I am curious about how Apple's computer DACs are implemented, especially on computers like MacBooks and iMacs. I have been trying to figure out if the 3.5mm output on Apple devices (specifically a MacBook Pro, for me) is controlled by the system volume level through an analog section after the actual DAC, or is it reducing the volume digitally before the DAC?

I can't seem to find any good info about it. Does anyone know?

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    The distinction is only really of any importance in mission-critical audio production. The output from a computer's built-in circuitry would really not be used for anything mission-critical. I think, honestly, the answer is 'it doesn't matter'. – Tetsujin Mar 24 '18 at 19:08
  • I have edited my question. I am genuinely curious about electronics and how this is implemented. If I were overly concerned about "bit-perfect representations" and such, I would not use streaming music services or the internal DAC. I just wonder how Apple makes these things. – Tom Ato Mar 26 '18 at 1:26

The volume control on a computer (specifically, your MacBook) is usually handled by your audio API, which on Mac OS X is CoreAudio. All computers these days will act like this, but I seem to recall one Toshiba laptop of my parents’ running Windows 98 with a physical dial on the side for audio. Obviously this is not practical today due to modern laptops getting thinner and digital audio outputs such as SPDIF and HDMI audio. I might be rambling a bit, but I hope this answers your question.

  • So then the volume control is in fact acting entirely in the digital domain? – Tom Ato Mar 26 '18 at 14:02
  • @TomAto Exactly. It helps streamline the volume across the outputs/system and means that other programs can control the volume, such as iTunes/Spotify. Also, have you ever noticed the Apple Earpods w/mic have volume control buttons? – Srevilo Mar 27 '18 at 4:22
  • They send specific signals thru the mic ring and the computer recognises it. – Srevilo Mar 27 '18 at 4:23

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