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Understanding Audio Measurements

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#81
I hope this is right thread to ask:
many bad measurements are caused by poor power supply or power supply related issues.

Does it matter if measured unit is 110V or 230V (or 110/230V switchable unit, 50/60Hz hum etc).

Thanks again
 

RayDunzl

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#82
Does it matter if measured unit is 110V or 230V (or 110/230V switchable unit, 50/60Hz hum etc).
50Hz hum at the output (at the same level) might be slightly less audible...

230V may radiate EMF more strongly than 120V affecting whatever gets affected (guessing a bit here), or even more weakly, as the current flow would be reduced vs 120V (all else being equal).

Does it matter, one over the other? Probably not.
 
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RayDunzl

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#83
Based on the above "answer", I have an EE question;

I have a wire energized with a sine wave voltage, and some current flow. Mabe later it is only energized, but no flow.

Is there one, or two fields around it... I'm thinking what I might call "electrostatic" induced by the voltage and the other "magnetic" induced by the current, or are they the same thing, or what?
 
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dc655321

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#84
@RayDunzl
There are two orthogonal fields: a concentric magnetic field and a radial electric field.
Been a while since I thought about EM theory, so could very well be thinking wrong about this.

EDIT: no current (flow), no mag field.
 
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DonH56

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#85
^^^ You could be right! See Maxwell's equations (didn't everyone have to memorize them? And the periodic table...)

With voltage there is a electric field, which may be static or not. ESLs depend upon that voltage field. If there is current flow then there is a magnetic field at right angles to the current flow (see right-hand rule). The magnitudes depend upon the voltage, current flow, and distance from the conductor (wire). All basic EM problems seen in any undergrad course, i.e. something I knew something about in 1984 or so and have mercifully forgotten by now.
 
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