Re: Advice on transformer hum
Reply #28 –
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Very simple question: have you actually taken your devices to a friend's house some distance away to check whether the hum is still present? If it is, the devices are probably at fault. If it isn't, your mains supply is the source of the problem. Until you've established this one way or another, you can't begin to find a solution.
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Yes, taking the units to a distant location should be one of the first tests for power line problems.
But while DC offset problems are mostly rather local, high line voltage (with respect to your unit's transformer design voltage) is becoming universal. Last week our weather was very cold but our line voltage was 125V/125V. Now it's above freezing and the line voltage remains at 125V.