I have a 2015 Honda Accord with standard audio, just had an installer upgrade front speakers with Focus speakers. When car is started up after a few seconds the speakers will have a low frequency hum that lasts for a few seconds and cycles 4 times, opening any door will interrupt this but will resume on closing the door once the cycles are over it is fine. This happens with audio on or off, installer removed both speakers to isolate ground issues, changed to lower cost versions, still happens but at a lower volume, he thinks maybe problem was there with stock speakers but of such poor quality i did not notice. Any ideas? Thanks Greg
