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Improve OSX internal audio output quality

Saturday August 13 2011

For years something has been nagging me on my machine. When playing back audio at low levels from the internal audio device, for instance on headphones, I could distinctly hear a lack of dithering on the volume control. Especially noticeable on fade-outs, where all these nice high aliasing frequencies were introduced.

I couldn’t believe that Apple, a company focused on details, would have such an oversight in their audio drivers. Volume control without dithering? That’s crazy. But it was there, really.

Lo and behold, one day I check into Audio MIDI Setup and find out that my audio device is set to 2ch-24bit Integer, and that there is also a setting for 32bit Float. Why is it there, and does it make a difference? It turns out, that at 32bit Float the sound is dithered nicely when lowering the volume. Hurray!

But why is it set at this non-native setting at my machine? I guess it’s because over the years I never reinstalled OS X when getting a new machine. I always used the migration tools (working surprisingly well I might add), and never did a clean install. It must have taken this setting with me from the days of my old PowerBook, Core2Duo Alu MacBook Pro, into this Unibody one. Different sound interface, same setting, different sound.

Another mystery solved. Hope this post helps other people, anal about sound as me!


RxG @ Friday April 4 2014 02:48
Nice ! :)
Kon @ Tuesday January 20 2015 05:13
I started with a unibody 2011 MBP but only recently discovered this setting. I dont think its the default even on a fresh install (at least not when your post was written)

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