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002 rack floor noise

Discussion in 'Recording' started by Smashh, Jul 1, 2014.

  1. Smashh

    Smashh Active Member

    I have a annoying hum in my set up.( a bit like if I put my hand on a live guitar jack humm )
    If I turn my headphones level on the 002 rack over half way it is there ,and at full it is annoying.
    I also have it on my krk5 monitors (which I have set on full volume) ,even if the mute button is on.
    I have a splitter box to amp and auratone speakers, if I switch to them the hum is gone from
    the krks to the auratones . ( just in case its relevant).

    So has anybody else had this prob and is there a process of elimination that I can follow to
    find if there is a fault . transformer positioning ,power plugs etc .

    Now that Im writing this the noise is annoying me more, I think I use to block it out
    and soldier on, but now it is getting in the way of clear recording.
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

    sounds like you have a ground loop. make sure all your equipments ac lines are plugged into the same ac circuit. best way to do this is to have one power conditioner that all equipment is powered by.

    there are other schemes to solve the issue which invole lifting grounds on ac line (not recommended) or on the audio lines ins to your gear.

    from what you discribed it sounds as if your KRK's are plugged into a different circuit than the rest of your gear.

    if this is not the problem be sure to check that the cables that are connecting your KRK's to the interface are of the correct type. they should be shielded rca's , xlr's / trs type.
     
  3. Josh Conley

    Josh Conley Active Member

    ive read before to have power and audio cabling not run next to one another, but only cross one another perpendicularly.
    in a "less than perfect space" i find it impossible to adhere to this rule, and never noticed a difference anyway.

    anyhow, odds are its a ground hum from crappy home wiring like the guys said. i get the same thing if i plug my mackies directly into the wall jack.

    go buy a 100$ furman. all will be set right.
     
  4. Boswell

    Boswell Moderator Distinguished Member

    With these types of problem, you have to do a bit of controlled diagnostic work.

    For example: start with everything unplugged from the 002 rack except the mains input and headphone output. Do you get hum in the headphones? If so, is it affected by the headphone volume control? What happens when you connect the KRK speakers? If you are using unbalanced leads from the 002 to the KRKs, does it make any difference if you use balanced?

    Now do the same set of tests but with the FireWire lead connected between the 002 and your computer. Is there any difference?
     
  5. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    I've heard this too. And yet I've routinely run a 100' A/C line right next to, as in touching, my 100' 16x4 channel snake with no audible effect. I've had more problems trying to power the mix position from a local outlet than from powering it from stage through the extension, and even that was often cured by keeping audio lines properly balanced.
     
  6. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    How are things connected. Specifically, do you have a mix of balanced and unbalanced cabling?
     
  7. Smashh

    Smashh Active Member

    thanks for the replies .

    I have 2 mono shielded wires from 002 rack to a splitter box, made with 2 toggle switches ( 6 pin, one alternates the lft/rght and the other
    switches the ground)
    from there shielded RCA to an amp and speaker 2 core side by side to the aura tones.
    The other way has mic cables to the KRKs.

    I cant afford a furman right now, so tommrw morn Ill try to move the transformers away as far as I can and run the power cables close together.
    Dont know how good it will be,
     
  8. Boswell

    Boswell Moderator Distinguished Member

    I think that indicates that you do have a mix of balanced and unbalanced cabling. One thing you could try is running a pair of TRS jack leads (2 core plus ground) directly from the 002 line outputs to the KRK monitors, not going via the splitter box. If that direct route using balanced cabling results in no hum, it tells you that the hum is coming from the way the splitter configured and its wiring and not the mains supply.
     
  9. Smashh

    Smashh Active Member

    So does that mean I need stereo jack or do I have the screen not attached to anything ?( at the 002 end )

    I will save up and get a furman conditioner , I read an article that says its a must
    for any studio set up .
    Just looked at a few on ebay , cost twice as much here with the different plug ends
    sold seperately too .
     
  10. Boswell

    Boswell Moderator Distinguished Member

    I can't tell which output connectors from the 002 and which input connectors on the KRKs you are using because you haven't responded to the part of the multiple posts that asked you that question. Both these units have alternative methods of connection.

    When using balanced connections, you need a 3-pole connector to deal with the +signal, -signal and ground. It also means you need to use screened cable that has 2 signal conductors inside a screen (which is ground). The common types of 3-pole connector in this industry are the TRS jack (what I think you are calling a "stereo" jack) and the 3-pin XLR.

    It's important that the ground is connected in all cases. For a TRS jack, the ground connects to the sleeve. For an XLR, the ground connects to pin1. The shell of the XLR is not normally connected to pin 1 and the cable screen when wiring a cable to a connector, but the shell may be connected to pin 1 and/or mains earth inside the equipment if the equipment designer requires it to be.
     
  11. Smashh

    Smashh Active Member

    Oh , so I need to get TRS jack for balanced ,I made the wires with jack (2 connections only ).
    Yes I was calling the TRS , stereo jack , learning lots today ,
    thanks for the help :)
     
  12. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Look at this page:

    http://www.rane.com/note110.html

    Specifically, look at wiring diagrams 10 (for active balanced output) and 12 (for transformer or impedance balanced output). Most likely the 002 has active balanced output, so #10 is probably your best bet.

    I would keep it balanced through the switch box and build a #10 cable to go from the box to the amp powering the Auratones. That means all TRS on the box and a four pole double throw switch. Alternatively you could build the #10 wiring right into the box and have RCA out for the Auratone amp.
     

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