MacBook Pro Sound Card Specs

Discussion in 'General Electronics Chat' started by blah2222, Aug 12, 2014.

  1. blah2222

    Thread Starter Well-Known Member

    May 3, 2010

    I have been working on a guitar preamp interface for recording on my MacBook Pro. It is just a simple MPF102 amplifier powered via 9V battery with a 4-section 3.5mm plug so that I can listen through headphones while playing.

    Under ~500uA load the microphone input becomes recognized by the notebook and activates a 2V phantom source with ~2.5 kOhm of resistance.

    I have seen devices of similar function completely sourced by the notebook, but at only 2V, it would barely even turn on these JFETs. Though an extinct J201 might just work...

    All is fine and dandy and the circuit works, but I was wondering if this is a standard across the product line for DC level and resistance?

    Comparably, connecting as a line-in device shows no DC phantom power.

    I can't seem to find any specs other than these, which are very limited.

    My Lenovo T430 sources 3.75V @ ~2 kOhm, which would be more room to play with for a JFET preamp.
    Last edited: Aug 12, 2014