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HiFi Systems AC or DC? - some questions

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klugkopf

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HiFi Systems AC or DC?

Hi

I need to know if HiFi Audio systems work internally with AC power or with DC because I need to know if they're frequency dependent or not (sensitive to change in 50/60 Hz in different parts of the world). The model I have in mind is the Sony MHC-GX20 sold in the U.S. (http://www.sonystyle.com/home/item.jsp?hierc=9686x8643x8719&catid=8719&itemid=30643&type=o) which doesn't have a 110/220 switch. Can I use it in Europe with a transformer without frequency change from 60 to 50 Hz being a problem?

Any help is appreciated
 

ted

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I do not know that particular system, but any normal construction has either mains-frequency transformer based or "primary switcher" type mains-to-internal-DC power supply.

Assuming an old-fashioned mains frequency transformer: In most cases you can use an transformer to convert 220-230V down to 110-120V range with an 2:1 transformer and assume that 50 Hz is OK for a device designed for 60 Hz. A transformer designed for 60Hz will work slightly warmer when given 50Hz due to heavier magnetization, but I believe all sensibly dimensioned constructions can take that. In all cases when I have personally adapted an American device to European voltage, I have not observed any serious overheating.

In case of primary switcher, the frequency should mean even less. However, the power factor figures can be anything from near-one (for new and good constructions) to ugly (old directly rectifying non-power-factor-corrected ones). The latter may demand a biggish transformer for good function.

But one warning: Do NOT use those small, lightweight, "travellers transformers" for the purpose. Get rather a big, heavy, and preferably bit overdimensioned real iron-and-copper transformer. (Remember, transformer size is function of VoltAmps, not Watts, and power factor can make VA figure much higher than wattage for those built in AC/DC power supplies!)

Also, for electrical safety, it is better to use an isolating type transformer (not non-isolated one), even if they usually cost more, and are somewhat bulkier.

Good luck,
Ted
 

shanren

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just see the voltage of the systems,do not mind 50hz or 60hz.a transformer can convert Europe voltage to US voltage can do the job.but the transformer will big enough,should about 1.2-1.5 times than all the system,if 2 times will be good.DC is dangerous,because inside the system mostly is a transformer.
 

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