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All condenser microphones need power in order to polarize the capsule, which produces the initial signal, and to power the microphone's preamp, which takes that small signal and amplifies it.


While many condenser microphones will get enough power through standard 48-volt phantom power, some microphones, such as tube microphones, require even more power. For these microphones, a dedicated, external power supply is necessary. 

Most tube microphones and all MXL tube microphones ship with their own external power supply. (Examples: Revelation II, V69M)


The two most common ways condenser microphones and the way in which they are powered are listed below.

  • Regular Condenser Microphones- (external power supply usually not needed)
    1. Powered by standard 48v Phantom Power
    2. 3-pin XLR connection 
      • carries audio and power on the same signal lines
  • Tube Microphones(usually requires external power supply)
    1. External power supply unit
      • Provides enough power to fuel the tube, as well as internal circuitry
      • Could provide up to 250v or more
      • Includes regular 3-pin XLR output to connect to mixer or preamp
      • Only use the dedicated power supply that comes with your microphone. They are not interchangeable.
    2. 7-pin XLR connection
      • Connects the microphone to the power supply unit
      • Carries audio and power on separate lines, powering multiple elements of the tube
      • Recommended to use the 7-pin XLR your microphone comes with, however, any standard 7-pin XLR will work

Important Reminders:

  1. Each dedicated power supply unit is meant to power just that one microphone's tube and specific circuitry. 
    • Mixing PSU's could damage your microphone.
  2. Power tubes need time to warm up in order to reach full power. 
    • Be sure to allow your microphone 5-10 minutes to power up before using.
  3. Connect your 7-pin XLR to your microphone and power supply unit BEFORE powering on. 
    • Connecting the 7-pin XLR to your microphone while the power supply unit is on can cause a surge of energy that can damage your microphone.

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