I recently replaced the internal hdd inside my macbook pro mid 2012 with a ssd. Now it seems that the system chime (the "boong" that goes off when i turn it on) only plays through the right speaker. Within the OS sound comes out of both speakers.

I have tried both a NVRAM reset and a smc reset.

What could be the issue?

  • You hit the speaker cable when disassembling and assembling?
    – Rob
    May 6, 2014 at 6:36
  • 1
    Either you bumped the speaker cable or your shorted the MLB... Take to a AASP or Apple Store and let them test it out.
    – Andrew U.
    May 6, 2014 at 10:59
  • The speaker works fine inside the OS. (Confirmed via changing the left and right balance in the system preferences) May 6, 2014 at 14:09
  • 1
    @Rob How can it be the Cable if it works normal after the boot?
    – Ruskes
    May 6, 2014 at 14:26
  • Why is it important to you to hear the system start up sound in both speakers? .....I asked you to look in your Console boot log and publish the first 50 lines here.
    – Ruskes
    May 6, 2014 at 22:42

1 Answer 1


This seems to be a problem for a particular number of MacBook Pro models starting in 2010. According to this article in the Apple support site, the following models have a sub-woofer speaker in addition to the left and right speakers to enhance mid-range sounds.

  • MacBook Pro (15-inch, Early 2011)
  • MacBook Pro (15-inch, Mid 2010)
  • MacBook Pro (15-inch, Late 2011)
  • MacBook Pro (15-inch, Mid 2012).

Looking at this article in the Apple discussion boards and this article here on Ask Different, users of these models are experiencing the same issue. If I had to guess, every model with this sub-woofer acts the same way and only a few users have noticed it.

There may not be a way to correct this. I hope this information helps.


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