I've had a look through the forum and a few people seem to have experienced similar problems to this, not sure if its exactly the same but no real answer as to why so i thought i would post a vid to properly explain the issue.
One of my speakers seems to go through little intermittent popping fits every now and again for no reason - the speaker will seem to be in pefect working order for an hour or so before doing this, then it will be fine again for 30-60mins again. I also experience some hissing and interference occasionally, often when I just turn it on... then it surpasses. The other speaker is fine.
The popping persists even when I take out the XLR so that leaves me to believe something is amiss with the power hardware in the speaker but I have no technical knowledge of this. As the other speaker is plugged into the same power brick and has no issue I think its the speaker itself, also i have tried different power cables to no success.
If anyone could shed any light on what this might be, if its fixable and if they know any places in and around London that might be able to do this I would appreciate it!