A few days ago I bought a TCL 55S425 Roku tv, upgrading from my TCL 49S405 Roku tv. Ever since setting up my new 55 inch, the speaker it is connected to randomly will emit a loud popping/crack noise. It happens for a brief second, and it will repeat probably every 20-40 minutes. I have my 55inch connected to a Woburn speaker using a aux cord using the headphone output. My 49inch TCL was setup the exact same way to my speaker, and never once did I experience the pop/cracking noise that I do now. I made sure that my 55inch is updated fully, so that doesn't seem to be the issue. I also turned the audio to stereo instead of auto-detect. This is very frustating, my older tv had no issues with the setup.
I am having a similar issue on my 55S425 which I purchased yesterday. Whenever coming out of a fast forward situation while watching, DVR, Netflix, etc. There is a brief "electric" popping sound. I am using the internal speakers and I have done a full factory reset.