Don't know without knowing exactly where you connected the probes to, that is, what were you measuring? Regardless it is no 3 V DC, the meter shows 0.031 V, not too much to worry about even if your were measuring the voltage at the amplifier's output for example, though lower would be better.
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Marantz AV10 AV Processor Review
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Don't know without knowing exactly where you connected the probes to, that is, what were you measuring? Regardless it is no 3 V DC, the meter shows 0.031 V, not too much to worry about even if your were measuring the voltage at the amplifier's output for example, though lower would be better.
I was measuring one of my outlets to see if I can measure the DC. I think I have a DC Offset at home it would be great to see how much DC is leaking in.
Measure at the power amp/speaker binding post outputs should tell you that, and that's what matters anyway.
So how should I measure I'm having problems with my REL subwoofer it is making noise when I only have the power cable connected nothing else my dealer gave me the t7x and the t9x and I own the t5i and all three had the same problem I am suspecting that it is a DC Offset because all those Models have class AB amplifiers with toroidal Transformers. So if I can measure the DC offset maybe I can buy a DC blocker that can filter out how much DC is coming in.
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Not really, there was a bit of a language barrier trying to understand exactly what it was you were trying/wanted to do. your post was just a bit confusing.
Glad you got it all straight.
How I want to measure how much DC is coming in
But I have not solve this issue. How do you measure how much DC is coming in? I asked two of my local electrical companies and they don't know.
Then maybe you missed my post#1761 in which I responded to your question. You measured 31 mV dc, but you just said "on my mains" so I guess most would assume you measured it at the outlet, or really somewhere inside the incoming panel ? 31 mV dc is not perfect but is not an issue and you local electric power utility company is no going to worry about it at all. What exactly is the issue you are experiencing?
I had an electrician over and that does not measure DC that is coming in or a DC offset. He told me that there is one company that can measure this and they have some specialist equipment so I am waiting for them to come, but thanks anyway.
Maybe, as I don’t know how you did your measurement, so may be you did it right, or not. Not all electricians know much about d.c offset. I worked with, and have had many electricians worked under my supervision over the years, some knows a lot, but some…. So, be careful with what the offer, and how much they charge.
Again, what really is the issue, transformer hum, or something else? If we know what we are dealing with, some of us may be able to suggest something useful.
It is transformer hum.
All transformer hum, but I am sure you know that too. It is loud enough, audible within a couple of feet then in my opinion/experience I would consider that excessive, otherwise, if you only hear it with hear touching the chassis, or barely audible from less than a foot or two, I would just focus on enjoying the music.
It is highly unlikely for the cause to be the dc from the utility incoming power supply. If it is, you would hear that kind of hum from other similar amplifiers.
There is an interesting thread on ASR that may be worth reading, in you are interested in the potential causes other than the dc offset thing.
Mains related hum and noise in power amplifiers
Mains related hum and noise in power amplifiers We have had some discussion in another thread https://www.audiosciencereview.com/forum/index.php?threads/class-a-vs-ab-do-they-really-sound-different.18415/post-910720 about the reason of higher residual mains related components hum in the...
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In my home, the loudest hum I heard was from two of my relatively expensive amplifiers, the Bryston 4B SST and Parasound Halo A21, both have reasonably large toroidal transformers, and toroidal transformers are more prone to hum. All of the AVRs and smaller power amps were silent unless I stick my ears on the chassis. Same house, same incoming power.
My problem has been REL subwoofers I just cannot get them to be quiet and my suspicions are that the transformer is making noise and then sending it to the subwoofer because the Rel subwoofers are very detailed subwoofers so I think that they will react at anything that comes their way and they use class AB amplification with toroidal transformersAll transformer hum, but I am sure you know that too. It is loud enough, audible within a couple of feet then in my opinion/experience I would consider that excessive, otherwise, if you only hear it with hear touching the chassis, or barely audible from less than a foot or two, I would just focus on enjoying the music.
It is highly unlikely for the cause to be the dc from the utility incoming power supply. If it is, you would hear that kind of hum from other similar amplifiers.
There is an interesting thread on ASR that may be worth reading, in you are interested in the potential causes other than the dc offset thing.
Mains related hum and noise in power amplifiers
Mains related hum and noise in power amplifiers We have had some discussion in another thread https://www.audiosciencereview.com/forum/index.php?threads/class-a-vs-ab-do-they-really-sound-different.18415/post-910720 about the reason of higher residual mains related components hum in the...
In my home, the loudest hum I heard was from two of my relatively expensive amplifiers, the Bryston 4B SST and Parasound Halo A21, both have reasonably large toroidal transformers, and toroidal transformers are more prone to hum. All of the AVRs and smaller power amps were silent unless I stick my ears on the chassis. Same house, same incoming power.
Newman
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That is not what is usually meant by transformer hum.
When you see online advice that DC on the AC mains can induce hum in toroidal transformers, it is mechanical hum.
DC on the AC mains does not induce electrical hum (50/60 Hz AC electrical signal) that somehow escapes the capacitor bank immediately downstream of the transformer.
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I missed this post, but if @Newman understood your post correctly (I don't, not quite), then it would explain why your measurements seemed to show your don't have a dc offset issue from your ac incoming but likely your subwoofer amp has some sort of ground loop related noise.
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