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Condenser Mic pre-amp and smart SDR integration

Playing around with using a Neumann 102 condenser with 6400. Not sure about the correct signal path. Running the 102 into a PreSonus Tube PreV2, fuel the mic with 48v phantom, send the signal via XLR out to TRS mic input on 6400 back panel. My question is, is there a potential conflict between the outboard mic pre, and the mic gain in smart SDR? I think maybe. I have set the radio mic gain to 0, and use the outboard mic pre to gain set the mic. Then I use the onboard 8 band to shape the audio to my liking. For giggles I have a wee bit of tube drive just to round the tone via the tube pre. For those of you in the know does this sound correct to you? Or put another way what is the correct way to use an outboard mic pre with a condenser on a Flex 6400 with only the mic input. Again, not sure if I have this right. Thanks all for your help.


  • John KB4DU
    John KB4DU Member ✭✭✭✭

    This should be ok. The 102 needs the 48v from the pre, since the flex can’t provide that. I would keep the gain on the pre pretty low to not overdrive the mic level input on the flex. Also, the audio level on the flex is measured before the eq so be cautious with eq, especially 4K and higher. Easy to exceed the tx bandwidth and generate distortion artifacts.

  • rbrossetto
    rbrossetto Member ✭✭
    Many thanks for the comment. With the radio gain set to zero it’s the mic pre doing the work. I am conscious of not driving the vu on the pre into the red, and keeping the metering on the flex at 0. That said this mic does seem to like having gain in the 2 and 4K. For my voice not so much 1k as I start to sound too nasal. I was not sure sure I could use the mic input. It works but I don’t want to hurt anything. The accessory input, not sure how I would do that, xlr to 9 pin? Seems to work and getting good reports. I have used duplex to listen but not sure I’m capturing my audio all that well.

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