What is the hum / noise on my microphone & headphones?

Morning everyone - I am using the EB70 to run my laptop off AC, but I am finding on work Teams calls that there is an electrical hum / buzz present on my microphone which others can hear. The same hum is present in my headphones and gets louder if I hold the cable. It sounds like a “mains hum” but I haven’t recorded it to check. Does anyone have any experience of this and any suggestions to resolve? Would running my laptop off DC (45-65w PD) resolve it, even if the two attached monitors are running on AC, perhaps the hum would be introduced through the monitors anyway?


You are correct - anything in the audio chain can insert noise - as an example, my balanced audio system had noise/hum - did some research and it was suggested to disconnect my cable TV coming into the house - no connection to my system whatsoever and the hum was completely eliminated. Could also be coming from EB70 - could try an isolator in front of laptop as well.

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Thanks Brandon for your helpful comments.

A little more info on this for anyone searching - the buzz is coming from the 240v inverter. If I power devices off the 12v DC only, there is no buzz. Switch on the inverter and it begins.

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I had this issue as well and seems like nothing can be done here, and the problem is not in the unit, but in the physics itself, meaning if the unit works correctly then this sound MUST be present.
I am not an electrician, but I will try to explain.
See, the battery does not have the nulling to get rid of some chaotic charge roaming around, and this is exactly what you are hearing. If your laptop has a metal case, then if you touch it with your hand you may feel a little of electroshocking feel (that you may barely feel) and at the same time this buzzy sound will be reduced, as your body now works as a nulling in the chain. The same effect can be achieved by touching with your finger a gap on between inserted USB port (specifically touching a metal part of a male input).

So this is normal and there is not much you can do about it. Just power your laptop from the grid while you have electricity if this sound really annoys you, but to be honest it is not too loud at all and barely noticeable while you are listening to something.

I listen to shortwave radio with a Software Defined Radio installed on the PC. This software allows you to “see” right across the radio spectrum and what I see is interference “hum/noise”. Turning off the AC200Max eliminated the interfereance. The Bluetti isnt connected to the mains in any way and not powering any AC items but while it takes a charge from the solar panels. Zap!!! So at least at my home it’s the charge controller.

I had an odd case of ham radio interference from my Asus wifi router. It was only when I tried to use a certain ethernet slot on it. No problem with any other slots, but only that particular one. I had stated using an ethernet cable on a gadget because it kept losing my wifi password. Problem solved when I plugged the cable into another slot on the Asus. Weird.