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US mains frequency to be changed...what will be affected?

post #1 of 5
Thread Starter 

http://news.yahoo.com/s/ap/20110625/ap_on_hi_te/us_sci_power_clocks

 

Apparently the standards on mains frequency are going to be loosened in the US. No articles I can find give actual numbers or specs, but apparently it's something like instead of steady 60,00Hz it will be 60Hz +/- something. Again, I can't find any actual numbers in any articles except dumbed-down ones like 20 seconds per year (as if that told you anything useful).

 

What audio equipment could be affected by this? Most modern/commodity stuff has switchmode PSUs. Amplifiers with regular power supplies won't care about mains frequency, although there could be some extra harmonic content in the mains (again, it sure would be nice to have actual numbers).

 

Does anyone here know anything about Technics turntables? I have an SL1600 that has a strobe for you to adjust the speed with, but I don't know if the strobe itself is sync'd off the mains or of it has its own crystal source. And I don't know if this turntable speed itself will change if the mains frequency changes. I used to have a cheap Marantz turntable that had a synchronous motor. A turntable like that would definitely be affected by mains frequency. Most of the high-end-belt-drive turntables use servo or stepper motors so their speed won't be affected. But what about Technics? Can you think of any other audio gear that depends on a steady mains frequency?

post #2 of 5

Wow, interesting question... I wonder if one of the EE fellas on here could shed a little light for we laypeople!! :)

post #3 of 5

should make no difference

post #4 of 5
Could be a slight problem for some turntables with AC motors that depend on the frequency to determine speed. There are work-arounds, though. Mine has an AC motor, but it also has an external box that precisely regulates its speed. Should be OK. I'm not sure what your Technics deck uses, but to take a guess, it uses a quartz crystal to regulate speed - much like a quartz watch. Should be fine. If I'm wrong, I hope someone corrects me.

Most audio gear won't be affected at all. After the AC comes into the box, it goes into the power supply to be converted to DC. Among other things, the power supply is designed to entirely eliminate the AC frequency. A mild fluctuation won't matter, you'll still get clean DC on the other side of the power supply. That's the part that matters.

Also, it doesn't sound like the frequency is changing. They're just loosening the standard a bit. The power companies' beancounters probably thought they were spending too much money on regulating the frequency, so they had some lobbyists hand out cash to get it changed.
post #5 of 5

It'll make no difference to any audio equipment, and very little difference to clocks because on average you'll spend just as much time ever so slightly below 60Hz as you do ever so slightly above 60Hz. 

 

In most power systems you won't see a solid 60Hz all of the time anyways, frequency will change depending on system loading conditions, and transients (faults, industrial processes, etc.). At least one generator on a system is operating in "isochronous" mode, meaning that it sets the speed (frequency) of the power system. The other generators are synchronized to it and will vary speed to keep system frequency stable at 60Hz.

 

 

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