noise floor

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Brett
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2006/05/22 23:48:43 (permalink)

noise floor


I've got an M-Audio FW Solo being fed by an old (classic!) Mackie CR-1604. When I have both the inputs and output to the M-Audio unplugged with just the data cable connected and using bus power; and an audio track in Sonar armed for recording I get -84db of noise, with the Mackie connected and all channels on mute Sonar says it's getting -78db. Is that OK? I'm really concerned that the M-Audio has a SNR of 105db, so where is the extra noise coming from? Environmental? The M-Audio is picking up noise from the enviroment?

Thanks
Brett
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    holderofthehorns
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    RE: noise floor 2006/05/23 00:46:11 (permalink)
    Do you have flourescent lights? Turn them off and recheck in the dark.
    I drop my noise floor 6 db by recording in the dark.

    Guess I need to get some incandescents.

    I read that CRT's generate more EMF noise than LCD/Plasma type monitors.

    Also, balanced cables shield both wires and grounds the shield completely.
    Unbalanced can still be subject to interferance, even though shielded, as the shield is one of the leads.

    Pro studios are anal about their equipment grounding being perfect. It matters.

    Eric Anderson
    HolderOfTheHorns - It's a Viking thing.
    #2
    Jim Roseberry
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    RE: noise floor 2006/05/23 01:31:57 (permalink)
    That 105dB figure is the *average* noise-floor level...

    What you see reported in Sonar is the *peak* noise-floor level.
    Download RMS buddie (free VST plugin)... and you can use that to monitor average noise-floor levels.

    Best Regards,

    Jim Roseberry
    jim@studiocat.com
    www.studiocat.com
    #3
    Brett
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    RE: noise floor 2006/05/24 23:17:50 (permalink)

    Jim, yep I had peak setting. I changed the meters to RMS and the noise is below -90 the limit of Sonar's meters. That's not a problem then.

    Eric, my CRT is the noisest thing in the room! My guitar picks up a lot of noise but my bass is practically unusable.



    Brett

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    holderofthehorns
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    RE: noise floor 2006/05/25 12:51:18 (permalink)
    Cool, sounds like you're on to it.

    I was recently stunned when one of our guys turned out the overhead flourescents.
    I had earphones on, and all of a sudden it got real quiet.

    On - noise.
    Off - quiet. Jeesh. I thought I had all my ducks in a row.
    Then reading your post reminded me of my problem and solution yet to come.

    Right now we record in the dark until we get incandescents installed.

    Wonder what else I've missed?

    Eric Anderson
    HolderOfTheHorns - It's a Viking thing.
    #5
    Brett
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    RE: noise floor 2006/05/25 22:03:22 (permalink)

    Japanese homes are almost entirely flourescent lighting so I was careful about getting incandescents in my loungeroom studio. When I record I also turn off the fridge and of course the aircon. Japanese summer without aircon is taihen (terrible)!

    Brett
    #6
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