No HDMI Sound Under OS X Lion Using A Mini DisplayPort or Thunderbolt Adapter? There's An Easy Fix For That [How-To] | Cult of Mac

No HDMI Sound Under OS X Lion Using A Mini DisplayPort or Thunderbolt Adapter? There’s An Easy Fix For That [How-To]

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I’ve mostly been very happy with my migration to Lion, but I did get bit with one bug after the upgrade: for the life of me, I couldn’t get sound to output through HDMI when using my Kanex Mini DisplayPort to HDMI Adapter. That meant the days of hooking my 11-inch MacBook Air to my 47-inch 1080p HDTV were at an end.

I wasn’t alone. Apple’s support communities are filled with threads from frustrated Lion upgraders who suddenly lost the ability to pump sound through their HTPCs. HDMI sound also stopped working on my girlfriend’s MacBook when she upgraded to Lion. It’s obviously a widespread problem.

Luckily, today I finally figured out how to fix the issue, and it was remarkably simple. Here’s how to get HDMI sound back into Lion.

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The fix is fairly simple, but it might take a few times. What you need to do are flush out your Mac’s PRAM and SMC, resetting them.

Resetting your PRAM is easy:

1) Shut down your Mac totally.

2) Locate (but don’t press) the following keys on your Mac’s keyboard: COmmand, Option, P and R. Put your fingers over them, but don’t press them yet.

3) Turn on your computer.

4) Immediately after turning on your computer, hold down Command+Option+P+R. This must be done before you see the gray boot up screen.

5) Hold down the keys. If you do this correctly, your Mac will restart and you’ll hear the startup sound a second time.

6) Release the keys.

Congrats, your PRAM’s reset! Now let’s reset the SMC for good measure. The instructions on doing this vary from computer to computer, but Apple’s got a great support document that explains how to reset the SMC on any Mac you own.

Once you’ve flushed both the SMC and PRAM, allow your Mac to boot properly. Plug in your Mini DisplayPort or Thunderbolt to HDMI adapter, make sure that HDMI is selected as your Sound output in System Preferences and give your Mac a whirl. Your sound should now hopefully be working through HDMI under OS X Lion. Hoorah!

Using the above steps, I got HDMI sound working on my MacBook Air as well as my girlfriend’s MacBook. How’d it work for you? Let us know in the comments.