pro tools 7.4.2 "data style" noise. any experience?

Discussion in 'Digital Audio' started by dark knight, Nov 5, 2008.

  1. dark knight macrumors regular

    Oct 28, 2008
    sorry for the very long post, i put this question to digidesign and am waiting to hear back.

    i have a brand new unibody macbook pro 2.53 with a brand new mbox 2 and le 7.4.2 on leopard. when the mbox is disconnected the audio out of my mac is nice and quiet. i connect the mbox and the macs own audio out becomes noisy with a "hissy data type" noise. i say data because i kind of fluctuates and you can pretty much hear the mbox working. the mbox's own audio outs are nice and clean.

    now the next oddity about this is that this only happens when both the mbox and the macs audio outs are connected to the same amplifier (different, switched channels). so what happens is this.

    the amp is connected (via analogue) to the macbooks headphone out, all nice and clean. plug the mbox in and the macs headphone out becomes noisy.

    if i switch channels on the amp over to the mbox, its all nice and clean.

    if, while i am listening to the noise on the macs headphone output, i disconnect the monitor out jacks on the back of the mbox - the noise goes away.

    so to summarize. you need to have the mbox plugged into usb and hooked up to the amp in order to make the macs headphone jack noisy.

    very odd. i know your going to say call apple, which i may have to do, but i know they are going to say call digidesign as this only happens when using mbox 2.

    to me it does sound like an earthing problem but the problem remains when the notebook is on battery power. and if it was just a case of the mbox generally giving off interference and making another channel noisy then the problem would be consistent (and it isnt as it goes away if you disconnect the audio out jacks from the mbox, and im not even listening to that signal!). the problem also comes and goes when connecting and disconnecting the headphone jack on the front of the mbox.

    lastly, i have just noticed that this same noise is audible on the mbox outs but at a greatly reduced volume and only expected. its the louder version that ends up on the mac outs that puzzles me.

    sorry for the long question.

    i include a short sound clip. thanks, ben
  2. thevibesman macrumors regular

    Oct 26, 2007
    Let me reread this when I am not so tired, but just because the laptop is on battery does not necessarily rule out earthing problem as your whole system is still connected to earth through the amp.

    Also, looks like the clip didn't post.

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