing voltage) to operate. This is normally supplied in the form of phantom power from the microphone preamp or the mixing console.

    phantom power Invented by Georg Neumann in 1966, the term given to the standardized scheme of providing power supply voltage to certain microphones using the same two lines as the balanced audio path. The international standard is IEC 60268-15, derived from the original German standard DIN 45 596. It specifies three DC voltage levels of 48 volts, 24 volts and 12 volts, delivered through 6.8k ohms, 1.2k ohms, and 680 ohms matched resistors respectively, capable of delivering 10-15 mA. The design calls for both signal conductors to have the same DC potential. This allows the use of microphone connections either for microphones without built-in preamps, such as dynamic types, or for microphones with built-in preamps such as condenser and electret types.
    Why 48 volts is an interesting question. The answer is three-fold: 1) 48 volts is an exact multiple of the 1.5 volt battery cell; 2) 48 volts has been the telephone communication standard since before 1900; and 3) both of these combine to give the background to the explanation direct from Jürgen Breitlow and Stephen Peus at Neumann:
    "In 1966, a Neumann engineer presented the latest developments in the field of studio microphones at Norwegian Radio and Television in Oslo. The first transistorized condenser microphones were shown at that time, together with the well-known tube microphones.
    For compatibility reasons, Norwegian Radio wanted the transistor microphones to be supplied with a phantom powering system. Due to the limited amount of daylight available there in winter, an auxiliary lighting system was installed in the studios — fed from a central 48 V supply. This voltage would also be used for phantom powering the microphones.
    So the 48 volt phantom powering system, which was later standardized in DIN 45 596, came into existence."

    Phantom Power Mini-tutorial: Much confusion surrounds phantom power. This is an area where you need to make informed decisions: Is it provided? Do you need it? Is it the correct voltage, and does it source enough current for your microphone? There is a huge myth circulating that microphones sound better running from 48 volts, as opposed to, say, 12 volts, or that you can increase the dynamic range of a microphone by using higher phantom power. For the overwhelming majority of microphones both of these beliefs are false. Most condenser microphones require phantom power in the range of 12-48 VDC, with many extending the range to 9-52 VDC, leaving only a very few that actually require just 48 VDC. The reason is that internally most designs use some form of current source to drive a low voltage zener (usually 5 volts; sometimes higher) which determines the polarization voltage and powers the electronics. The significance is that neither runs off the raw phantom power, they both are powered from a fixed and regulated low voltage source inside the mic. Increasing the phantom power voltage is never seen by the microphone element or electronics, it only increases the voltage across the current source. But there are exceptions, so check the manufacturer, and don't make assumptions based on hearsay. From the RaneNote Selecting Mic Preamps.
     

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