Background Noise

Discussion in 'Microphones (live or studio)' started by ourkingsransom, Jan 14, 2009.

  1. What would be the ideal setup for a direct setup to minimize distortion with all the outputs in inputs I have avail between all this equipment?

    1. Behringer V-amp
    2. Mobile PreUSB
    3. iBook G4
    4. Boss Pedal Board

    Here's the back of the Vamp for connections

    As well the M-Audio Mobile PRE USB

    I have it currently hooked up as follows:
    -Vamp is connected to the MobilePRE via analong line outputs unblanced L and R
    -Out from Vamp to MobilePRE Ch2/left side of unbalanced Vamp and Ch1/ right side of unblanced Vamp
    -Moniters are hooked up via green 1/4 jack on back of MobilePRE
    -Mobile PRE-USB is obviously in the Usb port

    I have been expereniceing a hum within the moniters before I record and on play back, even when there's no signal I still have this issue. The level of background noise is the same as recorded. Not sure if it's the setup or maybe a connection could be altered to assist. I did as well mix everything down to cd and listened to it on a couple of stereos to make sure it wasnt an isolated case. Also, I tried two different pairs of moniters. It's not over powering the mix but it is suttle enough to negatively effect the production. Once crancked it becomes more appaernt. I really want to clean this up, I do have the behringer vamp grounded as well. I do run a BCB-60 boss pedal board thru the effect loop of the vamp. Even with the guitar pedals out of the effects loop on the vamp i'm still experenicing this. The floorboard consists of a BBE Sonic Maximzer stomp, Boss Noise Suppresor/Gate, Boss TU-2, Boss DD-6 and Boss Flanger.

    The more I research in forums the more I believe that my iBook G4 is contributing to the noise. It is within inchs of my Vamp and Mobile Pre.

    Is XLR connections cleaner than using a 1/8, will I get a better conection since the XLR is grounded? Is this possible with my setup?
    Could I turn down the input to the Mac within the Prefrences for the MobilePRE? Would I have to come in hotter off the front of the Mobile Pre instead?

    Thanks in advance, I just want a starting point so I don't have to waste time tinkering.

  2. GeckoMusic

    GeckoMusic Guest

    Can you clarify your connections? What does this mean?

    "-Vamp is connected to the MobilePRE via analog line outputs unbalanced L and R "

    unbalanced L and R outputs on what? The mobile pre or the Vamp?

    Just list what is connected where. IE Vamp unbalanced Left -> Mobile USB ch2 line input.

    First thought is that it is a ground loop, or dirty power on your MAC book. If you unplug the lap top charger does the hum go away?

    The XLR connection is balanced, so using that instead of the unbalanced connections may help as well. Start with the gain on the mobile pre all the way down, and the volume of the Vamp down. Then bring the Vamp up until you get a good signal.
  3. RemyRAD

    RemyRAD Member

    Sep 26, 2005
    I don't usually recommend that people lift electrical grounds. But with these notebook computers, these direct couples switching power supplies, that are grounded, just create "HUM CITY". SO JUST LIFT THE GROUND ON THE LAPTOP POWER SUPPLY. It's a ground loop. I can use a laptop for audio without running a ground cheater plug.

    Pulling my pins out
    Ms. Remy Ann David
  4. Greener

    Greener Guest

    Just out of interest, if you lift the ground on a laptop power supply, where does the hum go?
    And don't just say away, I want to know where that energy is going, into the battery, into the power supply or into the wall?

    How is it healthy to ever modify electrics if you're not an electrician?

    I've seen people electrocuted because they were messing with mains power... It wasn't fun to watch, and judging from the burns on my friend, not fun to experience.
  5. hueseph

    hueseph Well-Known Member

    Oct 31, 2005
    Vancouver, BC, Canada
    You could just unplugg the laptop when recording. Try using batteries in your effects boxes. You may need to invest in "clean" power for the Boss unit.
  6. Space

    Space Well-Known Member

    Jun 26, 2007
    I don't know "where it goes" either but I do believe that knocking the ground connection off of anything is a poor decision. Using an adapter, maybe, using pliers to rip it off? Not today.
  7. Greener

    Greener Guest

    What's the difference? I can't see a difference between using an adapter and cutting off the wires. Do the adapters have fuses in them?

    I know why there is an earth wire, and I'm happy for it. Most laptop power supplies utilise a computer power supply standard IEC C-13 cable, this is for a Class I electrical product. This product requires an electrically grounded chassis, so if it fails it does so safely and hopefully trips a Safety Switch.
    Only Class II electrical products do not need the ground. They have double insulation and rely on other protections.
  8. Space

    Space Well-Known Member

    Jun 26, 2007
    The difference is that the adapter has a metal eyelet that you can secure with a screw to the O U C H!!!!

    AND I do not like taking things off of cords that look like they belong there.

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