amandeep242 Said:
"I bought this mac in September 2019 and it was working fine. Suddenly 4 months back, the crackling sounds started from the left speaker. The noise is not there when external audio device is used. Any comments on this?"
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Get this Serviced, ASAP!:
If this was purchased from Apple back in September, then I insist you get this serviced, especially if no AppleCare protection was purchased with this.
It may be a hardware issue. You have a one-year, out-of-the-box, limited-warranty with this. So, contact Apple Support, seeing if this can be worked on.
Without AppleCare protection on this, the out-of-the-box warranty is due to expire in only three or so months from now, as of this reply.
Contact Apple Support: