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Cable lengths and phase errors

Discussion in 'Studio Techniques' started by Lauren2010, Mar 31, 2011.

  1. Lauren2010

    Lauren2010 Member

    Will the following setup cause phase errors if I track an acoustic guitar (or some other source) with two mics:

    (all cables are balanced xlr)

    signal path 1:


    signal path 2:

    AT4050->cable2(6ft)->preamp(grace m101)->cable3(3ft)->apogeeDuetLineInput2

    Assume the mics are an exact same distance from the performance.

    Even if I replaced cable1 with a 9ft cable (if I can get one), would I still have possible phase errors because I have a preamp in signal path 2 but not signal path 1?

    In other words, MUST I buy another preamp (and must it be the same brand/model) and have all the cable lengths match in order to avoid phase errors?

  3. Markdvc

    Markdvc Administrator Staff Member

    There are various values as to the speed at which a signals travels through a cable. Typical figures are around two thirds the speed of light, i.e. around 200,000 kilometers/second. Compare this with the speed of sound of around 343 meters/second and it will become apparent that the slightest difference in placement between two microphones will have a much greater effect on potential signal differences than even substantial differences in cable length.

    The short version is - don't worry about it, it won't be of relevance :)

    kind regards

  4. Lauren2010

    Lauren2010 Member

    Brilliant ! Love the science there.

    Many thanks
  5. georgelegeriii

    georgelegeriii Senior member

    Without getting scientific, as long as the mic's are in phase, you are good to go.
  6. Eli

    Eli Senior member

    Also, without getting too scientific here either - don't worry about. If you record you tracks and find that there are phase problems, just flip the phase on one of the tracks. You can easily do it with the Gain plug-in.

    In fact, I'd suggest toggling the phase invert button on/off back and forth a few times as the tracks are playing in order to verify if it sounds better with the phase inverted on one of the tracks or not.
  7. bambony

    bambony Administrator Staff Member

    The biggest phase issues will be as a result of mic placement. For one you can't see the SM7 capsule to place it equidistant with the 4050 from the source. Use your ears switching phase in and out until it sounds as good as you can get! ISO headphones can work well here too.

  8. michaelo

    michaelo LUG Emeritus

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