MBP Mic-In vs Line-In

Discussion in 'MacBook Pro' started by chewbacalips, May 21, 2011.

  1. chewbacalips macrumors newbie

    Joined:
    Feb 1, 2011
    #1
    I have a 13" MBP (December, 2010). It only has one audio port, but can function as two; I can change it to function as audio-output to an audio-input via my system preferences. However, how can I find technical specs behind the audio-input function? Specifically, is this a Mic-In or a Line-In, or can it function as both?

    I want to record audio from various sources, such as a PA sound board system and cassette decks. Both, the PA sound board and the cassette deck can plug right into my audio port via a 1/8" audio jack.

    But, if I remember correctly, there is a significant (and dangerous) difference between a Mic-In and a Line-In. Because Microphones produce a very weak signal output, a Mic-In jack is directly connected to a 60dB pre-amp. In contrast, Line-In sources are usually strong, and thus do not need the pre-amp. This is important because connecting a Line-Out (from my PA system or cassette deck) to my Mic-In will amplify my already-strong electronic signal by 60dB, and can thus cause my system to malfunction permanently by overloading the circuitry. Microphones need this 60dB to obtain a proper recording signal, but Line-Out sources do not. Thus, a Mic-Out should be connected to a Mic-In, and a Line-Out should be connected to a Line-In.

    I can buy an external USB sound card with proper input capabilities, but these things are around $30-$50 and a hassle to carry around. I'd really rather plug right into my audio jack. So, what's the deal with the MBP audio-input, is this a Line-In or a Mic-In?
     
  2. DustinT macrumors 68000

    DustinT

    Joined:
    Feb 26, 2011
    #3
    you've got it right. Its a line-in jack so you need a preamp or a USB microphone input. For the kind of work you are talking about doing the investment in a simple mixer would do you a lot of good. There are a variety that cost $60-100 with up to 8 channels of inputs, basic mixing, monitoring and a few other features. Pretty simple way to go. Check BH for a few and I'm sure there's others out there I don't know about.
     
  3. chewbacalips thread starter macrumors newbie

    Joined:
    Feb 1, 2011
    #4
    Excellent, LINE-IN is exactly what I need! I'm going to test it to see if it works as good as the external USB sound card.

    A new question: In Windows XP (via Bootcamp on MBP), how do you change the audio port from output-to-input?
     

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