I couldn’t justify the price of a 156 as I need something like 23 sockets for transformers, although the noisier ones are probably nearer 15
Having graphed out the mains voltage can you give us feedback on transformer hum at these times relative to graph readings?
Once again balanced supply, say goodbye to naim hum, plus no sound quality loss, just lovely blackness quite
To be honest in my home there is no correlation with transformer hum. Only the 500 PS hums. Before with a 252/300 (all DX) the 555DX hummed. It went completely quiet! I guess the hum is more to do with the spatial coupling between the coils or the interaction as they draw from the mains.
I don’t hear the minor hum when I’m listening nor do I try to hear it. It don’t think it impacts on the music.
What the meter tells me is that the voltage varies throughout the day. It’s high when grid demand is low and lower when’s demand is high. It is within the grid limits.
Phil
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I can confirm that when I reported an average Voltage of 255V to the Electricity Board, they came, and during investigation, dropped it for a day to 240V. That pretty much stopped my humming. Unfortunately the final fix they put in place leaves me with a value in the late 240’s, and humming is back but not to original levels. But of course this is only one possible reason for humming.
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Excuse my ignorance but is a balanced supply and what do you need to achieve this?
A balanced supply is where you have 115volts going down both the live, and natural.
This works just like a balanced xlr cable in that they each cancel out each other as far as any interface, noise, etc.
It’s not that expensive to do, around £500, but it depends on what load you are running.
It’s not a new thing, hospitals, recording studios, measuring equipment, etc. They all use tend to use balanced supply.
It’s a proven way, its a simple way, and it far cheaper than fancy mains blocks.
I have a separate mains supply to my hifi, from a separate consumer unit, the balanced transformer goes between the hifi consumer unit and the main tails into the house aftet meter.
Cheers dunc
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Interesting solution, thanks.
If you’re interested, look at Airlink. They produce a good range of balanced and other power supplies, including some suitable for HiFi, and they are very helpful.
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Bear in mind that this is a transformer, and therefore can also hum, so best sighted back at your dedicated HiFi Consumer unit if possible
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Mine is a very large airlink hifi model, and pleased to say it doesn’t hum
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I certainly don’t doubt you, and it may be because your supply isn’t that bad. Someone on this Forum did say that theirs did Hum. I believe Airlink used to have a good returns policy if you aren’t pleased with the results, so certainly worth considering. I did call them when I was looking into this, and they used to supply model that will reduce the voltage which might have been useful for my overvoltage problem.
Which model are you using please. I have a separate consumer unit, earth spike and three separate ring mains and still get a hum in my power amp 
You can connect to 3 different input voltage supply coils on mine.
This helps the transformer, as said mine doesn’t hum, but even if it did it wouldn’t really matter as it’s not in my hifi room, or in any room.
My mains, consumer unit’s are under my stairs, in a cupboard.
For more info take a look at my thread i started a few months ago.
Airlink distrbute their products worldwide. They sell a selection of products with UK, Euro, US and other sockets.
I think hum frequently comes from “bad” electricity.
Try to test your ground voltage, polarity also your cabling quality.
hopefully its help
Yup. I got my electricity replaced ( that central box for which I don’t know the English name ) and somehow it’s all much more silent.
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