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microphone bias not working

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Stan VA7NF
Stan VA7NF Member ✭✭✭
edited November 2019 in SmartSDR for Windows
6700 V3.1.8 using rear balanced input with XLR or phono input does not supply the microphone bias.  Mic and XLR cables work fine with my own preamp supplying the bias.  I have measured voltages between all XLR leads with no change between BIAS ON or OFF

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  • Brian Denley KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited November 2019
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    What is the mic?  Make sure there isn’t a blocking cap in the circuit.
  • Craig_KØCF
    Craig_KØCF Member ✭✭✭
    edited October 2019
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    From the Flex-6000 Hardware Manual:
    "7.10.2 MIC vs. LINE Use
    The balanced input can be used as a microphone level or a line level audio input. The microphone level is suitable for a dynamic microphone. The balanced input does not have any DC bias capability. If your microphone requires bias power (5VDC) or phantom power (48VDC), an external power supply is required."

    If you want to use an electret microphone, you have to use the front-panel mic connector, or as noted above, use an external bias source.


  • Stan VA7NF
    Stan VA7NF Member ✭✭✭
    edited October 2019
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    Thanks Craig for the reference.  Perhaps twice a year I use a mic and this year it was Scouting Jamboree on the air.  I was sure that over the past 5 years I have used a balanced mic requiring phantom power, perhaps old age was the problem.  
    Brian - The mic is a Behringer C-1 which works very well when passed through a "tube" preamp.  Previous mics that have worked were a Blue Yeti and most often a Sennheiser headset which I know does NOT need phantom power.
    Thanks.
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited October 2019
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    Stan Can you measure with a multimeter to see if there is voltage on the mic connector? Mike.
  • Stan VA7NF
    Stan VA7NF Member ✭✭✭
    edited October 2019
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    Mike,
    Original note - Measured the voltages on all leads, as Craig referenced, there is no phantom voltage on the balanced XLR rear port.  Disappointing as a high percentage of XLR mics use phantom power and BIAS set on was just expected to apply to the BAL port.
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited October 2019
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    Hi Stan

    My fault, sorry, I missed that and I should have known better.  Even worse, I actually knew that.

    Thanks for calling me out on it.

    Mike

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