I'm not sure what you mean by "grid hum," but it sounds like you have DC on the line. That could come from the utility itself or from within your house. Is this hum you can hear coming only from a component transformer, or do you also hear it through the speakers?
power grid issues?
Hi Agoners. By chance, are there any bright EE around who may have an answer to this? I get "grid hum" on my Balanced Audio Technology tube amp. It is irregular, happens for different intervals and different lengths of time. I have check my house system by shutting evert appliance of during these "hum intervals" and I do know it is not my house systems that are creating this noise, or fluctuation. I had PG&E check their system. They used a neutral detector and said that their neutral to the source is good. The power is stable. This morning the hum, which is audible in the transformer, was a wave. on off on off on off, for a good hour. then it stopped. Yesterday it was just a straight hum for a period of time. no fluctuations at all. What is going on?
Thanks for any input!
Greg
Thanks for any input!
Greg
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the hum i am referring to is my transformer on my tube amp. PG&E has assigned an EMF specialist to help determine where the noise is generated. I do not believe at this time that it is generated from my house due to its irregular intervals, i.e., time of day, inability to duplicate it when it is not there, everything turned off in my house. Yesterday it was a constant hum for at least and hour this morning it was an oscillating hum for about an hour. I am on the same line as my neighbor. We are the only two houses connected to the transformer across the street. They have solar panels that run off of AC. I took my amp and plugged it into different circuits in my house and got the same hum. Maybe I should go to my neighbors house and plug it in to find out if it would hum over there. |
It sounds like the age-old issue of having DC on the line. This will cause mechanical vibration in the transformer. I would not just turn off appliances, I'd turn off all the breakers to see if it's something in your home. Usual suspects are digital supplies, as well as LED or high efficiency light bulb supplies. Hair dryers, and dimmer switches. The permanent fix for this is to use a balanced power conditioner. Furman, Equitech, Torus, etc. will eliminate this completely. There are also smarter, less expensive devices like this from Emotiva, which I have not tried: https://emotiva.com/products/cmx-2 Best, E |
I found this article, and it seems to be pretty comprehensive: https://www.pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html |
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