[LAD] A little quiz about audio measurements...

[Ralf Mardorf]

Veronica Merryfield wrote:
> On 2010-05-28, at 11:39 AM, Ralf Mardorf wrote:
>
>   
>> Niels Mayer wrote:
>>     
>>> If the "close" has to do with induced or actual 50hz hum, perhaps
>>> frequency-doubled via rectification:
>>>       
>> It's the residual ripple for the DC that comes with 100 Hz. 50 Hz hum is 'send' by the transformer and could be heard as additive analog audio signal, because of the 'electric smog'.
>>     
>
> The times I have measured the power line frequency to check it's effect or otherwise, I have not measured it as exactly 50.0hz (when I lived in the UK). 
>
> Vrnc

I do agree, unfortunately I can't watch my meter right now, anyway, the 
graphic might have distances of around 100 Hz.