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Thread: Compression and noise floor question

  1. #1
    Member shorter126's Avatar
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    Compression and noise floor question

    Hi all

    I've been trying to deal with an issue in Adobe audition that causes a great deal of frustration for me. When i record my podcast I have no "noise" in the background , thanks to a noise gate on my compressor and a ground loop isolator.

    However during post production, when i normalize and use the multi-band compressor tool , hissing is introduced. I hear a lot of podcasts out there where this hiss is not present. Am I doing something wrong ?

    Thanks,

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    Moderator / IAIB Pro Broadcaster mcphillips's Avatar
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    A compressor reduces audio dynamics and, therefore, reduces your signal-to-noise ratio. Think about it like this. If your compressor reduces your overall volume by 10 dB on a peak, when the compressor "relaxes", or does not attenuate, it essentially turns UP your volume by 10 dB. So, if the normal noise floor on your audio is -45 dB, after running the audio through a compressor set for 10 dB compression, your noise floor is only -35 dB. That's one possibility.

    Why don't you post a before and an after clip of your audio so that we can try to hear what you're doing? Compressors are difficult to set just right. Most people set them incorrectly. There could be something else going on.
    Please direct all questions for me to the forum so that all can benefit.

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    Administrator andrewzarian's Avatar
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    I know Mike would have an answer for this

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    Member shorter126's Avatar
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    My last episode of tektalk5 was recorded and processed with Adobe Audition. You can hear it here.

    A sound file with no compression is attachedUntitled Session 1_mixdown.zip

    Thanks a bunch !

  5. #5
    Moderator / IAIB Pro Broadcaster mcphillips's Avatar
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    I apologize if you've posted this information elsewhere already, but what mic and mic preamp are you using? How is your preamp or mixer connected to the computer? What sound card are you using? How far away from the mic are you talking? What sort of acoustical treatment do you have in your room?

    Something doesn't sound exactly right about your raw file, and I can't put my finger on it. If you're using Audition to correct a deficiency, you're also amplifying the deficiency.
    Please direct all questions for me to the forum so that all can benefit.

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    Member shorter126's Avatar
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    Quote Originally Posted by mcphillips View Post
    I apologize if you've posted this information elsewhere already, but what mic and mic preamp are you using? How is your preamp or mixer connected to the computer? What sound card are you using? How far away from the mic are you talking? What sort of acoustical treatment do you have in your room?

    Something doesn't sound exactly right about your raw file, and I can't put my finger on it. If you're using Audition to correct a deficiency, you're also amplifying the deficiency.
    Hi,

    The equpment i use is as follows
    Heil PR40 microphone,
    Mackie Pro FX 8 mixer,
    MDX4600 Compressor Limiter Gate

    I also use an external USB sound card which has a ground loop isolator attached. The mixer is attached to the sound card through the line out port.

    I am fairly close to to mic but not speaking into it directly.

    My studio has nothing more than heavy curtains in it.

    Thanks !
    Last edited by shorter126; 09-19-2012 at 01:42 AM.

  7. #7
    Moderator / IAIB Pro Broadcaster mcphillips's Avatar
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    Are you speaking into the side of the PR40 instead of into the end? Your voice sounds off-axis.
    Please direct all questions for me to the forum so that all can benefit.

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    Member shorter126's Avatar
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    Quote Originally Posted by mcphillips View Post
    Are you speaking into the side of the PR40 instead of into the end? Your voice sounds off-axis.
    I do speak more into the side rather than full on !

  9. #9
    Moderator / IAIB Pro Broadcaster mcphillips's Avatar
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    You must speak directly into the END of the PR40. It looks like a side-address mic, like the Audio-Technica AT2020, but if you talk into the side, you are "off-axis", and the sound is terrible. The optimum distances is 3 to 4 inches, based on your room acoustics.
    Please direct all questions for me to the forum so that all can benefit.

  10. #10
    Member shorter126's Avatar
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    Quote Originally Posted by mcphillips View Post
    You must speak directly into the END of the PR40. It looks like a side-address mic, like the Audio-Technica AT2020, but if you talk into the side, you are "off-axis", and the sound is terrible. The optimum distances is 3 to 4 inches, based on your room acoustics.
    Thanks for that advice. I used to see others speaking side ways to the mic and assumed this was okay. Is there any way I can reduce the "noise" afeter I use the compressor in Audition. I don't really want to use their noise reduction !

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