Hey Sulthon. I am also experiencing a crackling/popping noise. I thought like you that the speaker was the culprit, and upon changing both left and right speakers, the crackling persits!...rats.
For the nature of my case, the crackling starts/persists when I am in a warmer room or in my bed using the laptop, and it stops when the computer is in a physically cold space like in my basement or on a cool counter surface. So that has lead me to the deduction that the problem is temperature-related.
Temperature could increase or decrease with the physical environment its in, but also when the computer is demanding a lot of processing power,
I've done some research and I think I've narrowed it down to the battery, thermal paste connections, and fan cleaning.
There is a phenomenon with these batteries where they overheat, swell up and cause a gas exchange. See here.
Overheating is a definite concern for computers in general and has been for a long time, this is no exception. Ensuring proper thermal paste connections is crucial for heat dissipation. I know mine will need to be reapplied.
A lot of forums were suggesting that the HDD could be a culprit due to the energy demands they require but since we have an SSD in this model, I do not think this crackling sound is coming from there.
I will change the battery, re-apply thermal paste and clean the fan, and hopefully the sound will stop!
crwdns2934105:0crwdne2934105:0
crwdns2934113:0crwdne2934113:0
crwdns2915270:0crwdne2915270:0
crwdns2889612:0crwdne2889612:0
0
2 
1 
crwdns2944067:02crwdne2944067:0
I also have this issue, your solutions seems to work, I believe your going to be fine not bringing it to the Apple Store.
crwdns2934271:0crwdnd2934271:0 Julian Sanchez crwdne2934271:0
I am same problem with Macbook 2018
waiting for proper solution
Thanks
crwdns2934271:0crwdnd2934271:0 smmvillage crwdne2934271:0